A New Approach to Drug Testing: Electrochemical Sensors and Raman Spectroscopy
by Jo Ellen Knott
Forensic laboratories screen for drugs using a combination of presumptive and confirmatory tests. The presumptive test indicates the presence or absence of a drug and is usually done in the field by law enforcement using colorimetric tests. The confirmatory testing is usually done in a lab using spectroscopy methods.
While colorimetric tests are quick and inexpensive, they are limited by their non-specificity and can often lead to inconclusive results. To address these limitations, researchers at West Virginia University, funded by the National Institute of Justice, have been exploring the use of electrochemical techniques and Raman spectroscopy for drug detection and identification.
Dr. Luis Arroyo and his team worked on using electrochemical sensors to detect emerging drugs like fentanyl and new psychoactive substances. These sensors, commonly used in various fields, such as biomedicine and environmental sciences, measure electrical conductivity to identify the presence of a drug. Arroyo and his researchers are using screen-printed carbon electrodes, a type of electrochemical measurement device manufactured by printing carbon ink onto a plastic or ceramic substrate using a screen-printing process. This technique allows for rapid and reproducible production of disposable electrodes with small sizes and low costs.
The researchers also employed Raman spectroscopy, a non-destructive technique that analyzes the structural fingerprint of a substance, to confirm their findings. Raman spectroscopy measures relative frequencies at which a sample scatters radiation, unlike infrared spectroscopy which measures absolute frequencies at which a sample absorbs radiation. The researchers tested the usefulness of portable Raman spectroscopy for drug identification outside of the lab.
By combining these two methods, the research team at West Virginia University achieved an overall identification accuracy of 87.5% for fentanyl and its analogs, a significant improvement over traditional color tests. The researchers commend the advantages of these techniques, including their versatility, selectivity, sensitivity, minimal sample preparation, speed, low cost, robustness, and portability.
The real value of this approach lies in the additional information it provides to forensic scientists. For example, the ability to identify fentanyl in complex mixtures and distinguish between different fentanyl analogs is a significant advancement. While many forensic laboratories still rely on color tests, this research demonstrates the potential of electrochemical sensors and Raman spectroscopy to improve drug testing procedures.
Currently these methods are not yet used in forensic drug testing on a broad basis. However, Dr. Arroyo believes his research can pave the way for their implementation.
Source: Forensic
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