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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5397_Библиотеки_им_академика_М_И_Перельмана
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A. M. A. Ikbal et al.
safeguarding public safety. When used in combination with other analytical methods, FTIR spectroscopy offers a thorough understanding of drug samples that have
been conscated, helping court trials and convictions in drug-related situations
(Agatonovic-Kustrin etal. 2020).
UV-Vis Spectroscopy
The interaction between ultraviolet and visible light and matter is the foundation of
UV-Vis spectroscopy. When electrons go through 2h electronic transitions, molecules
absorb this ultraviolet-visible electromagnetic energy. Different compounds have distinctive absorption spectra because of the difference between energies their ground and
excited states, which is related to the wavelength of light that is absorbed (Alkhuder 2022).
Typically, absorbance (A) versus wavelength (λ) is how UV-Vis spectra are
presented.
Applications for Drug Analysis
1. Quantitative evaluation.
The quantitative investigation of pharmacological compounds in solution is
frequently carried out using UV-Vis spectroscopy. It is based on Beer’s Law,
which asserts that a substance’s absorbance is inversely correlated with both its
concentration and the length of the sample cell (Estupiñán Méndez and
Allscher 2022).
2. Identifying drugs and determining their purity:
Identication: UV-Vis spectra, particularly when paired with reference stan-
dards, can be utilised as an efcient and instructive technique for drug
identication. One chemical from another is distinguished by having distinctive
absorption peaks.
Examining the distinctive peaks in the UV-Vis spectrum might help you
assess the purity of a substance. The spectral signatures of impurities or adulterants can be used to detect them (Ramohlola etal. 2020).
3. Analysis of Pharmaceutical Formulation:
Pharmaceutical businesses must use UV-Vis spectroscopy to guarantee the
reliability and uniformity of drug compositions. The concentration of active
pharmaceutical ingredients (APIs) is evaluated, and formulation stability is
tracked over time.
4. Forensic analysis:
When examining crime scene evidence or dealing with conscated drugs,
UV-Vis spectroscopy is used in the analysis of forensic drug. It contributes to
proving the existence of illegal drugs (Pratiwi and Nandiyanto 2022).
5. Drug Formulation Analysis:
Pharmaceutical businesses must use UV-Vis spectroscopy to guarantee the
accuracy and reliability of drug compositions. Active pharmaceutical ingredients
(APIs) concentration and formulation stability are assessed using it.
6. Forensic investigation.
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When working with captured drugs or examining evidence from crime scenes,
UV-Vis spectroscopy is utilised in the analysis of forensic drug. It contributes to
conrming the existence of illegal drugs.
Benets of UV-Vis Spectroscopy
• High Sensitivity: UV-Vis spectroscopy is suitable for both quantitative and quali-
tative analysis since it is highly sensitive to even trace levels of analytes.
• Speed and effectiveness: UV-Vis measurements are frequently quick, enabling
high-throughput analysis in forensic laboratories.
• Non-Destructive: Since this method does not cause any harm to the sample, it
can still be used for analysis or as proof.
• Wide Range of Applications: UV-Vis spectroscopy is applicable to a wide range
of sample types, such as liquids, solids, and even gases.
• UV-Vis spectroscopy is relatively inexpensive in regards of equipment and con-
sumables when compared to several other analytical techniques (Zhu etal. 2021).
The importance in forensic drug chemistry (Fig.16.1):
One cannot overestimate the value of UV-Vis spectroscopy in forensic drug
chemistry. It performs several vital functions in the context of drug analysis,
including:
• Rapid Substance Identication: UV-Vis spectroscopy offers a quick way to iden-
tify unknown chemicals discovered in seized items or at crime scenes. Forensic
analysts can easily identify the existence of a material by comparing the UV-Vis
spectrum of an unidentied substance to reference spectra.
