Removal and referral of organs and tissues for forensic chemical examination. The procedure for conducting a forensic chemical examination. The main stages of chemical analysis.
The science of measurements, methods and means of ensuring their unity and methods of achieving the required accuracy is called metrology. Quantitative chemical analysis, the purpose of which is to determine the content of substances in different objects, can be considered as a measurement procedure characterized by a number of specific features.
Quantitative chemical analysis is primarily a multi-step process involving a number of steps and steps. When performing chemical analysis using any method, the following main steps can be distinguished:
Statement of the analytical problem;
Selection of analysis method;
Perform analysis;
Assessment of analysis quality;
Making decisions based on the results of the analysis.
When setting up an analytical problem, it is necessary to characterize the object of analysis, indicate the chemical formula of the component being determined, the possible range of its contents, the required accuracy and duration of the analysis.
The choice of analysis method is determined by the analytical task and the technical capabilities of the analytical laboratory.
The stage directly related to chemical analysis is the most labor-intensive and includes a number of stages presented in Fig. 5.2.
Method of analysis includes a detailed description of the sequence and conditions for carrying out all stages of the analysis. Accurate adherence to the analysis methodology allows you to perform the analysis with minimal errors at each stage and obtain the correct analysis result.
The first stage of chemical analysis is selection average (representative) sample. This is a small part of the analyzed object, the average composition and properties of which must be identical in all respects to the average composition and properties of the analyzed object. The content of the component being determined in the analyzed sample must reflect the average content of this component in the entire object under study, i.e., the analyzed sample must be representative. The error in sampling often determines the overall error in the chemical analysis. Without assessing the error at this stage, it is impossible to talk about the correctness of the determination of the component in the analyzed object.
Preparing a sample for analysis involves a number of complex operations, such as sample drying, decomposition (opening) samples, eliminating the influence of interfering components. Depending on the purpose of the analysis, the nature of the object and the chosen method, various modifications and combinations of these operations can be used. In the correct conduct of chemical analysis, the role of sample preparation is so great that the analytical chemist must each time evaluate the need to include sample preparation operations in the analysis procedure and their impact on the overall analysis error.
After sampling and preparation of the sample, the stages of chemical analysis begin, at which the amount of the component is determined. For this purpose, they measure analytical signal. In most methods it is the average of measurements of a physical quantity at the final stage of analysis, functionally related to the content of the component being determined. This can be current strength, EMF of the system, optical density, radiation intensity, etc. In some analysis methods, direct determination of content is possible. For example, in the gravimetric method, the mass of the component being determined is sometimes directly measured.
When determining the amount of a component, the magnitude of the analytical signal is measured. The component content is then calculated using the functional relationship analytical signal from content: y= f(c), which is established by calculation or experience and can be presented in the form of a formula, table or graph. The content can be expressed as the absolute amount of the analyte in moles, in units of mass, or in terms of corresponding concentrations.
When measuring an analytical signal, the presence of a useful analytical signal, which is a function of the content of the component being determined, is taken into account, and analytical background signal, caused by impurities of the component being determined and interfering components in solutions, solvents and the sample matrix, as well as "noises" in measuring instruments, amplifiers and other equipment. These noises are not related to the component being determined, but are superimposed on its own analytical signal. The analyst’s task is to minimize the magnitude of the analytical background signal and, most importantly, to minimize its fluctuations.
Typically, the analytical background signal is taken into account in control (blank) experiment, when a sample that does not contain the component being determined is passed through all stages of chemical analysis. An analytical signal equal to the difference between the measured signal and the analytical background signal will be useful.
Based on the existing relationship between the analytical signal and the content, the concentration of the component being determined is determined. Usually they use graduated schedule methods, standards or additives Other methods for determining component content described in the literature are usually modifications of these three methods.
Most common Calibration chart method: in coordinates (analytical signal - component content), a graph is constructed using comparison samples with different and precisely known levels of component content (concentration WITH). Then, having measured the value of the analytical signal in the sample, the content of the component being determined is found according to the calibration graph (Fig. 5.3).
IN standards method measure the analytical signal in a comparison sample (standard sample) with a known component content and in the analyzed sample: U st = sS st i y x = sС X, where s is the proportionality coefficient.
If the value of s determined under identical conditions is known in advance, then the calculation can be carried out using the formula C x = Y x / S. Usually the ratio is used U st /U X = WITH st/C X, from where
Sometimes they work with two standard samples, in which the content of the component differs from the expected content in the analyzed sample, in one case to a lesser extent, in the other - to a greater extent. This version of the standards method is called using the limiting solution method. The content of the component being determined is calculated using the formula
If, when determining small amounts of a component, it is necessary to take into account the influence of the sample matrix on the value of the analytical signal, then often use additive methods - calculated or graphical.
When determining content calculation method take two aliquots of the analyzed sample solution. An additive of a known content is added to one of them. In both samples, the analytical signal is measured - y x and y x+ext -
The unknown concentration of the component being determined is calculated using the formula
where V add and C add are the volume and concentration of the added solution of the component being determined; V- an aliquot of the analyzed sample.
When determining the content of a component graphical method take P aliquots of the analyzed sample: 1, 2, 3, ..., P. In the 2nd, ..., p-y aliquots introduce known, increasing amounts of the component being determined. In all aliquots, the analytical signal is measured and a graph is plotted in the coordinates analytical signal - content of the analyte component, taking the content of the analyte component in the aliquot without additive (aliquot 1) as a conditional zero. Extrapolation of the resulting straight line to the intersection with the abscissa axis gives a segment to the left of the conditional coordinate zero, the value of which on the selected scale and units of measurement corresponds to C x of the determined component (Fig. 5.4).
The standard method and the addition method are applicable for the linear calibration function. The calibration plot method allows the use of both linear and nonlinear analytical signal-content functions. In the latter case, a larger number of experimental data is required, and the result of determining the component content is, as a rule, less accurate.
SELECTED LECTURES ON TOXICOLOGICAL CHEMISTRY
The textbook was prepared for publication at the Department of Toxicological Chemistry of the State Educational Institution of Higher Professional Education of the Perm State Faculty of Healthcare of the Russian Federation by associate professors T.L. Malkova, N.V. Koksharova, E.V. Meteleva, E.N. Kozminykh, senior teachers L.N. Karpova, O.N. Dvorskaya
Under the general editorship of the head. Department of Toxicological Chemistry, Associate Professor T.L. Malkova
Reviewers:
and about. head Department of Toxicological Chemistry, Pyatigorsk Pharmaceutical Academy, Associate Professor T.Kh. Vergeichik;
head Department of Ecology of the Perm State Agricultural Academy, Associate Professor E.V. Pimenova;
Associate Professor of the Department of Analytical Chemistry of the Perm State Faculty of Physics N.V. Kolotova
Third edition, revised and expanded.
Recommended by the Educational and Methodological Association for Medical and Pharmaceutical Education of Russian Universities as a teaching aid for students studying in specialty 040500 - “Pharmacy” (UMO-851 12/24/04)
| Introduction to Toxicological Chemistry | |
| Organizational structure of forensic medical and forensic chemical examination in the Russian Federation | |
| Legal and methodological basis of SME | |
| Rules for the forensic chemical examination of material evidence | |
| I. General characteristics of toxic effects | |
| General characteristics and classification of substances that cause poisoning | |
| Toxicokinetics of foreign compounds | |
| A group of substances isolated by distillation (“Volatile poisons”) | |
| Monohydric alcohols. Ethyl alcohol in chemical and toxicological terms | |
| Chemical properties of alcohols. Methods of analysis in forensic chemical examination of poisoning and examination of alcohol intoxication | |
| Quantitative determination of alcohols | |
| A group of substances isolated from biological material by extraction and sorption (“Medicinal poisons”) | |
| Theoretical basis of isolation methods | |
| General and specific isolation methods | |
| Purification of isolated substances from accompanying components of biomaterial | |
| Analytical screening of medicinal substances of toxicological significance | |
| Derivatives of barbituric acid in chemical and toxicological terms | |
| Alkaloids in chemical and toxicological terms | |
| Express analysis of intoxications A group of substances isolated by extraction with non-polar solvents. Pesticides | |
| A group of substances isolated by mineralization (“Metal poisons”) | |
| Mineralization methods | |
| Fractional method of analysis | |
| A group of toxicologically important substances isolated by extraction with water (mineral acids, alkalis and their salts) | |
| A group of toxicologically important substances that require special isolation methods (fluorine compounds) | |
| A group of substances that do not require special isolation methods. Harmful vapors and gases. Carbon monoxide | |
| Literature |
The lecture material includes the main, most important sections of the toxicological chemistry course: issues of sample preparation and isolation with theoretical justification and practical application of methods, analytical toxicology, which considers issues of purification, concentration of toxic compounds, as well as the correct use of the capabilities of various methods of analysis, their rational combination. Much attention is paid to modern methods of analysis: chromatographic, spectrophotometric, immunochemical and others.
