Evaluating the detection of cocaine and its impurities concealed inside fruit- and vegetable- food products using handheld spatially offset Raman spectroscopy

Abstract

This study investigated the use of handheld spatially offset Raman spectroscopy for the identification of drugs concealed within fruit and vegetable food products, which is a common method of drug trafficking in busy environments such as airports. Handheld Raman spectroscopy is advantageous due to its mobility, speed, and chemical specificity for drug analysis. In this study, spatially offset Raman spectra of six substances were collected and included cocaine and its impurities. Raman spectra were collected for drugs on their own and for drugs concealed in transparent bags and in various food products such as green pepper, pomegranate, potato, and zucchini. The collected spectra were analyzed using different algorithms. The results showed successful identification of drugs in three out of the four tested food products, except for pomegranate, which had a thick rind and spongy tissue that hindered detection. An instrumental hit quality index algorithm provided instant identification with matches above 80% in the three identified products. Correlation in wavelength space yielded high correlation coefficient values between substances in food substrates and reference substances, although there were a few false negatives due to noisy spectra. Principal component analysis successfully differentiated between drugs in different food products. In summary, the study demonstrated the potential of handheld spatially offset Raman spectroscopy for identifying drugs concealed within food products. Future work aims to expand the technique to a wider range of substances and food products and develop a quantitative approach to predict substances’ concentrations. Overall, this research contributes to the field of forensic applications and offers insights into the detection of illicit drugs in challenging scenarios.