Confirmation of the Presence of Drugs of Abuse in Urine

Urine screenings for drugs of abuse are performed for many reasons, two of the most common being workplace/employment screening and monitoring in drug-dependence treatment centers. In both, the initial screen is commonly an immunoassay. Negative results require no further action. Positive tests require a second different method to both confirm and identify which drug is present. Some perfectly legal preparations crossreact with immunoassays. Employment screening has more stringent requirements than does monitoring of known drug abusers (1 ), and gas chromatography–mass spectrometry (GC–MS) (2 ,3 ) is the method of choice. For the monitoring of known drug abusers attending drug-dependence centers, less sophisticated methods, such as thin layer chromatograghy (TLC) (4 ) and high-performance liquid chromatography (HPLC) (5 ,6 ), are frequently used. Capillary electrophoresis (CE) methods have been described for the detection of drugs of abuse in pharmacological/illicit street samples (7 –9 ), and a few methods have been published using biological materials (10 –12 ). This chapter describes a simple sample preparation method, followed by CE for the confirmation and identification in urine of opiates, methadone (and its main metabolite EDDP), and amphetamines. Samples are prepared by a solid phase extraction procedure using columns packed with a co-polymeric material. This is a silica-based material to which is bound a mixture of hydrophobic and ionic groups.