Determination of 3 isothiazolinone biocides in paper for cigarette by liquid chromatography-tandem mass spectrometry

In order to accurately determine the residues of isothiazolinone biocides in paper for cigarette (cigarette paper, plug wrap, inner liner and tipping paper), a rapid liquid chromatography-tandem mass spectrometry(LC-MS/MS) method for determining three isothiazolinone biocides (2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one and 1, 2-benzylisothiazolin-3-one) was developed. The paper sample was ultrasonically extracted with methanol, then the extract was centrifuged, the supernatant liquid was filtrated and then injected into LC-MS/MS and separated in a fluorine phenyl column by using methanol-water as mobile phase. The analytes were detected by LC-MS/MS under multiple reaction monitoring mode and quantified by an internal standard method. The results displayed that the recoveries of the proposed method ranged from 89.1% to 110.8%, and the relative standard deviations were not higher than 7.1% for all analytes. The LODs and LOQs were 0.014-0.018 and 0.045-0.059 mg/kg, respectively. This method is simple, accurate and suitable for the qualitative and quantitative analysis of trace isothiazolinone biocides in paper for cigarette.