Abstract:A method was developed for the determination of residues of six disinfectants, dodecyl dimethyl benzyl ammonium chloride, tetradecyl dimethyl benzyl ammonium chloride, benzyl dimethyl hexadecyl ammonium chloride, dodecyl trimethyl ammonium bromide, didecyl dimethyl ammonium chloride, and tetra butyl ammonium hydrogen sulfate, in goat milk using HPLC-MS/MS. Each sample was dissolved in hot water, extracted by ultrasonication followed by protein precipitation with acetonitrile, and separated using sodium chloride. Purification was performed using a Prime HLB SPE column before separation on a Hypersil GOLD C18 chromatographic column (100 mm×2.1 mm, 2.1 μm). Detection was conducted using electrospray ionization (ESI+) in selected reaction monitoring mode. Quantification of non-skimmed and skimmed goat milk powder samples was conducted using an external standard method specific to each blanked matrix type. The results demonstrated excellent linearity (correlation coefficients >0.999) within the concentration range of 0.01~5.0 μg/L for all six disinfectants, with detection limits (S/N≥3) and quantitation limits (S/N≥10) determined as 0.05 μg/kg and 0.10 μg/kg, respectively. Spiked recovery tests using goat milk powder samples yielded recoveries ranging from 97.07% to 105.6%, with relative standard deviations (n=6) between 0.987% and 4.576%. This method is highly sensitive, simple, and accurate for quantifying six disinfectant residues in goat milk powder, meeting the requirements for detection.
