Raman Spectroscopic Examination of Six Drug Seizures at Different Excitation Wavelengths

In this article, the Raman spectrum inspection performance of six drug seizures at three different excitation wavelengths (532, 785, and 1064 nm) is compared using Raman spectroscopy. Three to five distinctive scattering peaks in the Raman fingerprint area (100–1800 cm^-1), with greater scattering intensity and no interference from typical adulterants, were chosen as the bass for the qualitative matching of the drug seizures when compared to the Raman spectra of the drug standards. It was discovered that in order to perform a Raman investigation of drug seizures, appropriate excitation wavelengths must be chosen based on the kind of drug involved. Additionally, if the drug seizures contain adulterated substances, the distinctive peaks of the pharmaceuticals that escape adulteration should be chosen for comparison. For seized heroin (HER), caffeine (CAF) and 3,4-methylenedioxymethamphetamine (MDMA), the near-infrared (NIR) excitation wavelengths of 785 nm and 1064 nm are better than that of 532 nm for the Raman test, in which the 1064 nm significantly reduces the background fluorescence of the HER seizure; for seized methamphetamine (MAMP) and ketamine (KET), the effect of the change of excitation wavelength was small, and the Raman response was good at three different excitation wavelengths, and the relative intensities of the Raman peaks in the fingerprint region and the functional group region (2500 to 3200 cm^-1) showed regular changes; for the Raman analysis of Magu, the excitation wavelength of 785 nm was superior, with a higher spatial resolution, which could observe more characteristic peak information while avoiding the fluorescence effect. This research work is based on Raman spectroscopy, which will provide a strong reference and basis for drug enforcement.