• Drug Purity Assessment: In criminal investigations, guring out the drug’s purity
is crucial. The purity or safety of a medicine can be impacted by impurities or
adulterants. The strength and form of the absorption peaks can be examined
using UV-Vis spectroscopy to determine the purity of conscated medicines.
• Quantitative Analysis: UV-Vis spectroscopy provides an easy-to-use and trust-
worthy approach for law enforcement authorities to ascertain the precise concen-
tration of a drug. This is crucial for determining the gravity of drug-related
offences (Herrada-Manchón etal. 2020).
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• FTIR, GC-MS, and LC-MS are a few complementary analytical techniques that
are employed frequently alongside UV-Vis spectroscopy to provide a more thor-
ough knowledge of samples of drugs that have been seized. The reliability and
precision of forensic analyses is improved by combining various methodologies
(Sharma etal. 2019).
16.4.4 Microcrystal Tests
Microcrystal tests are a collection of chemical procedures utilised in forensic drug
chemistry to identify and categorise pharmaceuticals and illegal drugs. When a drug
sample reacts with particular reagents, these tests include the production of
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A. M. A. Ikbal et al.
distinctive crystals. Due to their simplicity, speed, and reproducibility, microcrystal
examinations are frequently employed as a rst step in forensic drug investigation
(Tian etal. 2021).
Principle of Microcrystal Tests:
On the basis of the idea that specic chemical substances, when combined with
a drug sample under controlled circumstances, can form distinctive and aesthetically distinct microcrystals, microcrystal tests are used to identify the presence of
drugs. Under a microscope, one may see these microcrystals, which are exclusive to
certain medication classes or unique compounds. The chemical components of the
drug and the particular reagents employed in the test must interact in order for these
crystals to form (Soursou etal. 2023).
The most common microcrystal tests and their uses
1. Scott test.
Application: Barbiturates like pentobarbital and phenobarbital are distin-
guished from each other using the Scott Test.
Principle: A drug sample is dissolved in a solution of sulphuric acid and chloral hydrate. The resultant microcrystals are particular to the kind of barbiturate
that is there (Anzar etal. 2022).
2. The Marquis Test.
Application: Numerous substances are detectable using the Marquis Test,
including opioids (such as morphine, heroin) and amphetamines.
Principle: The drug sample is mixed with a reagent that contains sulphuric
acid and formaldehyde. The resulting microcrystals’ distinctive colours make it
easier to recognise the medication class (Viera-Herrera etal. 2020).
3. Mandelin Test.
Application: Ecstasy (MDMA) and similar amphetamine compounds are
most commonly recognised via the Mandelin Test.
Principle: The drug sample is mixed with a reagent that contains concentrated
sulphuric acid and ammonium metavanadate. The generated microcrystals
exhibit distinctive hues that are unique to MDMA and related substance (Zhu
and Hao 2020).
4. The Froehde Test.
Application: Ecstasy (MDMA) is identied and distinguished from other
compounds using the Froehde Test.
Principle: The drug sample is mixed with a reagent that contains concentrated
sulphuric acid and p-dimethylaminobenzaldehyde. For MDMA, the resultant
microcrystals show unique colour shifts (Mani etal. 2020).
5. Keller-Kiliani test:
Application: Barbiturates are identied and distinguished using the Keller-
Kiliani Test.
Principle: The drug sample is introduced to a reagent that is a combination of
concentrated sulphuric acid and potassium dichromate. In order to identify the barbiturate present, specic microcrystals develop (Sánchez-Viesca and Gómez 2023).
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The importance of forensic drug chemistry:
In forensic drug chemistry, microcrystal assays provide number uses and
advantages.
• Rapid screening: Microcrystal examinations are rapid and can produce initial
results in a matter of minutes, enabling forensic scientists to rank samples for
additional examination.
• Low Cost: These tests are affordable and don’t need expensive equipment, so
even forensic laboratories with little resources can do them.
• Sensitivity: Microcrystal assays are helpful as screening tools because they can
identify medicines even in low quantities.
