Abstract:Quaternary ammonium compounds (QACs) were commonly used as the disinfectants to sterilize the production equipment during the production process of dairy products, which resulted in the QACs contamination in dairy products. A new method for the determination of five QACs in milk powder was established using QuEChERS purification coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Milk powder samples were dispersed into pro-rated water to obtain the liquid milk, and then precipitated by acetonitrile. The extract was analyzed in multiple-reaction monitoring (MRM) mode of MS/MS after purifying with PSA and separating with hydrophilic column (HILIC). Consequently, the five QACs showed a good linear relationship in concentration ranges of 0.2~50 μg/L, with the correlation coefficients over 0.999. This method was validated in terms of linearity, sensitivity, precision, accuracy. The limits of detections (LODs, S/N=3) for milk powder samples were in the range of ranged from4.0-14.4 μg/kg, and the recoveries were in the range of 96.5% - 115%.The relative standard deviations (RSDs) of intra-day precision and inter-day precision were 3.1-7.5% and 4.3~6.7%, which indicated that there were QACs residues in milk powder The proposed method demonstrated accuracy, sensitivity, rapidity, simplicity and good precision, which was suitable for the analysis and detection of five QACs in milk powder and other dairy products.
