The Evolution of Toxicological Screening Methods In Forensic Science
1. HISTORICAL
OVERVIEW:
Several
analytical techniques are used for Toxicological screening methods which help
in detecting and quantifying toxins.
A
few Early screening techniques used were:
1.
Colour Tests: Specific chemicals react with substances producing
colours.
2.
Microscopy: Detailed examination of tissues or fluids.
3.
Spectroscopy: Identifying and quantifying unknown substances.
4.
Flame Tests: Identifying metal ions based on the colour of flame.
Limitations
faced in the early devices:
1. They lacked sensitivity and specificity
making it difficult to detect substances at low concentrations.
2.
Only qualitative results were provided, quantifying a substance was difficult.
3.
Standardized protocols and procedures did not exist making comparison of
results difficult.
4.
They were susceptible to environmental conditions and portability.
2. ADVANCEMENTS IN
ANALYTICAL TECHNIQUES:
Analytical
methods used in toxicological screening have increased efficiency of drug
detection in biological samples. Instruments which have helped in this are:
1.
GAS CHROMATOGRAPHY:
•
Used to separate, quantity and analyse volatile compounds. Interaction of
stationary phase with sample injected in column separates the components in
sample.
•
The development of capillary columns has enhanced its efficiency.
2.
MASS SPECTROMETRY:
•
Enables detection and provides detailed molecular information of toxins, drugs
and metabolites. Its sensitivity allows identification of substances in trace
levels.
•
Hybrid instrument like Tandem MS enhances specificity, distinguishing similar
substances.
3.
LIQUID CHROMATOGRAPHY:
•
Developments made in stationary phase led to higher separation efficiency.
Advanced column materials and detectors used in modern LC enhances resolution
and sensitivity.
•Coupling
of UPLC (Ultra-Performance Liquid Chromatography) and mass spectrometry leads
to precise separation of compounds.
3. EMERGENCE OF
IMMUNOASSAYS:
•
Introduction of immunoassays have enabled rapid and cost-effective
screening for drugs and toxins. This has transformed the field of forensic
toxicology.
•
They have simple procedures and don't require skilled personnel for
operation giving quick analytical results.
•
They combine speed, efficiency in detecting unknown substances which is
necessary in screening. Thus, immunoassays enhance the scope and efficiency
of forensic analysis.
•
Immunoassays are highly economical and swift option in the field of
forensic toxicology.
4. MINIATURIZATION AND
PORTABLE DEVICE:
•The
field work in forensic toxicology has developed greatly due to introduction of
portable miniaturised devices.
•Miniaturization
allows rapid screening anywhere with increased mobility making
fieldwork more agile.
•They
help in on-site testing, reducing need for sample transportation to
labs.
•
Portable devices can run on battery and easily operable. They help in
efficient analysis of samples at crime scene.
E.g.-
1. Handheld Raman Spectrometers: Detect
unknown substances on field rapidly by producing unique spectral fingerprints
for every substance.
2.
Mobile Breathalyzer Devices: Used for on-the-spot alcohol testing. It
measures blood alcohol concentration from a breath sample of an individual.
5. CHALLENGES AND
LIMITATIONS:
1.
Detection of New Psychoactive Substances (NPS) is challenging since new
illicit substances emerge everyday making identification difficult.
2.
False positives or negatives produced by structurally similar products
or cross reactivity affects the reliability of toxicological results.
3.
Evidences like blood or urine may contain complex
matrices which interrupts substance detection.
4.
Medications or therapeutic drugs may interfere with screening, affecting
results.
5.
Installing new screening methods is expensive. Some methods need
specially trained people to operate them.
6. FUTURE TRENDS AND
DEVELOPMENTS:
1.
Integration of Artificial Intelligence (AI) for Data Analysis: AI
algorithms improve efficiency by analysing vast datasets in seconds which
allows quicker and accurate identification of toxins enhancing the reliability
of Toxicological results.
2.
Rapid and Accurate Point-of-Care Testing: detection of multiple
substances simultaneously and rapidly by on-spot miniaturised, accurate
screening devices allow efficient point of care testing.
3.
Microfluidics and Lab-on-a-Chip Technologies: Microfluidic devices allow
rapid sample processing by automation. They provide simultaneous analysis of
multiple samples with minimal volumes which reduces cost and saves time.
These
advancements could reshape forensic practices, making toxicological analyses
more efficient, accessible and reliable.
7. FORENSIC APPLICATIONS
AND REGULATORY IMPACT:
Forensic
applications of toxicological screening are:
1.
Analysing biological samples from deceased in postmortem investigations
to establish the cause of death.
2.
Helps to identify and quantify the concentration of illicit substances
or alcohol in biological samples in crimes involving drugs.
3.
Analysing biological samples in cases involving poisoning, assault helps to identify
toxins or substances used.
4.
Analysis of Urine and blood samples of athletes to identify the presence
of performance enhancing drugs.
Toxicological
screening used in the field of forensics benefits the legal system, public
safety, and ethical standards.
Forensic
regulations and standards have been influenced by the evolution of
toxicological screening methods:
1.
Emphasis on standardizing procedures have increased. New protocols are
prescribed for sample collection, storage, and analysis. This helps to ensure
consistency across labs.
2.
Cutoff values have been made due to the evolution of screening methods.
They are threshold values used to determine the presence or absence of
substances.
3.
Quality control measures to test the precision, accuracy and reliability
of new screening methods before implementation is ensured.
4.
An increase in ethical considerations and privacy protection has been
noticed. These regulations aim to safeguard individual rights.
8. CASE STUDIES:
1.
George Floyd (2020): GC-MS played an important role in detecting
the presence and concentration of fentanyl and methamphetamine in his body as
presented in the reports.
2.
Whitney Houston (2012): GC-MS was used to detect the levels of
cocaine, benzothiazines and other prescription
medicines in her body. The complexities of substance abuse were highlighted
through this case.
3.
The Jeffrey MacDonald case (1979): was an A.U.S. army officer. He
was accused of murdering his wife and children. Methods like GC, TLC helped
analyse the biological samples and establish cause of death which provided
valuable evidence in this case.
9. CONCLUSION:
•
The evolution of new screening methods like gas chromatography, mass
spectrometry throughout the ages have helped in toxicological screening
providing increased levels of sensitivity and specificity.
•
These developments highlight the ongoing progress in analytical approaches for
better substance detection and identification.
10. REFERENCES:
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2745311/
- https://www.elsevier.es/en-revista-spanish-journal-legal-medicine-446-articulo-the-improvements-in-forensic-toxicology-S2445424923000134
- https://onlinelibrary.wiley.com/doi/abs/10.1002/9780470027318.a1109
- https://www.ncbi.nlm.nih.gov/books/NBK499901/
- https://medcraveonline.com/FRCIJ/forensic-toxicology-biological-sampling-and-use-of-different-analytical-techniques.html
- https://www.hindawi.com/journals/jamc/2018/4142527/
- https://www.slideshare.net/PhYasmin/immunoassay-test-and-forensic-toxicology
- https://www.reuters.com/article/idUSL1N3241XJ/
- https://www.cbsnews.com/news/whitney-houstons-autopsy-how-can-drowning-cocaine-and-heart-disease-all-be-blamed/
- https://www.ukessays.com/essays/sciences/analysis-of-the-investigation-of-the-jeffery-macdonald-murder-case.php
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