Information about the physicochemical characteristics of toxic substances allows one to correctly navigate the degree of their toxicity and the diverse chemical transformations that occur with them in the body. The issues of metabolism and elimination of toxic substances are covered.
The lecture material pays attention to the modern organizational structure of forensic and forensic chemical examination, as well as the legal and methodological foundations of forensic chemical examination.
“Selected lectures on toxicological chemistry” were compiled in accordance with the current program (2003), taking into account the requirements of orders of the Ministry of Health of the Russian Federation, and also due to the lack of a modern textbook on the course of toxicological chemistry. The educational and methodological manual will undoubtedly be useful for students of pharmaceutical universities and practical workers.
Introduction to Toxicological Chemistry
· Subject and tasks. Relationship with other disciplines. Peculiarities.
· Basic sections of toxicological chemistry.
· Main directions of chemical-toxicological analysis.
· Stages of formation and development of toxicological chemistry.
The name of the subject “Toxicological chemistry” itself shows that this is a science related, on the one hand, to toxicology, and on the other, to chemistry. Toxicology is a medical science. Its name comes from two Greek words: toxikon - poison and logos - teaching. Toxicology, therefore, is the science of poisons and their effects on the body (human, animal, plant).
Toxicological chemistry arose from the needs of toxicology, which is reflected in both the name and content of the subject. During the period of its formation and development, toxicological chemistry was associated mainly with forensic toxicology and was called forensic chemistry, and in 1965 it was renamed toxicological chemistry). In other countries, with the same content, this subject is called forensic chemical toxicology, analytical toxicological chemistry, chemical toxicology, analytical toxicology.
The program for pharmaceutical universities, approved by the Ministry of Health of the Russian Federation in 1996, provides the following: definition of the discipline being studied :
Toxicological chemistry is the science of chemical transformations of toxic substances and their metabolites in the body, methods of their isolation from objects of biological origin, detection and quantification.
In the textbook “Toxicological Chemistry” by M.D. Shvaikova, which is still in force today, published in 1975,
Toxicological chemistry is defined as the science of chemical methods for isolating, detecting and determining toxic and potent substances, as well as the products of their transformation in the tissues, organs and fluids of the body (animal, plant) and in the human environment and objects (water, air, soil, residues food products, medicines, etc.)
A characteristic feature of modern toxicological chemistry is a significant expansion of the arsenal of chemical compounds potentially dangerous to humans and animals. The potential for poisoning lies in the widespread use of chemicals in medicine, industry and everyday life, in the availability of various chemicals to wide sections of the population, who are not always sufficiently familiar with the toxic properties of these substances used as medicines, pesticides, household chemicals, as well as in attempts self-medication, etc. A constant increase in the number of poisonings, especially from drugs, has been observed in recent decades in almost all developed countries of the world. Of no less importance is the pollution of the human environment (water, food, air in modern cities, etc.) with industrial waste, the accumulation in these objects of a large number of substances, which under certain conditions can cause poisoning.
Main tasks modern toxicological chemistry as a science therefore continues to remain:
¨ development of new and improvement of existing methods for the isolation (isolation), detection and quantitative determination of toxic substances in fluids, organs and tissues of the body and in the external environment, as well as methods for the isolation, detection and determination of the products of their transformation (metabolites) in a living organism and in a corpse.
The solution to these problems is aimed at diagnosing poisoning, providing quick assistance to the poisoned person, and preventing all kinds of poisoning with toxic substances.
Toxicological chemistry is special pharmaceutical discipline and is interconnected with other disciplines:
· medical (pharmacology, forensic and clinical toxicology),
· biological (biochemistry, biology, pharmacognosy),
· chemical (pharmaceutical, analytical, organic and other chemistry).
It should be noted that toxicological chemistry as a special pharmaceutical discipline is taught only in pharmaceutical universities in the country.
Mastering the basics of toxicological chemistry is necessary for a pharmacist for subsequent specialization in the field of forensic chemical examination, clinical toxicology and pharmacy, forensic science, ecology and sanitary chemistry.
Toxicological, formerly forensic chemistry, should be considered a relatively young science. The year of its legalization is considered to be 1714, when Peter I issued a Military Decree on the mandatory establishment of the cause of death of persons who died a violent death (a forensic autopsy of such corpses was mandatory).
Forensic chemistry was created through the efforts of pharmacists. Through the works of these same specialists it has developed and is currently developing.
The following scientists stood out for their activities in the field of forensic chemistry:
A.A.Iovsky(Moscow University) in 1834, for the first time in Russia, published in Russian a manual on forensic chemistry, which he called “Guide to the recognition of poisons, antidotes and the most important determination of the former both in the body and outside it by means of chemical means called reagents.”
A.P.Nelyubin Head of the Department of Pharmacy at the Medical-Surgical Academy of St. Petersburg. In 1824, he published the first “Rules for the guidance of a forensic doctor in the study of poisoning,” where for the first time in the world he theoretically substantiated the need to destroy an object (organic substances) during forensic chemical and other studies on “metal poisons,” and proposed his own method of destruction, substantiated a method for detecting arsenic compounds after its reduction to arsenous hydrogen.
A.P.Dianin Professor of the Medical-Surgical Academy worked there for more than 30 years and during this time performed about 5 thousand forensic chemical analyzes. In 1903, Dianin received the title of academician of the Military Medical Academy, and in 1904 - the title of chief forensic chemical expert.
G. Dragendorff, a professor at Dorpat (Tartu) University, who worked in Russia for 32 years, was the first to separate forensic chemistry from pharmacy into an independent science and teach it as a separate course. Dragendorff's book “Forensic Chemical Discovery of Poisons” went through 4 editions. He published a pharmaceutical journal in German. He dealt with the issues of isolation and evidence of alkaloids in forensic chemical studies. The general alkaloid Dragendorff reagent is still used today.
Professor N.I.Kromer- a graduate of the University of Dorpat, was the founder of the chemical-pharmaceutical department at the University of Perm, and then - an independent pharmaceutical institute and organizer of forensic medical examination in Perm (in Soviet times).
In pre-revolutionary Russia there were no special laboratories for forensic chemical analysis.
After 1917, the creation of a network of state forensic laboratories with forensic chemical departments began.
In 1918, a medical examination department was organized at the People's Commissariat of Health, the positions of forensic medical experts were established, and the “Regulations on the rights and responsibilities of state forensic medical experts” were developed for the first time.
In 1920, the first departments of forensic chemistry were created at the Chemical-Pharmaceutical Faculty of the II Moscow State University and at the Petrograd Chemical-Pharmaceutical Institute.
In 1934, the State Research Institute of Forensic Medicine was created, which is currently renamed the Center for Forensic Medical Examination under the Ministry of Health of the Russian Federation.
In 1934, the People's Commissariat of Health of the RSFSR approved the first “Rules for forensic medical and forensic chemical examination of material evidence,” which were then periodically updated.
Currently, the Order of the Ministry of Health of the Russian Federation No. 407 of December 10, 1996 “On the introduction into practice of the rules of forensic medical examination” is in force, which regulates the legal and methodological foundations, including forensic chemical examination.
