Comparative analytical quantitation of clenbuterol in biological matrices using GC-MS and EIA

A simple and sensitive procedure utilizing CC-MS for the identification and quantitation of clenbuterol in biofluids and tissues is described. This im proved method utilizes trimethylboroxine for the derivatization of clenbute rol, requires only 1 mL/g of biological sample, and most importantly does n ot require an extra cleaning step for urine specimens prior to extraction. Linear quantitative response curves have been generated for derivatized cle nbuterol over a concentration range of 5-200 ng/mL. The extraction efficien cy at four representative points of the standard curve exceeded 90% in both specimen types (plasma and urine). Linear regression analyses of the stand ard curve in both specimen types exhibited correlation coefficients ranging from 0.997 to 1.000. The Limit of detection (LOD) and Limit of quantitatio n (LOQ) values for plasma specimens were determined to be 0.5 and 1.5 ng/mL respectively. For urine specimens, LOD and LOQ values were 0.2 and 0.7 ng/ mu L respectively. Percentage recoveries ranged from 91 to 95% for urine an d 89 to 101% for plasma. Precision and accuracy (within-run and between-run ) studies reflected a high level of reliability and reproducibility of the method. In addition to its reliability, sensitivity and simplicity, this mo dified procedure is more efficient and cost effective, requiring less time, only 1 mt of sample, and minimal amounts of extraction solvents. The appli cability of the method for the detection and quantitation of clenbuterol in biological tissues of rats treated with the drug was demonstrated successf ully. For comparative analysis of clenbuterol in plasma and liver samples, both CC-MS and enzyme immunoassay (EIA) methods are found to be suitable. D ue to potential antibody-cross reactivity with EIA, the CC-MS method is the method of choice for most samples because of its specificity. However, the FIA method is considered the method of choice for analysis of clenbuterol found in concentrations below the limits of quantitation by CC-MS due to it s sensitivity. Copyright (C); 2000 John Wiley & Sons, Ltd.