Determination of Fasciolicide Residues in Milk Powder by Ultra-High Pressure Liquid Chromatography-Tandem Mass Spectrometry

A method for determination of common fasciolicide (Closantel, nitroxinil, rafoxanide, triclabendazole and ketotriclabnedazole) residues in milk powder using ultra-high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed. The samples were extracted with acetonitrile, and then cleaned-up with Captiva EMR-Lipid solid phase extraction column. The liquid chromatographic separation was carried out on a Waters CORTECS UPLC C18 column by a gradient elution with 5 mmol/L ammonium acetate solution-acetonitrile as mobile phases. Mass spectrometric analysis was conducted by multi-reaction monitoring (MRM) in electrospray negative ionization mode. The quantitative analysis was carried out by matrix-matched standard curve with r>0.997 in the concentration ranges of fasciolicide residues within 1.0-100.0 mu g/L. The limits of detection (LOD) and limits of quantification (LOQ) of this method were 0.58-1.10 mu g/kg and 2.61-4.95 mu g/kg, respectively. The recoveries of the spiked samples at three levels (5.0, 50.0 and 80.0 mu g/kg) ranged from 93.2% to 105.3% with the relative standard deviations (RSDs) from 1.2% to 8.9%, and the inter-RSDs were in the range of 2.8%-9.3%. The proposed approach, characterizing with high throughput and sensitivity, good accuracy and precision as well, could be effectively applicable to determination of fasciolicide residues in milk powder in routine detection as well as surveillance analysis.