The following made a huge contribution to the development of toxicological chemistry and the improvement of forensic chemical examination in our country:
Professor A.V. Stepanov- founder and head of the first department of forensic chemistry at the II Moscow State University, Master of Pharmacy, Doctor of Biological Sciences, Honored Scientist of the RSFSR. He was one of the main organizers of the Moscow Pharmaceutical Institute, where he was deputy director for scientific affairs and first dean. Worked in the field of forensic chemistry for 45 years. He wrote about 100 scientific papers and 3 textbooks, including a textbook on forensic chemistry that was republished three times. He was involved in training personnel for forensic chemical examination, and for the first time, the department organized specialization and advanced training courses for forensic chemists. His work on the isolation of alkaloids and metal poisons is known,
Professor M.D. Shvaikova, student of A.V. Stepanova, who after his death in 1946 headed the department of forensic chemistry and directed it for 30 years. M.D. Shvaikova continued and successfully developed all scientific directions created by A.V. Stepanov. She has trained 30 candidates of pharmaceutical sciences in the field of forensic chemistry; a textbook was written on forensic and then on toxicological chemistry, which went through three editions.
The centers of scientific thought in the field of toxicological chemistry in the Russian Federation are the Forensic Medical Examination Center under the Ministry of Health of the Russian Federation, departments and courses of toxicological chemistry at pharmaceutical universities in the country, where M.D. Shvaikova’s students still work.
Advances in the field of toxicological chemistry are closely related to the general advances in chemical and toxicological sciences. The latest methods of analytical chemistry are widely used in toxicological chemistry.
Main sections of toxicological chemistry are biochemical and analytical toxicology.
The modern development of toxicology shows that understanding the mechanisms of the toxic effects of substances on the body is impossible without a systematic approach. An organism is a complex biosystem, a collection of interacting parts. The toxicity of a substance is inextricably linked with the kinetics of its absorption, distribution, excretion, the mechanism of metabolic reactions, etc., therefore it is necessary to pay special attention to the main pathways and mechanisms of transport, quantitative patterns that determine the relationship between the chemical properties and biological activity of substances. All these questions form the basis biochemical toxicology.
Issues of the kinetics of foreign compounds, the main patterns and parameters of their distribution, the processes of absorption and excretion, the kinetics of excretion from the body are discussed in detail in the course of pharmacology.
Issues of biotransformation of foreign compounds in the body, stages and pathways of biotransformation reactions, factors affecting metabolism are discussed in the course of biological chemistry.
Information about the physicochemical characteristics of toxic substances allows one to correctly navigate the degree of their toxicity, the variety of chemical transformations that occur with a toxic substance in the body, as well as assess the toxic situation associated with the entry of a toxic substance into the human or animal body.
Analytical toxicology is the main and main section of toxicological chemistry, which examines the methods and methods of chemical analysis as applied to biological objects. The main issue of analytical toxicology remains, as before in forensic chemistry, the consideration of issues related to the preparation of samples (objects), including the isolation (isolation), purification and concentration of toxic compounds from a variety of biological objects, as well as the correct use for qualitative and quantitative determination of capabilities various methods of analysis, their rational combination.
Chemical toxicological analysis (CTA) is extremely responsible and has its own specific characteristics (this is what makes toxicological chemistry an independent pharmaceutical discipline).
Features of chemical-toxicological analysis.
1. Extreme diversity and diversity of research objects: these are biological fluids (blood, urine), vomit, internal organs of human corpses, hair, nails, remains of food and drinks, medicines, pesticides, household chemicals, dishes, household items , clothing, water, earth, etc.
2. The need to isolate (extract) small quantities (from μg to mg) of the desired chemical substances from a relatively large amount of the research object is the second and main specific feature of CTA. The further course of chemical analysis and even its results often depend on isolation methods.
3. In the vast majority of cases, a toxicological chemist has to work with trace amounts of a chemical substance, which, as a rule, is not chemically pure, but is mixed with accompanying (coextractive, ballast) substances that are extracted during isolation and often have a negative effect on the results of the analysis. It is necessary to remove these ballast substances by introducing additional cleaning methods.
4. Establishing the presence of a toxic substance in the body and the ability to judge its quantity requires appropriate, sometimes special, but always the most sensitive and specific methods of analysis.
5. A kind of peculiarity is the need for a correct assessment of the results of the analysis - an expert opinion. The expert has the opportunity to speak only about the detection or non-detection of the sought-after substance, because, based on the nature of the chemical substance, taking into account the sensitivity of the methods used, a negative test result does not always indicate the absence of a toxic substance (traces of it may remain in the object, but not be detected) . Conversely, some of the substances that toxicology indicates as toxic are natural constituents of the body (Cu, As, Hg, Zn, Pb cations, etc.). They can be detected and determined during the analysis process, but do not cause poisoning.
The presence of a toxic substance is not always evidence of its introduction into the body for the purpose of poisoning, because many of them, for example, barbiturates, alkaloids and other nitrogen-containing substances of a basic nature, are medicinal. In these cases, quantitative assessment is mandatory.
6. Difficulties in detecting and identifying a toxic substance, especially in the organs of a corpse, are also due to the behavior of the chemical substance in the body and corpse. A toxic substance introduced into the body is most often distributed unevenly throughout fluids and tissues. Many substances, especially of an organic nature, are further subjected, mainly in the liver, to various processes of biotransformation (metabolism) along the path of hydrolysis, oxidation, reduction, synthesis with the biochemical components of the body (conjugation with glucuronic, sulfuric acids), aimed mainly at neutralization of the substance. Processes of elimination (excretion) of a toxic substance and its metabolites by the kidneys, urine, etc. occur. Depending on the depth of biotransformation, a larger or smaller part of the substance remains unchanged or is metabolized, and depending on the intensity and rate of elimination, a larger or smaller part of the substance eludes the researcher. These factors have a significant impact on the results of the analysis.
Chemical toxicological analysis is used to solve problems in two main directions:
-- forensic chemical examination as an application of knowledge of toxicological chemistry to the practical solution of issues raised by forensic investigative bodies (most often in case of death, the objects in this case are the internal organs of a corpse).
Forensic chemical examination is carried out at the request of judicial investigative authorities, and the objects of forensic chemical examination are called “physical evidence”.
The Criminal Procedure Code of the Russian Federation (CPC RF) gives the following definition:
Physical evidence are objects that served as instruments for committing a crime or retained traces of a crime or were objects of criminal actions of the accused, as well as money and other valuables acquired by criminal means, and all other objects and documents that can serve as a means of detecting a crime and establishing factual circumstances case, identifying the perpetrators, or to refute the crime or mitigate the guilt of the accused.
Depending on the nature of the physical evidence and the questions posed, forensic chemical examination is carried out either in the forensic chemical departments of forensic laboratories of the bureau of forensic medical examination of health authorities, or in special forensic laboratories of the ministries of justice and internal affairs.
- analytical diagnostics of acute poisoning and drug addiction. The objects in this case are biological fluids of the human body (blood, urine, saliva, cerebrospinal fluid), as well as residues of medicinal and chemical substances, dishes and other objects, plants, etc.
Issues of analytical diagnostics of acute poisoning and drug addiction are resolved in chemical and toxicological laboratories of centers for the treatment of acute poisoning, toxicology centers and departments, extracorporeal therapy centers, drug treatment clinics and other health care institutions.
Organizational structure of forensic medical and forensic chemical examination in the Russian Federation
In the healthcare system, the leadership of the entire forensic medical and forensic chemical service in scientific, practical and organizational terms is carried out by the Chief Forensic Medical Expert of the Ministry of Health of the Russian Federation. Administratively, the Chief Expert reports directly to the Minister of Health of the Russian Federation or his first deputy, and in scientific and practical terms, he is associated with the Center for Forensic Medical Examination at the Ministry of Health of the Russian Federation, being its director.
In scientific and practical terms, the chief and senior forensic experts of the autonomous republics, territories and regions are subordinate to the Chief Forensic Medical Expert of the Russian Federation, and inter-district, district and city experts are in turn subordinate to them. Administratively, they are all subordinate to the relevant local health authorities.
Chief forensic experts of the republics, territories and regions; senior city (Moscow, St. Petersburg) experts are the heads of the Bureau of Forensic Medicine (BSME), they are appointed and removed by the heads of the relevant health authority.
The SME Bureau consists of three departments:
1. Forensic medical outpatient clinic (department for examining living persons).
2. Morgue (department of forensic medical examination of corpses).
3. Forensic laboratory (department for the study of material evidence), including 3 departments:
a) forensic biological
b) physical and technical
c) forensic chemical
Forensic chemical examinations (research) are carried out in the forensic chemical department of the forensic laboratory of the Bureau of Forensic Medicine (SHO SML BSME). The position of the expert is currently called: doctor, forensic expert of the forensic chemical department of the BSME.
