title: Mass screening and confirmation of barbiturates in urine by RIA/gas chromatography.
abstract: A rapid, sensitive and specific procedure is described for the mass screening and confirmation of barbiturates in urine specimens. The method is sensitive to 0.5 mug/ml levels of the commonly used barbiturates. The urine samples are screened by radioimmuno-assay. Specimens  screened positive are confirmed by gas-liquid chromatography using a flame ionization detector. The barbiturates are analyzed as free acids on a 10% UC W-98 column and as their dimethyl derivatives on a 3% OV-17 column. This dual approach eliminates false positives caused by interfering substances which may be present in the urine, thus resulting in a method specific for the barbiturates.
mesh_terms: D001463:Barbiturates / Q000652:urine*; D002849:Chromatography, Gas; D006801:Humans; D008403:Mass Screening; D008722:Methods; D011863:Radioimmunoassay
chemical_list: D001463:Barbiturates