Disappearance of cocaine from human hair after abstinence.

In this work the study of the disappearance of cocaine in hair is reported. The subject of the study is a woman who stopped the consumption of cocaine after a period of drug abuse of over 1 year. Hair samples were collected over a period of 10 months. During this time the absence of cocaine intake was monitored by the toxicological analysis of urine, performed every 2 days. After decontamination with methanol, the hair sample, cut in two segments (0-1.5 and 1.5-3 cm from the hair root) was added with cocaine-D(3) (internal standard), hydrolyzed and extracted with chloroform/isopropanol (9:1). The extract was evaporated to dryness, reconstituted in 25 microl of ethyl acetate and analyzed by GC-MS in SIM mode. The obtained results show that the incorporation of cocaine in hair decreased during the first 3 months after the last consumption and after this period of time no cocaine was found in the hair sections closest to the root.