The procedure for appointing a forensic chemical examination (as well as others) is provided for by the Code of Criminal Procedure of the Russian Federation. According to the Code of Criminal Procedure, an expert can be called at any stage of the preliminary or judicial investigation and must give an objective opinion on the questions put to him. For refusal or evasion of an expert or failure to appear without good reason when summoned by judicial investigative authorities, or for giving a knowingly false conclusion, the expert bears criminal liability in accordance with the law.
Legal and methodological foundations of forensic chemical examination
The legal and methodological foundations of forensic chemical examination are currently regulated Federal Law No. 73-FZ of May 31, 2001“On state forensic activity in the Russian Federation” andOrder of the Ministry of Health of the Russian Federation No. 161 of April 24, 2003 “On approval of the Instructions for organizing and conducting expert research in the forensic medical examination bureau.” The previously existing order of the Ministry of Health of the Russian Federation No. 407 of December 10, 1996 “On the introduction into practice of the rules for the production of forensic medical examinations” is considered no longer in force.
Seizure of objects for forensic chemical research:
· In order to detect and quantify toxic substances for SCN, various internal organs, blood and urine are removed and sent, taking into account the nature of the poison and the routes of its introduction into the body, distribution, routes and speed of elimination, duration of intoxication and therapeutic measures. They also send vomit, the first portions of rinsing water, remains of medicinal and chemical substances, food, drinks and other objects.
· If poisoning with a toxic substance is suspected, a complex of internal organs is sent: the stomach with its contents, 1 m of the small intestine, 1/3 of the liver, 1 kidney, all urine and at least 200 ml of blood.
· If there is a suspicion that poison has been introduced through the vagina or uterus, the uterus and vagina are additionally directed separately.
· If subcutaneous or intramuscular injection is suspected, a section of skin or muscle from the area of the injection site.
· If inhalation administration is suspected - 1/4 of the lung, 1/3 of the brain.
· If grains, crystals, or tablets are found in the stomach contents, they are also sent for examination.
Additionally They are sent to the specified complex of internal organs and biological fluids in case of suspected poisoning:
· acids, alkalis - pharynx, trachea and esophagus, areas of skin with traces of the action of poison.
· volatile organochlorine substances (chloroform, carbon tetrachloride, dichloromethane, organochlorine pesticides and other alkyl halides) - omentum, 1/3 of the brain.
· methyl alcohol – 1/3 of the brain
glycosides - 1/3 of the liver with gall bladder
organophosphorus compounds - necessarily blood (to determine cholinesterase activity)
· mercury salts - rectum, hair
Chronic poisoning with lead compounds, thallium - flat bones
Chronic poisoning with arsenic compounds - hair, nails, flat bones
· tetraethyl lead - brain and lungs
carbon monoxide - blood, muscle tissue
· ethanol - blood from large veins, urine, if impossible - about 500 g of muscle tissue
methemoglobin-forming poisons (aniline, nitrobenzene, potassium permanganate, formaldehyde, chromates, acetaldehyde) - blood for methemoglobin
· mushrooms and poisonous plants - undigested pieces from the contents of the stomach, vomit, rinsing water
Organs should not be washed with water or contaminated with chemicals or mechanical impurities. Organs are placed in dry glass containers (metal or ceramic containers are prohibited).
The expert must ensure that the poison is not removed from the corpse and does not enter it from the outside.
Objects are preserved only if poisoning with cardiac glycosides, phenothiazine derivatives, FOS, alkaloids and tricyclic antidepressants is suspected. Rectified alcohol is used; in jars its level must be at least 1 cm high. At the same time, a sample of alcohol taken from the same container as for canning is sent for testing.
The jars are hermetically sealed, labeled according to the standard form, and together with the records are placed in a sealed plastic bag, which is immediately sent for research.
At the same time, a resolution is sent to the SHO to order a forensic chemical examination of the corpse: the direction of a forensic expert with a brief statement of the circumstances of the death, the main data of the pathological examination of the corpse with the diagnosis, surname, initials and age of the deceased, as well as issues to be resolved by the chemical expert.
When examining an exhumed corpse, 500 g of soil taken from 6 places (above and below the coffin, near its side surfaces, at the head and foot ends), as well as pieces of clothing, upholstery, bedding, and the bottom board of the coffin are sent for forensic chemical analysis. about 500 sq. cm), various decorations and objects found near the corpse.
Rules for the conduct of forensic chemical examination of material evidence in the SKhO LSU Bureau of Forensic Examination of Health Authorities
Purpose and objects of forensic chemical examination (research):
SCE (research) is carried out for the purpose of isolating, identifying and quantifying or eliminating toxic, narcotic and potent substances, products of their transformation, mainly in organs and biological fluids of the human body, as well as in pharmaceuticals, food products, drinks, the human environment environment and objects. An important part is the interpretation of the obtained SCN results.
Tasks of forensic chemical examination:
n determination of toxicologically important substances to determine the cause of death
n identification of medicinal and narcotic substances that can affect a person’s condition
n qualitative and quantitative analysis of narcotic substances in biological material and other samples relevant for forensic medical and forensic investigative practice
n to obtain analytical results, the subsequent interpretation of which may be useful for forensic investigative authorities, paramount importance is attached to the correct selection, seizure and direction of objects for forensic chemical examination
Grounds for conducting forensic chemical examination (research):
n forensic chemical examination of material evidence is carried out on the basis resolutions bodies of inquiry and investigation, court rulings
n forensic chemical studies of internal organs, tissues, biological fluids of human corpses can be carried out according to written directions forensic experts
n Forensic chemical examination of biological fluids, human secretions, and swabs from the surface of the skin in cases of suspected poisoning or non-medical use of narcotic and other drugs is carried out according to doctors' referrals narcological clinics and other medical institutions.
Along with the material evidence, they send documentation:
n resolution of the bodies of inquiry or investigation to order an examination or a court ruling, which sets out the circumstances of the case, lists the items sent for examination, and precisely formulated questions requiring resolution
n an extract from the report of the forensic medical examination of the corpse, containing preliminary information, basic data of the examination of the corpse and indications of the purpose of the study, signed by a forensic expert
n a copy of a hospital patient’s card certified by a medical institution, if the victim used medical care
n during repeated examinations, a certified copy of the “Act of (primary) forensic chemical research” is sent.
n Note: Simultaneously with the research objects, an act of taking samples is sent from drug treatment clinics, indicating the persons in whose presence the objects were taken (witnesses), the signatures of the persons being examined, as well as the persons sending the objects for research and taking the samples.
Responsibilities and rights of persons admitted to perform forensic chemical examination:
n Forensic chemical examinations are carried out by persons authorized to occupy positions doctor forensic expert SHO who have undergone special training in toxicological chemistry
n Forensic medical experts of agricultural organizations must improve their theoretical level and professional qualifications in advanced courses at least once every five years
n the responsibilities of a forensic medical expert include:
¨ reception of material evidence and documents related to it
¨ control over registration of examinations
¨ carrying out forensic chemical examinations at the current level of scientific achievements and on time
¨ keeping records in a work journal
¨ carrying out advisory work within its competence with persons who sent objects and conducting investigations of criminal cases
¨ drawing up a “forensic chemical research report”
¨ ensuring the safety of material evidence, research objects and examination documents
Laboratory premises
Forensic chemical examinations are carried out in rooms specially equipped for chemical work. Access to the laboratory should be limited to unauthorized persons. The premises must comply with sanitary and safety standards, must be isolated from other departments of the Bureau and, upon completion of work, be locked and sealed with the seal of the department.
Reception and storage of research objects (material evidence) and accompanying documents.
1. Objects of research (physical evidence) are received through the office of the Bureau or directly to the SKhE in accordance with the rules for sending cadaveric material to the SKhE:
Objects are registered along with documents for them in the registration journal of the agricultural organization (the journal must be numbered, laced, sealed and signed by the head of the agricultural organization).
