Raman Spectroscopy Takes a Leap Forward in Forensic Drug Detection

In a recent study published in the journal Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, a collaborative research team, comprised of researchers from the University at Albany, SUNY, Elettra Sincrotrone Trieste, and Kuwait University, explored a new method that can improve detection of antihistamines in oral fluid samples. The findings of this study reveal that this novel method, deep ultraviolet Raman spectroscopy (DUVRS), has potential in being applied in cases involving drug overdoses, substance abuse, and trafficking (1).

Drug overdoses are unfortunately becoming more prevalent in American society. Since 1990, the number of fatalities by drug overdoses has increased substantially. In 2022, there was a reported 107,941 drug overdose deaths in the United States (2). However, what has changed is the type of illicit drugs that are causing these deaths. Back in 1990, prescription opioids were the leading cause of drug overdose deaths, but this number has decreased in recent years. In 2022, synthetic opioids, primarily fentanyl, were the leading cause of drug overdose deaths, claiming a reported 73,838 lives (2). Psychostimulants, such as methamphetamine, and cocaine round out the top three most lethal drugs (2).

Some scattered pills on table. Generated using AI. | Image Credit: © Rafa Fernandez - stock.adobe.com

Determining the type of drug found in cadavers’ bodies, as well in any oral fluid sample, is important, because it could help influence and dictate policy prescriptions. Both politicians and pharmacists rely on this information to try and make sure that only drugs designed to cure a specific ailment or condition are allowed on the market, and that any harmful substance is banned.

In this study, the research team demonstrated the potential of deep ultraviolet Raman spectroscopy (DUVRS) as a nondestructive, sensitive tool for detecting antihistamines in oral fluid samples (1). Antihistamines are medicines used often to relieve allergy symptoms, such as hay fever (3). They are generally grouped into two categories: those that make you feel sleepy, and those considered non-drowsy antihistamines (3).

This study focused on the detection of cetirizine (CTZ), a non-drowsy antihistamine, in both liquid and dried oral fluid samples (1,3). Oral fluid, often referred to as oral saliva, is an accessible and less invasive sample matrix that plays a growing role in forensic science (1). Although traditional methods for detecting drugs in biological fluids involve extensive sample preparation, DUVRS eliminates this need, offering simplicity, speed, and precision (1).

The research team utilized DUVRS with laser excitation at 213 nm to achieve a limit of detection (LOD) for CTZ at 50 µg/mL in liquid oral fluid samples (1). Additionally, they successfully analyzed dried oral fluid stains doped with CTZ, replicating forensic scenarios where bodily fluid stains are found at crime scenes (1). By integrating multivariate statistical analysis with DUVRS, they could confidently differentiate between pure oral fluid samples and those contaminated with CTZ (1).

Because DUVRS is nondestructive, the samples are not destroyed during analysis, which is optimal when conducting forensic analysis. Ultimately, this allows forensic scientists to conduct further analysis of the sample if needed (1). DUVRS also can be performed quickly, which makes it good to use for time-sensitive situations, which is often the case in criminal investigations (1).

Although the findings are encouraging for DUVRS usage in forensic investigations more broadly, the researchers acknowledge the need for further development to make this method practical for routine forensic use (1). First, the authors discuss limitations with their sample size. To ensure DUVRS is effective on a wide-scale basis, expanding the scope of the study to include a more diverse cohort of donors and a wider range of drugs is essential (1).

Additionally, the sensitivity of DUVRS for CTZ detection is currently lower than some traditional methods. Addressing this limitation while maintaining the simplicity and nondestructive nature of the approach will be key to its adoption in forensic laboratories (1).

Overall, this is a proof-of-concept study that suggests technological advancements in Raman spectroscopy may result in its broad applicability in forensic analysis. The researchers’ ability to detect antihistamines in both liquid and dried oral fluid samples highlights the versatility of DUVRS, and its rapid, nondestructive analysis capabilities align with the increasing demand for efficient and accurate forensic techniques (1).

References

1. Amin, M. O.; Matroodi, F.; Al-Hetlani, E.; Rossi, B.; Lednev, I. K. Deep Ultraviolet Raman Spectroscopic Analysis of Antihistamine Drugs in Oral Fluid for Forensic Purposes. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2025, 329, 125595. DOI: 10.1016/j.saa.2024.125595
2. National Institute on Drug Abuse, Drug Overdose Deaths: Facts and Figures. NIH.gov. Available at: https://nida.nih.gov/research-topics/trends-statistics/overdose-death-rates#Fig1 (accessed 2025-01-27).
3. National Health Service, Antihistamines. NHS.uk. Available at: https://www.nhs.uk/conditions/antihistamines/#:~:text=Antihistamines%20are%20medicines%20often%20used,are%20only%20available%20on%20prescription. (accessed 2025-01-28).