Semi-quantitative analysis of drugs of abuse, including tetrahydrocannabinol in hair using aqueous extraction and immunoassay

A semi-quantitative analytical screening procedure for the determination of cocaine, amphetamines, opiates, and delta-9-tetrahydrocannabinol in hair has been developed. The procedure employs an aqueous extraction buffer, uses only 10 mg of hair, requires 2 h of incubation for the extraction to occur, and multiple drug classes can be screened using enzyme linked immunosorbent assays. Hair calibration standards were prepared around the recommended cut-off concentrations of the Society of Hair Testing. All drug classes showed excellent linearity over the concentration range tested, indicating that immunochemical screening can be used in a semi-quantitative mode for hair analysis using an aqueous buffer, rapid extraction and a small amount of hair.