Objects are subjected to a detailed inspection and description, noting the nature of the packaging, inscriptions, printing, checking compliance with the data specified in the direction (resolution)
2. Physical evidence before the start of a forensic chemical examination, during the analysis and until its completion is stored in conditions that ensure their safety:
Not subject to rotting - in a closed, sealed metal cabinet,
Those subject to rotting (internal organs, biological fluids) - in a hermetically sealed container in the refrigerator, which is sealed at the end of work.
3. Upon completion of the examination:
Objects that are not subject to decay are returned along with a conclusion to the institution that sent them
Those subject to rotting are left for storage in the agricultural storage facility for one year after the end of the examination, after which they are destroyed in accordance with the “Rules of storage and destruction...” (objects received for examination for the presence of ethanol only are destroyed one month after the end of the analysis)
Accompanying documents x
The final stage of forensic chemical analysis is the drawing up of an expert opinion or a forensic chemical research report. According to the order of the USSR Ministry of Health (No. 694 of July 21, 1978), when conducting a forensic chemical examination of material evidence on the basis of a resolution of the internal affairs bodies, the prosecutor's office or a court ruling, an “Expert Conclusion” is drawn up, and when the objects under study are sent by forensic experts a “Forensic Chemical Research Report” is drawn up. Both of these documents have the same structure. They are compiled on the basis of a comprehensive and in-depth study of the obtained analysis results and entries in the work log.
The report (conclusion) of a forensic chemical investigation is drawn up in a certain form and consists of 4 sections: an introductory part, a description of physical evidence, a chemical examination and expert conclusions.
The introductory part indicates on the basis of which documents the research was carried out, the laboratory in which the research was carried out, the position, last name, first name and patronymic of the expert, work experience and category; material evidence regarding the poisoning is listed (the surname, name and patronymic of the deceased are indicated); the start and end dates of the study are noted, and the issues to be resolved are listed. After listing all these issues, the circumstances of the case are outlined and information from the documents received (including medical ones) is provided.
The section “External inspection” describes in detail the objects received, their quantity, container, packaging, sealing, inscriptions on labels, appearance of each organ, color, smell, reaction of the environment, weight. The conformity of the delivered packages with their description in the accompanying document, the absence or presence of packaging violations are noted.
In the section “Chemical research”, based on entries in the work log, the mass of the organ (object) used for analysis, the methods used, research methods, reactions, instruments and reagents are described in detail; the total volumes of mineralizates, distillates, dialysates and the volumes consumed for individual reactions are noted, and calculations of the results of quantitative determination are noted. Writing chemical formulas and references to the authors of methods and reactions are not allowed.
In the “Conclusion” section, the compounds found during the study of each organ are first indicated, their quantities in milligrams in recalculation per 100 g of organ, a forensic chemical assessment is given of the results of the study, taking into account the resolving capabilities of the method of isolating the found substance and the method of its quantitative determination, and it then lists all compounds tested for which negative results were obtained. In the conclusion, answers to the questions posed are given.
The report on the quantitative determination of ethyl alcohol in blood and urine is drawn up in an approved form.
The report of the forensic chemical investigation (examination report) is printed in two copies, signed by the expert, and the date of execution is indicated on it. The completed document is sealed. One copy of the act indicating the number with the accompanying document is sent to the appropriate authority. The accompanying document indicates the number of the case on which the investigation was carried out, the last name, first name and patronymic of the deceased, a list of returned, abandoned or completely consumed material evidence, returned documents (number of sheets), the accompanying document is signed by the head of the forensic medical examination bureau and the head of the forensic medical laboratory. The second copy of the conclusion (act) is stored in the archives of the forensic medical examination bureau.
SOME ISSUES OF TERMINOLOGY IN TOXICOLOGICAL CHEMISTRY
Most of the terms used in toxicological chemistry are mainly borrowed from pharmacy, toxicology, analytical chemistry and a number of other disciplines. However, in toxicological chemistry there are still terms that may seem familiar, but their meaning is not always certain. This leads to the incorrect use of some terms and makes it difficult for them to be understood even by specialists in this field of science and related disciplines. Such terms in toxicological chemistry include: extraction, extract, extract, isolation, isolation, etc.
In the literature on toxicological chemistry, the liquid obtained after infusion of biological material with acidified water or acidified ethyl alcohol is called an extract by some authors, an extract by others, and an extract by others.
The term extraction used in this case is unsuccessful. In analytical chemistry and in a number of other chemical disciplines, the term extraction is the name of one of the widely used analytical operations (extraction, boiling, heating, centrifugation, filtering, straining, etc.). Some toxicological chemists call aqueous or alcoholic extracts from biological material an extract. This name for hoods is also unfortunate. Toxicological chemistry belongs to a series of special pharmaceutical disciplines studied in higher pharmaceutical educational institutions. In pharmacy, extracts were used for medicinal purposes even before the advent of toxicological chemistry as a science. It is known that extracts are mainly obtained from plant materials; they have a certain consistency (thick, liquid, dry, etc.).
Aqueous and alcoholic extracts from biological material have nothing in common with extracts used in pharmacy, neither in purpose, nor in preparation method, nor in consistency. Therefore, one cannot equate extracts obtained in pharmacy with extracts obtained by infusing biological material with acidified water or acidified ethyl alcohol.
In addition, in chemistry and chemical technology, extraction (in the solid-liquid system) is the process of extracting substances from solids with organic solvents. The process of extraction with water is called leaching (see Chapter 3, § 1). Toxicological chemistry mainly uses methods for isolating toxic substances based on their extraction from biological material with acidified water (i.e., leaching processes rather than extraction). Therefore, liquids obtained by extracting toxic substances from biological material with acidified water or acidified alcohol cannot be called extracts; they should be called extracts.
In chemical toxicological analysis, the process of isolating toxic substances from biological material is sometimes called the isolation process, although these terms have different meanings.
Isolation is the process of transferring toxic substances from the corresponding objects into the liquid phase (into the extract, distillate, mineralizate, etc.). To isolate toxic substances from objects that are liquids, the extraction method is mainly used (transfer of the test substance from the aqueous phase to the phase of an organic solvent that is immiscible with water). Less commonly, steam distillation is used for this purpose.
Isolation of the test substances from the corresponding objects is carried out in two stages. First, the substances under study are isolated and then purified. Thus, the isolation of substances from the objects under study is one of the stages of their isolation from the corresponding objects.
In recent years, some toxicological chemists have been trying to introduce the term chromogenic reactions into toxicological chemistry. This is not a new type of reaction. These reactions have long been used in analytical chemistry under the name color reactions. The term "chromogenic" comes from the Greek. chroma, which means coloration (color). The question arises: what caused the attempt to replace the understandable expression color reactions with the foreign term “chromogenic reactions” (without translating it into Russian)?
The same can be said about the term aliquot. Some toxicological chemists use this term to replace the word liquid, others call aliquot the liquid above the sediment, and some understand an aliquot as a solution of a dry residue or a certain part of a liquid. With such uncertainty in the term aliquot, there is hardly any need to use it instead of Russian words that are understandable to everyone (solution, liquid, etc.).
Forensic chemical examination (examination) of physical evidence is carried out in accordance with the legislation of the USSR and union republics on health care, criminal and criminal procedural codes of union republics, orders and regulations of the USSR Ministry of Health.
Forensic chemical examination (research) is carried out with the aim of detecting and quantifying or eliminating substances that, under certain conditions, can cause human death or health problems. It can help improve the quality of medical care for
intoxication and prevention of poisoning with certain poisons in various regions of the country.
Forensic chemical examination (examination) of physical evidence is carried out on the basis of decisions of the bodies of inquiry and investigation or court rulings, as well as on the orders of forensic experts.
Separate studies can be carried out upon written referrals from medical institutions in order to establish the intake of a substance toxic to the human body, to conduct and evaluate the effectiveness of treatment.
Forensic chemical examinations and research are carried out in the forensic chemical departments of the forensic laboratories of the bureau of forensic medical examination of health authorities.
In the forensic chemical departments of the forensic laboratories of the ministries of health of the Union republics, both primary and repeated studies are carried out.
At the Scientific Research Institute of Forensic Medicine of the USSR Ministry of Health, particularly complex primary examinations and studies and re-examinations are carried out.
The resolution ordering a forensic chemical examination must indicate: brief circumstances of the case, objects sent for examination, and precisely formulated questions requiring resolution.
