Cocaine and some of its products in hair by RIA and GC/MS

Noncomminuted hair samplings (100 mg) from 132 individuals were analyzed for cocaine products by both RIA and GC/MS with D3 internal standards and selected ions for cocaine, benzoylecgonine, and methylecgonine. Ethanol and pH 7 buffer washing until the washes were negative by RIA or GC/MS were followed by overnight digestion in warm 0.1M HCI. A small portion of digest buffered to pH 7 was analyzed by RIA. The remainder, internally standardized, buffered extract was TMS derivatized and analyzed on a capillary OV-1 column by GC/MS. Of the 132 specimens, 10 were positive by RIA and positive by GC/MS for cocaine only, while another 20 specimens were positive for both cocaine and benzoylecgonine by GC/MS as well as positive by RIA. One specimen that was positive by RIA was positive for cocaine and methylecgonine by GC/MS; an additional one was positive for cocaine, methylecgonine, and benzoylecgonine and positive by RIA. The RIA used (100x more reactive to cocaine than to benzoylecgonine) gave positive test results for an additional 47 of the 132 hair samples. Cutoffs used for the RIA were equivalent to 2 micrograms benzoylecgonine or 0.04 micrograms cocaine/g hair, and for GC/MS, cutoffs per gram hair were 0.1 micrograms cocaine and 0.2 micrograms benzoylecgonine or methylecgonine. Relationships between RIA and GC/MS results and distribution of values found are discussed, as are factors that appear to affect recovery from the hair.