| A new method was developed for the determination of three quaternary ammonium compounds(QACs) residues,including dodecyl dimethyl benzyl ammonium chloride(C12-BAC),hexadecyl dimethyl benzyl ammonium chloride(C16-BAC) and benzethonium chloride in ice creams using solid phase extraction(SPE) and ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The samples were melted and mixed,and then added into acetonitrile to extract target compounds and precipitate protein.The supernatant was purified with weak cationic exchange solid phase extraction cartridge(WCX) and concentrated in nitrogen stream.The separation of three quaternary ammonium compounds was performed on a Waters BEH HILIC column(50 mm×2.1 mm,1.7 μm) by isocratic elution using acetonitrile(containing 0.1% formic acid)-10 mmol/L ammonium acetate as mobile phase.The targets were analyzed under the multiple reaction monitoring(MRM)mode in positive electrospray ionization.The results showed that the calibration curves of three QACs were linear in the range of 0.5-20 μg/L with correlation coefficients greater than 0.999.The method quantitation limits(LOQs,S/N=10)of three analytes ranged from 3.0 μg/kg to 5.5 μg/kg.The average recoveries were in the range of 90.7%-102.2%,and the relative standard deviation(RSD,n=6) were 2.4%-6.4% at three spiked levels of standard.With the advantages of simplicity,accuracy,sensitivity and good reproducibility,the method could be used for the determination of QACs residues in ice creams.
Key words：quaternary ammonium compounds;ice creams;ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS);solid phase extraction(SPE) |