Analysis of Plasma Diethyldithiocarbamate–A Metabolite of Disulfiram

Abstract

A reversed-phase high-performance liquid chromatographic analysis was developed for diethyldithiocarbamate in plasma. Following treatment of plasma (1 ml) with methyl iodide (250 μl), biphenyl (internal standard, 1.8 μg) was added in chloroform (6 ml). After shaking (30 min.), the chloroform was separated and evaporated under nitrogen (to 50 μl). Acetonitrile (250 μl) was added and the solution was again evaporated under nitrogen (to 100 μl). Aliquots (25 μl) were chromatographed using acetonitrile: acetate buffer (65:35, pH 4) at 2.5 ml/min on a 5 micron C-8 column with detection at 276 nm. Recovery of methyldiethyldithiocarbamate (MeDDC) was 92.5 ± 3.2%. Retention times and theoretical plates for MeDDC and biphenyl were 3.0 and 4.6 min., and 4660 and 6336 respectively. The analysis was linear over the range 25 to 400 ng/ml with a coefficient of variation of 3.2%. Analysis of samples after intravenous disulfiram (10 mg) administration to rats yielded a total body clearance of 343 ml/min. This supports the view that metabolism is principally by extra-hepatic routes.