• Evidence Preservation: Since microcrystal studies normally only require small
amounts of a sample, a signicant amount of the evidence can be kept for follow up analyses or legal proceedings.
• Differentiation: These tests are able to distinguish between medications that
belong to the same class or to locate particular chemicals in complex mixes
(Olsen etal. 2018).
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16.5 Sample Types andEvidence Collection
16.5.1 Biological Fluids (Blood, Urine, Saliva)
In drug-related cases, biological uids are crucial sources of evidence. They offer
vital information on a person’s exposure to and interactions with different chemicals. To guarantee precise and trustworthy results, analysis of these uids calls for
careful procedures and considerations (de Campos etal. 2022a).
Blood
Blood is one of the biological samples that is most frequently used in forensic drug
investigation. It offers a variety of information about a person’s drug use, such as
whether parent drugs and metabolites are present. To maintain the integrity of the
blood samples, extreme caution must be used when collecting them. To avoid contamination or tampering, this entails utilising sterile equipment, adhering to the
right extraction processes, and maintaining a chain of custody.
Following collection, the blood sample goes through a number of analytical procedures. It is done by using methods like mass spectrometry and liquid chromatography to separate and identify the molecules. Forensic chemists can assess the kind
and quantity of chemicals in the bloodstream by comparing the results to established standards (Peters and Wissenbach 2023).
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Urine
Another important biological sample utilised for the analysis of drug is urine.
Compared to blood, it provides a wider window of detection, making it particularly
helpful in situations involving chronic substance use. Utilising specialised containers and following stringent chain of custody guidelines are requirements when collecting urine samples. It is crucial to make sure the sample accurately reects the
individual’s drug exposure.
Utilising methods like gas chromatography-mass spectrometry and immunoassays for urine sample analysis. Immunoassays enable a preliminary check for the
existence of particular drug classes, while chromatography-mass spectrometry provides data that are highly precise and accurate for conrmation (Nicolaou etal. 2021).
Saliva
Recent years have seen a rise in popularity for saliva, a biological sample that is
considerably less invasive. Instances requiring immediate testing, like roadside drug
testing, can beneted from its simple and non-invasive collection. The traces of
chemicals found in saliva samples can reveal information about recent drug usage.
Utilising specialised swabs created to absorb oral uids painlessly while collecting saliva requires their use. The swab is after that delivered to the lab for examination. Utilising methods like liquid chromatography-tandem mass spectrometry
(LC-MS/MS), it is likely to detect and quantify a variety of medications in saliva
(Minho etal. 2023).
A. M. A. Ikbal et al.
16.5.2 Powder andPlant Material Analysis
Powders and plant materials are two common types of substances found in drugrelated instances. In order to examine the presence of prohibited substances and
their purity levels in these items, analysis necessitates the use of a variety of
procedures.
Powder Analysis
Among the most prevalent types of illegal narcotics are powdered compounds. It
is possible to ascertain the chemical make-up and structural characteristics of
powders by using methods like X-ray diffraction (XRD) and Fourier transform
infrared (FTIR) spectroscopy. In order to make a preliminary identication, FTIR
spectroscopy provides knowledge regarding the functional groups that are present. On the other side, XRD assists in the characterisation of compounds like
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designer medicines and adulterants by recognising crystalline structures (Sherma
and Rabel 2019).
Aside from that, powdered substances can have their components separated and
measured using chromatographic methods which involves gas chromatography and
high-performance liquid chromatography (HPLC). For determining the purity levels and locating any potential pollutants, this is essential.
Plant Material Analysis
To identify and measure the active components in cases involving chemicals produced from plants (like cannabis), forensic chemists use a wide range of approaches.
This frequently includes cannabinoids, which are what give marijuana its euphoric
effects (Leghissa etal. 2018).