The following must be sent along with the resolution:
an inventory of physical evidence with a detailed description of each object, shape and volume of vessels, closures, sealing and label text;
Physical evidence along with documents is received by the forensic chemical department only through the office of the forensic medical examination bureau with the appropriate written instructions from the head of the bureau on the decision to conduct a forensic chemical examination or on the accompanying document of the forensic medical expert.
Physical evidence from the office of the bureau in unopened form is received against receipt by the forensic chemical department.
Physical evidence unpacked and unsealed or with damaged packaging, received from the city, incl.
where a forensic medical laboratory operates, must be returned to the institution that sent them for examination. This requirement does not apply to objects received from other localities. A report is drawn up regarding improper packaging or its violation, one copy of which is sent to the institution that sent the research objects, and a forensic chemical examination is carried out.
Physical evidence and accompanying documents are registered in the registration journal of the forensic chemical department in a form approved by the USSR Ministry of Health.
Material evidence received by the forensic chemical department is carefully examined by a chemical expert and described in detail in a work log.
The chemical expert must establish a complete match of the objects received with their description in the decision on the appointment of a forensic chemical examination or in the accompanying document.
In the absence of individual objects and when objects not specified in the resolution or accompanying document are discovered, an act is drawn up.
The expert chemist is responsible for the safety of research objects from the moment they are received. He keeps detailed notes in a work journal, in which, in addition to describing the physical evidence, all data on the processes carried out, reactions and results obtained, including all materials on quantitative determination, are entered on a daily basis.
An expert chemist carefully studies all materials related to the examination and draws up a research plan. Forensic chemical research is carried out for a specific compound or group of substances specified in the resolution or accompanying document.
If the materials of the case and the data from the study of objects indicate the need to conduct an analysis for other substances, then the chemist expert is obliged to expand the study.
In the absence of an order to conduct an analysis for a specific substance, the study is carried out according to the scheme of a general forensic chemical study in accordance with the list of toxic substances determined by order of the USSR Ministry of Health.
Only part of the physical evidence is used for analysis, the second part can be used to check the results by the same chemical expert, the third part is returned or stored in the laboratory for re-analysis, which is carried out in another laboratory, if the need arises.
When limited quantities of physical evidence are obtained, they can be used in full. This is indicated in the accompanying document to the examination report.
Particular care must be taken when consuming distillates, minerals, extracts and other objects.
All forensic chemical studies should be conducted as quantitative, since they can be turned into such at each stage of the work.
In forensic chemical analysis, only those methods and reactions should always be used for research, with which the expert has previously become familiar, mastered them, knows all the conditions for their reproduction, and can take into account all the errors that may arise when using them. You cannot learn from forensic chemical research, and to perform it you need to use already studied reactions and methods.
It is impossible to make a conclusion about the presence of a toxic substance in an object based on one reaction or on the basis of the result of one physical and chemical method. The conclusion should be based on the results of several reactions or on a combination of the results of chemical reactions and physicochemical methods.
If there are appropriate methodological recommendations, instructions or information letters from the chief forensic medical expert of the USSR Ministry of Health, their use when conducting forensic chemical examinations should be mandatory.
A forensic chemical examination (research) in one case is carried out by one expert chemist. As an exception, individual examinations can be carried out by several chemical experts, but with strict delimitation of the objects of research.
At the same time, a chemical expert can conduct no more than two forensic chemical examinations (research), but he cannot perform the same operations on different cases.
All operations and processes related to the isolation, detection and quantification of toxic substances in forensic chemical research are not permitted.
RULES
carrying out the examination of material evidence in the forensic chemical departments of the laboratories of the forensic medical examination center
1. Purpose, objectives and objects of forensic chemical examinations (research)
2. Grounds for conducting forensic chemical examination (research)
3. Documents sent along with material evidence
4. Persons performing forensic chemical examinations, their responsibilities and rights
5. Premises and equipment for forensic chemical examinations
6. Reception and storage of material evidence and accompanying documents
7. The procedure for conducting a forensic chemical examination
8. Methodology of forensic chemical analysis
9. Documentation during forensic chemical examinations
1. Purpose, objectives and objects of forensic chemical examinations (research)
1. Forensic chemical examinations (research) are carried out for the purpose of isolating, identifying and quantifying or eliminating toxic, narcotic and potent substances, products of their transformation, mainly in organs and biological fluids of the human body, as well as in pharmaceuticals. An important part of forensic chemical analysis is the interpretation of the results obtained.
2. Tasks of forensic chemical examination:
1) determination of toxicologically important substances to establish the cause of death;
2) identification of medicinal and narcotic substances that can affect a person’s condition;
3) qualitative and quantitative analysis of narcotic substances in biological material or other samples relevant for forensic medical and forensic investigative practice;
4) obtaining analytical results, the subsequent interpretation of which can be useful for forensic investigative authorities; paramount importance is attached to the correct selection, seizure and direction of objects for forensic chemical examination.
2. Grounds for conducting forensic chemical examination (research)
3. Forensic chemical examination of physical evidence is carried out on the basis of a resolution of the investigative bodies, the prosecutor's office or a court ruling.
4. Forensic chemical studies of internal organs, tissues, and biological fluids of human corpses can be carried out following written directions from forensic medical experts.
5. Forensic chemical studies of biological fluids, human secretions, and swabs from the surface of the skin in case of suspected poisoning associated with the consumption of narcotic or other drugs are carried out on the orders of doctors from drug treatment clinics and other medical organizations.
3. Documents sent along with material evidence
6. Along with material evidence, send:
1) resolution of the investigation to order an examination or a court ruling, which sets out the circumstances of the case, lists the items sent for examination and precisely formulated questions requiring resolution;
2) an extract from the report of the forensic medical examination of the corpse, containing preliminary information, basic data of the examination of the corpse and indications of the purpose of the study, signed by the forensic expert;
3) a copy of a hospital patient’s card certified by a medical institution, if the victim received medical care;
4) during repeated examinations, a certified copy of the “Initial Forensic Chemical Research Report” (“Expert Conclusion”) is sent.
Note.
Simultaneously with the research objects, a report on the seizure of objects is sent from drug treatment clinics, indicating the persons who sent the objects for research and who carried out the sampling. If the necessary materials have not been sent, they must be requested, and the study may be delayed until they are received (except in cases of testing for rapidly degradable toxic substances).
4. Persons performing forensic chemical examinations, their responsibilities and rights
7. Forensic chemical examinations are carried out by persons admitted in accordance with the established procedure to occupy the position of a forensic medical expert and a forensic medical expert - head of the department, who have undergone special training in toxicological chemistry.
8. The forensic chemical department is headed by a qualified specialist who ensures the department operates at the proper scientific and technical level, manages the implementation of examinations, controls the work in the department and monitors the improvement of the professional level of employees. The manager provides recommendations and instructions to the employees of the forensic chemical department.
9. Forensic experts of the forensic chemistry department must systematically improve their theoretical level and professional qualifications through advanced courses at least once every 5 years, as well as at special thematic seminars.
10. The responsibilities of forensic experts of the forensic chemical department include:
1) reception of material evidence and documents thereto;
2) control over the registration of examinations of material evidence;
3) carrying out forensic chemical examinations in a timely manner at the level of modern achievements of science and technology;
4) keeping records in a work journal related to the description of material evidence, its packaging and examination;
5) carrying out consulting work within its competence with persons who sent objects (physical evidence) and conducting investigations of criminal cases;
6) drawing up a “Forensic Chemical Research Report” (“Expert Conclusion”) of material evidence and accompanying documents, checking their typewritten texts;
7) ensuring the safety of material evidence, research objects and documents accompanying the examination.
5. Premises and equipment for forensic chemical examinations
11. Forensic chemical examinations of physical evidence are carried out in rooms specially equipped for chemical work, with fume hoods with a ventilation unit, gas and water supply, good natural lighting, heating, ventilation, equipped with a power line and a ground loop. Access to the laboratory should be limited to unauthorized persons.
12. The premises must comply with sanitary standards and allow work to be performed at a modern scientific level. The department must provide conditions for working with infected and toxic material. The forensic chemistry department includes: premises for laboratory places for specialists, apparatus and equipment (including refrigeration units, freezers, centrifuges, etc.), offices for specialists, a washing room, utility rooms for storing reagents, chemical glassware, and an archive.
