Evaluation of Shifted-Excitation Raman Difference Spectroscopy and Comparison to Ordinary Portable Raman Spectroscopy in Identification of Seized Drugs

Abstract

Rapid and accurate identification and detection of illicit drugs are important for combating drug crimes. As a newly developed technology, shifted-excitation Raman difference spectroscopy (SERDS) can greatly reduce the interference caused by fluorescence and improve the potential of Raman for distinguishing drug compounds in seized samples with fluorescent additives. In this work, 43 random seized drugs were scanned and analyzed by both SERDS and ordinary portable Raman spectrometers for the first time. The detected results of two Raman technologies were confirmed with gas chromatographic mass spectrometry test results, and compared in detail in the aspects of detection rate and matching accuracy. SERDS had significant advantages in eliminating fluorescence interference with a very high detection rate of 93.0%, compared with 53.3% obtained by an ordinary Raman spectrometer, although the ordinary Raman spectrometer analyzed the composition of multi-component mixed samples with higher accuracy. To some extent, the two Raman spectrometers realized functional complementarity, and a rational use of the two types of Raman spectrometers may be of benefit in the rapid detection of seized drugs.