Metabolism of C-labelled and non-labelled sulfadiazine after administration to pigs

• Published in: Analytical and bioanalytical chemistry 2007-08, Vol.388 (8), p.1733-1745
• Main Authors: Lamshoft, Marc, Sukul, Premasis, Zuhlke, Sebastian, Spiteller, Michael
• Format: Article
• Language: English
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-007-1368-y

The behaviour of sulfadiazine (SDZ) and its metabolites was investigated by administering the C-labelled veterinary drug to fattening pigs. The excretion kinetics were determined after daily collection of manure. Two known metabolites, N-acetylsulfadiazine and 4-hydroxysulfadiazine, and two hitherto unidentified minor metabolites were recovered. Various mass spectrometric techniques such as parent, product ion scans and accurate mass measurement were used. The new compounds were identified as N-formylsulfadiazine (For-SDZ) and N-acetyl-4-hydroxysulfadiazine (Ac-4-OH-SDZ). The identification of SDZ, Ac-SDZ and For-SDZ was confirmed by comparison of the spectroscopic and chromatographic data of the synthesized authentic references. The identification of the hydroxylated compounds 4-OH-SDZ and Ac-4-OH-SDZ was performed by MS, and accurate mass measurements. Only 4% of the administered radioactivity remained in the pig after ten days and SDZ accounted for 44% of the 96% radioactivity excreted. More than 93% of the labelled compounds were detected and identified in the manure. The key analytical problem, namely a high concentration of matrix in sample extracts, was overcome by advanced measurement techniques and with the use of a suitable internal standard. The mean recoveries for all compounds were > =96%. Linearity was established over a concentration range of 0.5 to 10,000 mug kg manure with a correlation coefficient > =0.99. The same experiment was carried out simultaneously with non-labelled SDZ to obtain manure for outdoor soil experiments.