Confirmatory method for the determination of nandrolone and trenbolone in urine samples using immunoaffinity cleanup and liquid chromatography-tandem mass spectrometry.

A confirmatory method for the simultaneous determination of nandrolone (alpha and beta) and trenbolone (alpha and beta) in urine samples by liquid chromatography electrospray mass spectrometry (LC-MS-MS) was developed. After an enzymatic deconjugation, the urine was subjected to a one-step cleanup on a commercially available immunoaffinity chromatography cartridge. The analytes were detected by liquid chromatography-positive ion electrospray tandem mass spectrometry using deuterium labelled internal standards. The analytical procedure was applicable to bovine and swine urine samples. The procedure was validated as a quantitative confirmatory method according to the Commission Decision 2002/657/EC criteria. The results obtained showed that the method was suitable for statutory residues testing regarding the following performance characteristics: instrumental linearity, specificity, precision (repeatability and intra-laboratory reproducibility), recovery, decision limit (CCalpha), detection capability (CCbeta) and ruggedness. The decision limits (CCalpha) obtained, were between 0.54 and 0.60 microg L(-1); the recovery was above 64% for all the analytes. Repeatability was between 1.6% and 5.7% and within-laboratory reproducibility between 1.6% and 6.0% for all the steroids.