Determination of 29 adjuvants in pesticide formulations by gas chromatography-mass spectrometry

A method based on gas chromatography-mass spectrometry (GC-MS) was developed for the simultaneous determination of 29 adjuvants in pesticide formulations. The pesticide formulation was diluted with methanol, and the supernatant was filtered through a 0. 22- tim membrane. After separation on a VF-1701MS column, the analytes were detected by mass spectrometry in the selected ion monitoring (SIM) mode and quantified using the external standard method. Good linearities were obtained for the 29 pesticide adjuvants in the linear range of 6. 2 -400. 0 mg/L, with correlation coefficients (R-2) larger than 0. 99. The limits of quantification (LOQs) were 4. 4-439. 1 mg/kg. The average recoveries in emulsifiable concentrate (EC) and soluble concentrate (SL) samples ranged from 82. 0% to 111. 9% and from 82. 6% to 112. 9%, respectively. The relative standard deviations (RSDs, n = 6) ranged from 0. 4% to 7. 2% and from 0. 3% to 8. 2%, respectively. Finally, 110 pesticide formulation samples were detected; 11 kinds of pesticide adjuvants, including phenol, N-methyl pyrrolidone, dichloromethane, and n hexane, were detected in 28 samples with contents ranging from 0. 05% to 15. 65%. The proposed method is simple, sensitive, and accurate, and is suitable for the simultaneous determination of the 29 adjuvants in pesticide formulations.