Development of a new field-test procedure for cocaine

The Scott test, widely used as the field test for cocaine, is performed in three steps. If a sample contains cocaine, blue precipitates appear in step 1, the precipitates are dissolved and the solution turns pink in step 2, and the lower layer turns blue in step 3. However, some pyrrolidine-type cathinones produce cocaine-like results when tested, necessitating modification of the test procedure. Filtration of the second-step mixture weakened the blue color in step 3; however, the blue color did not completely disappear. Adding the Chen-Kao reagent to the test procedure enhanced the differentiation: when the reagent was added to cocaine, the solution was initially turbid, but then became clear over time; its addition to cathinones resulted in turquoise or light sky-blue precipitation. These results indicated that the Chen-Kao test was useful for exclusion of cathinones. A combination of the modified Scott test and the Chen-Kao test was successfully applied to the forensic samples containing cocaine or pyrrolidine-type cathinones. In conclusion, a combination of these tests will be the useful field-test procedure for cocaine.