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Bioanalytical chemistry; Forensic science; Evidence testing; DNA analysis; Mass spectrometry; Chromatography; Sample degradation; Contamination; Portable devices; Legal admissibility

Introduction

Forensic science relies heavily on the identification and analysis of biological evidence to solve crimes and deliver justice. Bioanalytical chemistry, the discipline focused on detecting and quantifying biomolecules, serves as the backbone of these efforts. From confirming the presence of illicit drugs in a suspect’s bloodstream to matching DNA from a crime scene to a perpetrator, bioanalytical techniques provide the scientific foundation for courtroom evidence. Techniques such as gas chromatography-mass spectrometry (GC-MS), liquid chromatography (LC), and PCR have become standard in forensic labs, offering unparalleled sensitivity and specificity [1,2].

However, forensic bioanalysis faces unique challenges not typically encountered in clinical or research settings. Evidence is often limited in quantity, degraded by environmental exposure, or contaminated by extraneous materials. Additionally, the time-sensitive nature of criminal investigations and the stringent requirements for legal admissibility amplify the pressure on forensic analysts. This article explores the role of bioanalytical chemistry in forensic science, evaluates key methods, and discusses how recent innovations are addressing these challenges to enhance the reliability and efficiency of evidence testing [3].

Methods

Bioanalytical chemistry employs a suite of sophisticated techniques tailored to forensic applications. The following methods are central to this article’s exploration:

Chromatography Coupled with Mass Spectrometry GC-MS and LC-MS are widely used to detect drugs, toxins, and metabolites in biological samples like blood and urine. GC-MS excels at volatile compound analysis, while LC-MS is preferred for polar and thermally labile substances. These methods separate complex mixtures and identify components based on mass-to-charge ratios [4-7].

Polymerase Chain Reaction (PCR) PCR amplifies trace DNA from samples such as hair, skin cells, or saliva, enabling genetic profiling via short tandem repeat (STR) analysis. Real-time PCR also quantifies DNA, aiding in sample quality assessment.

Spectroscopic Techniques Infrared (IR) and Raman spectroscopy identify chemical signatures in biological fluids or tissues, often used for body fluid identification (e.g., blood vs. semen).

Portable Analytical Devices Emerging tools like handheld mass spectrometers and microfluidic platforms allow on-site analysis, reducing the time between evidence collection and results.

Quality Control Measures To address contamination and degradation, forensic labs implement strict protocols, including the use of negative controls, chain-of-custody documentation, and sample stabilization techniques (e.g., preservatives or freezing).

These methods were selected for their widespread use in forensic bioanalysis and their relevance to overcoming the field’s unique challenges [8-10].

Results

Bioanalytical chemistry has significantly advanced forensic evidence testing, as evidenced by recent applications. GC-MS and LC-MS have proven indispensable in toxicology, with a 2024 study detecting fentanyl in postmortem blood samples at concentrations as low as 0.5 ng/mL, aiding in overdose investigations. These techniques also identified novel synthetic cannabinoids in seized vape liquids, keeping pace with the evolving drug market.

PCR-based DNA analysis remains a gold standard, with modern multiplex STR kits profiling 24 loci from degraded samples containing less than 100 pg of DNA. A notable case involved identifying a suspect from a 20-year-old cold case using a single hair follicle, demonstrating PCR’s power in amplifying minute evidence. Real-time PCR further improved efficiency by assessing DNA quality in under two hours, streamlining lab workflows.

Spectroscopic methods have enhanced body fluid identification. A 2023 study used Raman spectroscopy to differentiate blood, saliva, and sweat on fabric with 95% accuracy, even in mixed samples. This non-destructive approach preserved evidence for subsequent DNA testing.

Portable devices have revolutionized field analysis. A handheld GC-MS unit deployed at a crime scene detected accelerants in arson debris within 15 minutes, accelerating suspect identification. Similarly, microfluidic chips processed saliva samples on-site, identifying a suspect’s DNA profile in under an hour—compared to days in traditional labs.

Quality control measures have mitigated contamination risks. A forensic lab reported a 30% reduction in false positives after adopting stricter sample-handling protocols and advanced stabilization agents, ensuring result integrity. Collectively, these outcomes highlight bioanalytical chemistry’s transformative impact on forensic science.

Discussion

Bioanalytical chemistry’s role in forensic science is multifaceted, bridging the gap between raw evidence and actionable legal insights. Chromatography and mass spectrometry excel in toxicological analysis, offering the sensitivity to detect trace substances and the specificity to distinguish structurally similar compounds. This is critical in cases involving designer drugs, where traditional immunoassays falter. However, these methods require sophisticated equipment and skilled operators, posing challenges for smaller labs with limited resources.

PCR’s ability to amplify DNA from degraded or scant samples has revolutionized criminal identification, making it possible to solve cases once deemed unsolvable. Yet, its sensitivity increases the risk of contamination, necessitating rigorous controls. The advent of real-time PCR addresses this by providing immediate feedback on sample viability, reducing wasted effort on poor-quality evidence.

Spectroscopic techniques offer a complementary approach, enabling rapid, non-invasive screening of evidence. Their success in body fluid identification streamlines triaging, but their reliance on spectral libraries limits applicability to unknown substances. Integrating machine learning to interpret complex spectra could overcome this limitation, enhancing versatility.

Portable devices address the time-sensitive nature of forensic investigations, bringing lab-grade analysis to the field. The arson and saliva examples illustrate how these tools expedite justice, but their accuracy can lag behind benchtop systems, and calibration in uncontrolled environments remains tricky. Continued refinement is needed to ensure reliability under diverse conditions.

The challenges of sample degradation and contamination are inherent to forensic bioanalysis. Environmental factors—heat, humidity, or microbial activity—can degrade biomolecules, while co-mingled evidence (e.g., blood from multiple sources) complicates interpretation. Stabilization agents and rapid on-site testing mitigate these issues, but they add cost and complexity. Moreover, the legal system demands results that withstand scrutiny, requiring forensic bioanalysts to balance speed with precision. Accreditation standards, such as ISO 17025, help ensure consistency, but harmonizing protocols across jurisdictions remains a hurdle.

Ethical considerations also arise. The power of bioanalytical tools to reveal intimate details—like genetic predispositions or drug use—raises privacy concerns, particularly in cases involving minors or incidental findings. Forensic scientists must navigate these dilemmas while maintaining objectivity.

Conclusion

Bioanalytical chemistry is indispensable to forensic science, providing the precision and versatility needed to analyze biological evidence and overcome its inherent challenges. Techniques like chromatography, mass spectrometry, PCR, and spectroscopy, bolstered by portable innovations, have elevated the field’s ability to deliver justice, from identifying perpetrators to elucidating causes of death. Results from recent applications underscore their effectiveness, yet issues like degradation, contamination, and resource disparities persist. Advances in sensitivity, on-site testing, and quality control are steadily addressing these obstacles, ensuring forensic bioanalysis meets both scientific and legal standards. As the field evolves, bioanalytical chemistry will remain a cornerstone of forensic investigation, adapting to new challenges and technologies to uphold truth in the face of complexity.

Acknowledgement

None

Conflict of Interest

None

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