To identify and separate the individual compounds present in the plant material,
methods like gas chromatography-mass spectrometry (GC-MS) and thin-layer
chromatography (TLC) are used. To accurately classify the substance under controlled substance laws and assess its potency, this information is crucial.
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16.5.3 Handling andPreserving Evidence
forAccurate Analysis
In forensic drug chemistry, it is crucial to maintain the validity of the evidence. The
accuracy and dependability of analyses can be compromised by improper handling
or storage. To protect the chain of custody and avoid contamination or tampering,
proper protocols must be followed (Sisodia 2022).
Collection Protocols
The reliability of forensic analyses depends on the establishment of standardised collection techniques. This entails using sterile tools, recording the procedure for collecting
samples, and sealing samples in tamper-evident containers. The collection staff must
also receive training to minimise the danger of cross-contamination.
Storage Conditions
In order to maintain the integrity of biological samples and substances, proper storage conditions are essential. Temperature, humidity, and light exposure are just a
few variables that might have an impact on how stable evidence is. To prevent degradation, forensic laboratories need specialised storage facilities with controlled
ambient conditions (Heinsvig etal. 2023a).
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Chain ofCustody
The reliability and admissibility of evidence in court depend on maintaining a clear
and uninterrupted chain of custody. This entails recording each person who touches
the evidence, along with the occasion, duration, and goal of each interaction. A
well-kept chain of custody offers a timeline of the evidence’s progression from collection to analysis.
Critical elements of forensic drug chemistry include an awareness of the various
sample types and the application of appropriate evidence collection techniques.
Forensic chemists can produce precise and trustworthy results by adhering to established procedures and making use of the proper analytical methods, thereby aiding
in the pursuit of justice in drug-related situations (Roux etal. 2022).
A. M. A. Ikbal et al.
16.6 Identication andQuantication
ofRestricted Substances
16.6.1 Principles ofSubstance Identication
An essential component of forensic drug chemistry is the identication of restricted
drugs. It entails a methodical approach that draws on a variety of analytical tools,
reference sources, and professional interpretation (Mercolini and Protti 2016). This
section explores the guiding principles and techniques used throughout the
procedure.
Analytical Techniques
To identify prohibited compounds, forensic chemists use a range of analytical methods.
These methods consist of mass spectrometry, chromatography, and spectroscopy.
• Spectroscopy: This technique examines how matter and electromagnetic waves
interact. Spectroscopy reveals details about the molecular make-up and structure
of substances by examining the absorption or emission of light (Wang etal. 2021).
• Chromatography: Complex mixtures are separated out into their constituent
parts using chromatographic techniques involving gas chromatography (GC) and
high-performance liquid chromatography (HPLC). To isolate particular com-
pounds for additional investigation, this is essential (Strynar etal. 2023).
• Mass spectrometry: By determining the mass-to-charge ratio of ions, mass spec-
trometry enables the measurement of molecular weights and structures. It is very
helpful for verifying the origin of substances (Fisher etal. 2022).
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Reference Materials andLibraries
• Reference resources are essential for identifying substances. These materials are
made up of veried samples with well-known chemical compositions. In order to
compare analytical data from unknown samples with those in reference libraries,
forensic chemists use them as a baseline.
• Spectral Libraries: These databases hold spectra collected from well-known mate-
rials. Forensic chemists can make educated guesses by comparing the spectrum
data of an unknown compound to those in the library (Elkins and Zeller 2021).
• Standard Compounds: These are unadulterated substances with well-known
chemical make-ups. They act as concrete evidence for establishing a substance’s
identity.
Expert Interpretation
Forensic chemists use their knowledge and experience to interpret the ndings of
analytical procedures. This includes taking into account a number of variables, such
as the analytical method utilised, the existence of impurities or adulterants, and any
background information provided by law enforcement (Merone etal. 2021).
