| Drug abuse has become a worldwide epidemic and is correlated to various serious health problems as well as increased rates of crime; thus, detecting and quantifying cocaine in oral fluid is of significant importance for practical forensics. To date, mainly destructive methods or biochemical tests have been used, while spectroscopic methods were only applied to pretreated samples. In this study, the possibility of using Raman spectroscopy to detect cocaine in oral fluid without pretreatment of samples was investigated. It was found that normal Raman spectroscopy at an excitation wavelength of 407 nm produced no cocaine signal while use of Raman spectroscopy at an excitation wavelength of 785 nm only produced a cocaine signal at high cocaine concentrations. Analysis using excitation wavelengths in the ultraviolet range of light (240 nm and 200 nm), however, allowed for the detection of cocaine in oral fluid down to a detection limit of 10 microg/mL without the need for sample pretreatment. |
