Determination of clenbuterol in bovine urine using gas chromatography-mass spectrometry following clean-up on an ion-exchange resin.
A gas chromatographic-mass spectrometric method was developed for the determination of residues of clenbuterol in bovine urine. The method involves a simple cation-exchange clean-up and concentration of clenbuterol in the acidified urine, followed by ethyl acetate extraction. The analyte is determined as the di-trimethylsilyl derivative and quantitated against an internal standard of penbutolol. Using a 5-ml sample of urine, a detection limit of 0.07 ng/ml can be achieved with recoveries close to 100% for fortification levels of 0.2 and 1 ng/ml. By increasing the sample volume to 50 ml, a detection limit below 0.01 ng/ml was achievable with recovery averaging 70%. The coefficient of variation of the assay ranged from 15% at 0.01 ng/ml (50-ml sample) to 6% at 1 ng/ml (5-ml sample). It was demonstrated that the method can detect the presence of clenbuterol in bovine urine at sub-ppb (ng/ml) levels using low resolution GC-MS with electron impact (EI) ionization.
Whaites
L X
LX
Australian Government Analytical Laboratories, Pymble, NSW.
Murby
E J
EJ
D000818:Animals; D002411:Cation Exchange Resins; D002417:Cattle; D002852:Chromatography, Ion Exchange; D002976:Clenbuterol / Q000652:urine*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D002411:Cation Exchange Resins; D002976:Clenbuterol