Determination of residual dimethyl sulfate in hexaconazole technical (fungicide) by head space gas chromatography mass spectrometry

Dimethyl sulfate is used as alkylating agent in manufacturing process but because of its genotoxicity nature it should be monitored at trace levels (1 mg/kg). A simple pre-column derivatization i.e. alkylation of butyl alcohol gives corresponding ether (methoxybutane) which is analyzed by head space gas chromatography mass spectrometry (HS-GC-MS). The retention time of derivative is 5.32 min. Analysis was carried out in Selected Ion Monitoring (SIM) mode. The linear regression analysis data for the calibration curve showed a good linear relationship with a regression coefficient of 0.999 in the concentration range of 0.035 mg/kg to 9.234 mg/kg. The method was validated for specificity, linearity, LOD, LOQ, precision and accuracy.