Determination of p-methylthiobenzamide and p-methylthiobenzamide-S-oxide from rat plasma using solid-phase extraction and high-performance liquid chromatography.
p-Methylthiobenzamide (PMTB) is a thiocarbonyl compound exhibiting marked hepatotoxicity and nephrotoxicity. We describe a high-performance liquid chromatographic method for analyzing PMTB and a metabolite, p-methylthiobenzamide-S-oxide (PMTBSO), from rat plasma using a solid-phase extraction technique. In this way, PMTB and PMTBSO can be extracted from 0.5 ml of plasma and separation achieved by an ODS analytical column in as little as 9 min. The mobile phase used was methanol-water (55:45, v/v) and the wavelength for detection was 290 nm. The limits of detection in plasma were 15 ng/ml for PMTB and 33 ng/ml for PMTBSO; the absolute recovery from spiked plasma samples was greater than 84.4% for both compounds and the internal standard. The method was linear throughout the range used with correlation coefficients greater than 0.969. The intra-day accuracy ranged from 1.52 to 15.23% relative error for the PMTB concentration range 151-3025 ng/ml; accuracy of 4.97% or less was obtained for PMTBSO concentrations of 1672-20,068 ng/ml. The intra-day precision (coefficient of variation) of the procedure was found to be no greater than 5.28% for PMTB and 7.9% for PMTBSO. Inter-day accuracy and precision measurements were similar.
Davidson
V P
VP
Department of Pharmacology and Toxicology, University of Kansas, School of Pharmacy, Lawrence 66045-2500.
Traiger
G J
GJ
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013056:Spectrophotometry, Ultraviolet; D013854:Thioamides / Q000097:blood*
D013854:Thioamides; C071096:4-methylthiobenzamide; C071098:4-methylthiobenzamide-S-oxide; C015539:thiobenzamide