13. When equipping the premises of the forensic chemical department, safety conditions must be taken into account.
14. The forensic chemical department must be isolated and sealed with the seal of the department.
6. Reception and storage of material evidence and accompanying documents
15. Physical evidence (research objects) goes directly to the forensic chemical department of the forensic medical examination center (hereinafter referred to as the FME).
16. The correct selection, seizure and direction of objects are reflected in the Rules for the seizure and direction of cadaveric material for forensic chemical research. Objects sent in violation of the current Rules are not subject to examination. This provision does not apply (to avoid damage to the material) to material evidence sent from out-of-town institutions, and they are accepted.
In case of violation of the rules for the seizure, registration and sending of biological objects for forensic chemical research, an act is drawn up in 2 copies, one of which is transferred to the person who sent the material for research, the other is stored in the department. Physical evidence received by the department is recorded, described and examined.
17. Objects sent for forensic chemical research must be sufficient in quantity to carry out the study and possible re-analysis.
18. To comply with precautionary measures when sending objects from infected corpses and living persons with infectious diseases for forensic chemical examination, containers must have special marks, for example, “tuberculosis”, “hepatitis”, “AIDS”, etc.
19. Registration of material evidence and documents thereto received by the department is carried out in the department’s registration journal according to the approved form. The registration book with numbered sheets is laced, sealed, and signed by the head of the department.
20. Physical evidence is subjected to detailed examination and description. At the same time, the nature of the packaging, inscriptions, and printing are noted. They check the compliance of the delivered material evidence with the data specified in the direction (resolution).
21. Physical evidence must be located before the start of a forensic chemical investigation, during its conduct and at the end of the investigation in conditions that ensure the safety of these objects:
1) material evidence that is not subject to decay is stored in a closed and sealed metal cabinet;
2) material evidence subject to decay (internal organs, biological fluids) is stored in hermetically sealed containers placed in a refrigerator or freezer, which are sealed at the end of the work;
3) material evidence that is toxic and potent substances is stored in compliance with the Rules for the reception, storage, use and dispensing of toxic and potent substances in the forensic laboratories of the Republican Center for Medical Examinations.
At the end of the examination, material evidence that is not subject to decay is returned in sealed form along with the “Expert’s Conclusion” through a person entitled to receive it, or sent to the institution that sent it by mail.
22. Material evidence that is subject to decay (internal organs, parts of corpses, secretions of the human body, etc.), if they cannot be returned to the court or investigative authorities due to the complexity of their further storage in these organizations, are left for storage in the judicial department. chemical departments within one year after the end of the examination (subject to storage conditions). If there are no storage conditions, they must be destroyed one month after the end of the study.
Note.
Due to the influence of decay processes on the determination of ethanol in cadaveric material, blood, urine and internal organs received for testing for the presence of only ethanol are subject to destruction as an exception 30 days after the end of the study.
23. In some cases, material evidence may be destroyed earlier than the established period, with the written permission of a forensic expert or judicial investigative authorities.
24. At the end of the storage period, material evidence and other objects are destroyed in accordance with the current Rules for the storage and destruction of material evidence in forensic laboratories.
25. Upon completion of the examination, accompanying documents are stored in the archive along with a copy of the “Expert’s Conclusion” (“Report”).
7. The procedure for conducting a forensic chemical examination
26. Forensic chemical examination of physical evidence should begin on the day it is received, taking into account the possibility of volatility and decomposition of some substances (organic solvents, acids, alkalis, hydrocyanic acid, atropine, cocaine). If this is impossible for objective reasons, then the material evidence is stored in the refrigerator.
27. The material evidence received by the forensic chemical department is carefully examined by an expert and described in detail in the work log.
28. The expert must establish full compliance of the received objects with their description in the accompanying document and their affiliation.
29. The expert carefully studies all materials related to the examination and draws up a research plan.
30. To conduct a forensic chemical study (detection, application of confirmatory methods, quantitative determination), two-thirds of the sent material evidence (objects) is used and one-third is stored in the laboratory (archive) for re-analysis, if such a need arises.
31. When obtaining a limited amount of material evidence, it can be used in full, in agreement with a forensic expert or judicial investigative authorities.
8. Methodology of forensic chemical analysis
32. The main task of forensic chemical examination is to select the optimal method for isolating a substance. For the detection and identification of chemical and medicinal substances, there are both preliminary methods (color reactions, thin layer chromatography, immunoenzyme methods) and confirmatory instrumental ones (spectrophotometry in the visible, UV (ultraviolet) and IR (infrared) zones, atomic absorption spectrophotometry , gas-liquid chromatography, high-performance liquid chromatography, gas chromatography-mass spectrometry).
When using UV spectrometry, the influence of metabolites and other contaminant coextractants, as well as the sensitivity and lack of specificity of the method, should be taken into account.
When using gas and liquid chromatography, an internal standard method should be used to reduce errors due to surface absorption, losses during extraction, solvent evaporation, derivatization, and impreproducibility due to different injection techniques.
The internal standard must have physicochemical properties similar to the analyte. The chromatographic properties of the internal standard must be such that it elutes with the analyte and is distinct from other substances that may be present. If possible, a homologue of the analyte should be used, which should also be dissolved and mix evenly with the sample being analyzed.
33. Many drugs and other toxicologically important substances are metabolized in the body and converted into polar and conjugated metabolites, which, due to their low volatility, are difficult to identify by gas chromatography. In addition, the conjugates are difficult to extract by conventional extraction methods, so it is preferable to destroy the conjugates by acid hydrolysis before extraction, and then extract the metabolites, subject to derivatization to improve thermal stability and increase their volatility.
However, it is worth considering that some substances undergo changes during the mentioned analytical procedures (acid hydrolysis, derivatization, thermal transformations during the gas chromatographic process, etc.), and this should be an additional feature for the identification of native substances and their metabolites.
34. The study can be carried out for a specific compound, a group of substances, or for an unknown substance according to the scheme of a general forensic chemical study, depending on the questions posed in the accompanying document.
35. If during the study there is a need to conduct analysis for other substances, the expert is obliged to expand the study.
36. For research, you should always use only those methods and procedures that the expert has previously familiarized himself with, owns them, knows all the conditions for reproduction, and can take into account all the errors that arise when using them. Any changes to a method or procedure must be clearly documented and the reasons for the change explained. All changes must be approved by the head of the department.
37. The department should have developed recommendations for all standard techniques used. All methods must be tested. The use of methodological guidelines from the system of the Ministry of Health of the Kyrgyz Republic should be mandatory. Any changes to methods must be motivated and justified.
38. Depending on the assigned tasks, an appropriate analysis scheme is developed. If the analysis is aimed at detecting one poison or a group of substances, then specially developed private methods are used. Where possible, at least two independent methods, each based on different physical or chemical principles, should be used for reliable identification. If it is necessary to detect or exclude a wide range of poisons without a special task (the general course of analysis for an “unknown substance”), then it is necessary to apply an integrated approach for a systematic course of research, the purpose of which is to detect toxic substances, their identification and quantification. To do this, a screening analysis should be carried out followed by the use of confirmatory methods based on various analytical principles. The results of each method are compared with corresponding data, which allows the range of suspected substances to be narrowed. If any compound is detected, to reliably identify the latter, it is necessary to carry out a comparative analysis of the suspected toxic substance with the corresponding standard of the genuine substance or apply the method of additives to biological material, as well as take into account the results of a control experiment.
39. Each forensic chemical study should be conducted as a quantitative study, into which it can be turned at any stage of the work. Objects for all tests are taken by weight, number of distillates; dialysates, filtrates - by volume.
40. Quantitative determination is carried out in all cases where this is possible and appropriate determination methods are available. The amount of substances found refers to 100 g of a sample of the object taken for analysis, and is expressed in weight units.
41. All methods of quantitative determination must be tested on the biological matrix that will be used for analysis (blood, urine, organ tissue), to which a known amount of a substance is added and subjected to research according to this analysis scheme. At the same time, the limits of detection and determination, the absolute yield at various concentrations, the range of determined contents for the calibration graph (subordination to the Lambert-Beer law), selectivity, and reproducibility of the analysis are determined. To increase the accuracy of determining the detected substance, at least two determinations are carried out for each object.
