Rapid Determination of Isothiazolinone Residues in Milk Powder by Hydrophilic Interaction Liquid Chromatography-Tandem Mass Spectrometry

Abstract:

[Objective] A liquid chromatography-tandem mass spectrometry method was developed for rapid determination of 3 isothiazolinone residues in milk powder. [Method]Each sample was extracted twice with acetonitrile, and the extract was purified and enriched by Waters Prime HLB. The eluate was separated on a Waters BEH HILIC column (2.1 mm×100 mm×1.7 μm) and determined by quadrupole-MS/MS, and an isotopic internal standard method was employed for quantitation. [Result] The 3 isothiazolinones showed with good linearity (r≥0.995) within the range from 2.5 μg/kg to 250.0 μg/kg. The limits of detection (LOD) and the limits of qualification (LOQ) for the 3 isothiazolinones were 4 μg/kg and 10 μg/kg, respectively. The spiked recovery tests at three levels were conducted for the samples, and the spiked recoveries of the 3 isothiazolinones varied between 80.5% and 94.3%. The intra-batch and inter-batch coefficients of variation were 3.52%~10.95% and 6.64%~9.67%, respectively. [Conclusion]This method, with simple operation, short analysis time, high sensitivity, high accuracy, and high precision, is suitable for the determination of 3 isothiazolinone residues in milk powder.