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16.6.2 Quantitative Analysis forDetermining
Drug Concentrations
Forensic drug chemistry frequently includes the quantication of drug concentrations in addition to the identication of banned drugs. For both evaluating the potential effects on an individual and for legal actions, this information is essential
(Donati and Amais 2019).
Calibration Curves andStandards
The creation of calibration curves is a prerequisite for quantitative analysis. To
determine a correlation between the recorded signal and the concentration, it is
necessary to examine known concentrations of the chemical. Forensic chemists can
precisely determine the concentration by comparing the signal from an unknown
sample to the calibration curve.
• Internal Standards: These are additives to both the standard solutions and the
unidentied samples that have a known concentration. They aid in adjusting for
differences in sample processing and instrument response (Fares etal. 2022).
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Validation andQuality Control
Forensic laboratories adopt validation processes and quality control measures to
guarantee the accuracy and dependability of quantitative analyses.
• Method validation: This procedure evaluates the analytical method’s perfor-
mance traits. It involves guring out variables like linearity, selectivity, accuracy,
and precision (Gliozzo 2020).
• Quality Control Samples: These are predetermined samples whose composition
is known and which are frequently examined alongside unidentied samples.
They act as controls to make sure the analytical process is operating within rea-
sonable bounds (Lim etal. 2021).
A. M. A. Ikbal et al.
16.6.3 Challenges inDetecting Trace Amounts
Forensic chemists face particular difculties when detecting banned compounds in
tiny levels. Specialised methods and increased sensitivity are necessary in these
circumstances.
Sensitivity ofAnalytical Instruments
For detecting tiny levels, cutting-edge analytical tools with exceptional sensitivity
are necessary. This also applies to sensors with improved signal-to-noise ratios and
lower detection limitations (Sisco and Forbes 2021).
Sample Preparation Techniques
It is possible to concentrate and improve the detectability of trace compounds by
using specialised sample preparation techniques, such as solid-phase extraction and
derivatization.
Quality Assurance Measures
When working with trace levels, rigorous quality assurance procedures are very
important. These procedures include routine instrument calibration and validation.
In conclusion, crucial components of forensic drug chemistry are the quantication
and identication of prohibited drugs. Forensic chemists can deliver precise and trustworthy results by combining analytical methods, reference materials, and professional
interpretation. Additionally, the quantication of drug concentrations adds an essential dimension to the investigation and makes it possible to fully comprehend the
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potential effects on people and legal actions. Despite the difculties presented by trace
quantities, specialised methods and strict quality control procedures enable forensic
chemists to expertly and condently traverse this challenging environment.
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16.7 Evolution ofIllicit Substances
16.7.1 Understanding Designer Drugs
andSynthetic Compounds
With the rapid emergence of new chemicals, the landscape of illegal substances is
always changing. This section explores the idea of designer drugs and synthetic
substances, their history, and the difculties they provide in forensic drug analysis
(Huestis etal. 2017).
Denition andCharacteristics
The term “designer drugs” (sometimes referred to as “novel psychoactive substances” or “NPS”) refers to synthetic substances created to replicate the effects of
prohibited substances. They are frequently produced by altering the chemical composition of already-approved medications, producing in compounds with comparable or even improved pharmacological effects. They are therefore particularly
difcult to recognise and categorise (Jagadeesh etal. 2022).
Origins andMotivations
There are several different aspects that inuence the development of designer medications. These can involve tries to get around current drug restrictions, take advantage of legal weaknesses, or satisfy certain market desires. In order to synthesise
these molecules, underground labs and covert chemists are essential. They use their
chemistry expertise to produce substances with modied structures and qualities
(Nitescu 2019).
Diversity ofDesigner Drugs
Synthetic cathinones (often referred to as “bath salts”), synthetic cannabinoids, and
new hallucinogens are only a few examples of the diverse chemicals that fall under
the category of “designer drugs.” Since each group has a different chemical make up and pharmacological prole, identifying them can be challenging (Musselman
and Hampton 2014).
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