Determination of residues of azaperone in the kidneys by liquid chromatography with fluorescence detection

An analytical method has been developed for the quantitative determination of residues of the tranquillizer azaperone (AZN) in the kidneys of slaughtered animals. Samples were extracted with acetonitrile, extracts were acidified and further purified with solid-phase extraction (SPE) on a polymeric mixed-mode cation-exchange sorbent, Oasis. AZN and its main metabolite azaperol (AZL) were eluted by alkaline methanol (MeOH), the eluate was evaporated, re-dissolved and analysed by gradient high performance liquid chromatography (LC) on reversed and deactivated phase LiChrospher 60-RP select B at excitation and emission wavelengths of 245 and 345 nm, respectively. The method was validated according to the requirements of European Commission Decision 2002/657/EC, using fortified porcine kidneys. The method proved to be selective, specific against carazolol (CAR) and linear over a concentration range 10-150 microg kg(-1) (r2>0.99). Over a concentration range 50-150 microg kg(-1), mean recovery of AZN and AZL was 88.2 and 91.2%, respectively, with intra-laboratory reproducibility of <11.0 and <9.0%, respectively. The decision limit (CCalpha) of AZN and AZL was 112 and 111 microg kg(-1), respectively, and the limit of quantification (LOQ) was 10 and 5 microg kg(-1), respectively. The procedure was also applied to bovine, poultry and horse kidneys, giving similar results, and has been successfully implemented in statutory residue monitoring control in food of animal origin in Slovenia.