A rapid horizontal TLC method for detecting drugs of abuse

We present a rapid, low-cost method for detecting opioids, cocaine and amphetamine in the urine of drug abusers. Rapid solid phase extraction of 2 mL of urine using octadecylsilane cartridges (Bond Elut C18) concentrates compounds of interest (including the polar metabolite of cocaine, benzoylecgonine), in a small volume of methanol, which is easily dried down. Four microlitres of aliquots of samples and standards are spotted on to 5 cm square polyester-backed silica gel plates, and developed (8-10 min) in a Desaga H-Chamber. Rf values of all relevant compounds are presented for two mobile phases using an iodoplatinate spray. The sensitivity of the method is not the same for all drugs but is always at least 1 microgram/mL urine. A number of investigations can be performed on a single extract from 2 mL of urine including confirmatory tests using different solvent systems or sprays.