ABSTRACT
Techniques for the detection and identification of drugs of abuse in urine are applied in a variety of fields, including sports medicine, forensic science, and for employee and preemployment screening. Limits of detection are therefore higher than those used in preemployment screening. All fields should operate, however, to the same absolute standard of specificity, as the consequences of error can be monitored by performance in an external quality assessment scheme (EQAS). An EQAS for clinical testing for drugs of abuse in urine was established in the United Kingdom in 1987. The specificity of different analytical techniques was studied by calculating its inverse from the results of tests on those samples not containing the analyte in question. The sensitivity of different analytical techniques was studied by calculating its inverse from the results of tests on those samples containing the analyte in question.
