A high-performance liquid chromatography-tandem mass spectrometric(HPLC-MS/MS) method was developed for the rapid determination of five quaternary ammonium salts

e.g.benzyldimethyldodecyl ammonium chloride，benzyldimethyltetradecyl ammonium chloride

benzyldimethylhexadecyl ammonium chloride

dodecyltrimethyl ammonium chloride

and didecyldimethyl ammonium chloride

in frozen drinks.The samples were extracted twice with acetonitrile-ethyl acetate(1∶1，by volume)

then frozen to degrease at-20 ℃.The extract was separated on a CAPCELL PAK CR(1∶20) column using acetonitrile-5 mmoL ammonium acetate containing 0.1% formic acid as mobile phase by gradient elution.The target analytes were detected in multiple-reaction monitoring(MRM) mode

and quantified by the matrix matched external standard method.Results showed that good linearities for the five quaternary ammonium salts existed in the mass concentration range of 0.5-50.0 μg/L

with their correlation coefficients(r) larger than 0.995.The limits of detection(LOD) and limits of quantitation(LOQ) were in the ranges of 0.3-1.5 μg/kg and 1.0-5.0 μg/kg

respectively.The average recoveries for the five analytes at three spiked levels of 5.0

10.0 and 50.0 μg/kg ranged from 80.3% to 114% with relative standard deviations(RSD) of 2.5%-83%.With the advantages of convenient operation

high sensitivity and good precision

this method is suitable for the determination of five quaternary ammonium salts in frozen drinks.