Sensing cocaine in saliva with infrared laser spectroscopy

Increasing numbers of accidents caused by drivers under the influence of drugs, raise drug tests to worldwide interest. We developed a one-step extraction technique for cocaine in saliva and analyzed reference samples with laser spectroscopy employing two different schemes. The first is based on attenuated total reflection (ATR), which is applied to dried samples. The second scheme uses transmission measurements for the analysis of liquid samples. ATR spectroscopy achieved a limit of detection (LOD) of 3 mu g/ml. The LOD for the transmission approach in liquid samples is < 10 mu g/ml. These LODs are realistic as such concentration ranges are encountered in the saliva of drug users after the administration of a single dose of cocaine. An improved stabilization of the set-up should lower the limit of detection significantly.