COMPARISON OF 3 ANALYTICAL METHODS FOR COCAINE ANALYSIS OF ILLICIT POWDERS

A new cocaine-sensitive ISFET device based on a cocaine-reineckate ion -pair complex dispersed in a PVC-sebacate matrix has been fabricated. This sensor displays a linear range for cocaine hydrochloride between about 3 x 10(-6) and 2 x 10(-2) M and a fast response (less than or eq ual to 25 s), which remains almost constant over the pH range 3-7. The sensor has been applied to the analysis of authentic illicit powders containing cocaine hydrochloride and other substances commonly associa ted with it, or of cocaine free base (crack). Experimental results wer e compared with those obtained employing two more common instrumental methods of analysis: gas chromatography (GC), and UV absorption spectr ometry (the latter applied directly or based on second derivative abso rption spectroscopy). Good agreement was found between results obtaine d by ISFET and GC methods, while UV absorption spectrophotometry prove d suitable only in the case of pure cocaine hydrochloride and free bas e, or in samples also containing lidocaine, but using second derivativ e absorption spectroscopy.