42. It is necessary to ensure the chemical purity of the reagents used for analysis, while the purity of the reagents is checked in the maximum quantities in which they will be used for analysis and by the same methods and reactions that will be used during the forensic chemical investigation.
43. To ensure high quality of examination, it is recommended to carry out internal and external quality control, focused on both the method and the substance being determined. Forensic chemistry departments must be licensed (certified).
9. Documentation during forensic chemical examinations
44. Documentation should be prepared in accordance with the current criminal procedural legislation and orders of the Ministry of Health of the Kyrgyz Republic.
45. Each expert must have a workbook where they enter all the necessary data on the research being carried out.
46. For each examination, an “Expert Conclusion” (“Forensic Chemical Research Report”) is drawn up in 2 copies, one of which, upon completion of the examination, is given to the person who appointed the examination, the other is stored in the department’s archives. The “expert’s conclusion” (“Forensic chemical research report”) must have the expert’s signature, seal and completion date.
47. Each “Expert Conclusion” (“Forensic Chemical Research Report”) is accompanied by an accompanying document, which indicates: the number of the “Expert Report” (“Forensic Chemical Research Report”) being transmitted, the case in which the examination was carried out, name and initials of the victim (or deceased); material evidence returned to the institution that sent it; material evidence left in the department; returned documents with a mark on the number of sheets. The accompanying document to the “Act” is signed by the director of the republican center for forensic examination and the head of the forensic chemistry department.
48. "Expert's conclusion" ("Act of forensic chemical research").
When conducting a forensic chemical examination of physical evidence, on the basis of a resolution of the prosecutor’s office or a court ruling, an “Expert Conclusion” is drawn up, and when conducting a forensic chemical examination in the direction of forensic experts or other persons, a “Forensic Chemical Research Report” is drawn up. They are compiled on the basis of a comprehensive study of the results of the analysis, entries in the work log and are intended for the institution (person) that appointed the examination, which necessitates the completeness of the information in these documents.
The “expert opinion” (“Forensic chemical research report”) is drawn up in a certain form and consists of the following sections: introductory part, description of physical evidence (research objects), research part and conclusions (conclusion).
The introductory part indicates on the basis of which documents the examination was carried out; the department in which the study was conducted; position, full name of the expert, work experience, category, list material evidence (objects), indicate the full name of the deceased (victim), note the start and end date of the study, list the issues to be resolved. Then they state the circumstances of the case and provide information from the documents received.
The “expert’s conclusion” (“Forensic chemical research report”) must have the expert’s signature, seal, and completion date.
All precautions must be taken to ensure confidentiality. To do this, the department must develop a form for issuing information and documentation only to an authorized person.
49. For the purpose of a unified approach to accounting for expert work in the forensic chemical departments of the forensic examination center, conditional coefficients for converting forensic chemical studies of unknown substances into complete analyzes have been developed (conventional units are given in the table below).
Recalculation of studies of unknown substances (powders, liquids, etc.) into full analyzes is carried out according to the actual time spent, taking into account the fact that on average about 35 working hours are spent on one full analysis. These parameters may be revised accordingly and in due course.
50. The position of a forensic medical expert in the forensic chemical department in the republican center for forensic medical examination is established at the rate of: 1 position for every 55 complete analyzes per year.
Conversion factors for forensic chemical studies of unknown substances to complete analyzes (conventional units)
┌──────────────────────────────────┬───────────────────────┬──────────┐
│ Research method and organs │ Results │Note│
│ ├──────┬───────┬────────┤ │
│ │ + │ - │ Quantity │ │
│ 1 │ 2 │ 3 │ 4 │ 5 │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│1. Gas chromatography (GTC) │ │ │ │ │
│1.1. Alcohol │ │ │ │ │
│1.1.1. Blood │ 0.04 │ 0.04 │ │ │
│1.1.2. Urine │ 0.04 │ 0.04 │ │ │
│1.1.3. Muscle │ 0.15 │ 0.15 │ │ │
│1.1.4. Distillate │ 0.04 │ 0.04 │ │ │
│1.1.5. Liquid │ 0.04 │ 0.04 │ │ │
│1.2. Carbon monoxide │ 0.10 │ 0.10 │ │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│2. Gas chromatography (GIC) │ │ │ │ │
│2.1. Volatile │ 0.15 │ 0.08 │ 0.20 │ │
│2.2. Medicinal │ 0.30 │ 0.20 │ 0.20 │ │
│2.3. Glycols │ 0.30 │ 0.20 │ 0.20 │ │
│2.4. Acetic acid │ 0.15 │ 0.08 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│3. Gas chromatography (GES) │ 0.30 │ 0.30 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│4. Gas chromatography (GID) │ 0.30 │ 0.30 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│5. HPLC │ 0.30 │ 0.30 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│6. Chromato-mass spectrometry │ 0.30 │ 0.30 │ │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│7. Distillation │ │ │ │ │
│7.1. Alcohol substitutes │ 0.40 │ 0.25 │ 0.20 │ │
│7.2. Acetic acid │ 0.30 │ 0.20 │ 0.20 │ │
│7.3. Glycols │ 0.20 │ 0.20 │ │ │
│7.4. Hydrocyanic acid │ 0.40 │ 0.25 │ 0.20 │ │
│7.5. Fluorine │ 0.60 │ 0.60 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│8. Isolation of medicinal │ │ │ │ │
│substances │ │ │ │ │
│8.1. Water │ 0.40 │ 0.40 │ 0.20 │ │
│8.2. Alcohol │ 0.40 │ 0.40 │ 0.20 │ │
│8.3. Acetonitrile │ 0.40 │ 0.40 │ 0.20 │ │
│8.4. Other organic │ 0.40 │ 0.40 │ 0.20 │ │
│solvents │ │ │ │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│9. Isolation of drugs from │ 0.20 │ 0.20 │ 0.20 │ │
│biological fluids │ │ │ │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│10. Hydrolysis │ │ │ │ │
│10.1. Internal organs │ 0.30 │ 0.30 │ 0.20 │ │
│10.2. Extractions │ 0.30 │ 0.30 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│11. Isolation of pesticides org. │ │ │ │ │
│solvents │ │ │ │ │
│11.1. Ether │ 0.30 │ 0.30 │ 0.20 │ │
│11.2. Hexane │ 0.40 │ 0.40 │ 0.20 │ │
│11.3. Benzene │ 0.40 │ 0.40 │ 0.20 │ │
│11.4. Other solvents │ 0.30 │ 0.30 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│12. Spectrophotometry │ │ │ │To items │
│12.1. UV region and visible │ 0.05 │ 0.05 │ │8, 9, 10, │
│12.2. IR region │ 0.20 │ 0.20 │ │11 one │
│ │ │ │ │spectral-│
│ │ │ │ │naya │
│ │ │ │ │character- │
│ │ │ │ │ristics │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│13. Thin layer chromatography │ │ │ │To points │
│13.1. Without elution │ 0.15 │ 0.05 │ │8, 9, 10, │
│13.2. Elution │ 0.10 │ │ │11 one │
│ │ │ │ │plate │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│14. Reaction │ │ │ │To points │
│14.1. Microcrystalline │ 0.02 │ 0.02 │ │8, 9, 10, │
│14.2. Coloring │ 0.02 │ 0.02 │ │11 one │
│ │ │ │ │reaction │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│15. Destruction │ 0.40 │ 0.40 │ 0.10 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│16. Mineralization │ 0.40 │ 0.40 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│17. Ashing │ 0.30 │ 0.30 │ 0.10 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│18. Dialysis │ 0.40 │ 0.30 │ 0.20 │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│19. Spectrophotometric │ 0.15 │ 0.15 │ │ │
│definition of SON │ │ │ │ │
├──────────────────────────────────┼──────┼───────┼────────┼──────────┤
│20. Enzyme immunoassay │ 0.05 │ 0.05 │ │ │
├──────────────────────────────────┴──────┴───────┴────────┴──────────┤
│21. Other (based on time spent) 1 p.a. = 25.5 hours │
└─────────────────────────────────────────────────────────────────────┘
