Abstract:

A novel method was developed for the determination of 72 pesticide residues in tomato paste by TSQ
QUANTUMN GC (GC-MS/MS) combined with QueChers extraction. Optimal concentrations of standard working
solutions, SEM (selected ion monitoring) ion pairs, acquisition time window and collision energy were established for MS/
MS analysis of methamidophos and 71 other pesticides in full scan, daughter ion scan and selected ion scan modes. Over the
linear range of 5 to 2000 μg/L, the correlation coefficient for each pesticide was bigger than 0.99. Recoveries from spiked
samples at three levels indicated that 95.8% of the tested pesticides exhibited a recovery range of 80% to 120% with relative
standard deviation smaller than 15% for 87.5% of them. The limits of detection (RSN = 3) varied over the range of 0.04 to 7.5
μg/kg, and limits of quantification (RSN = 10) ranged from 0.1 to 12.9 μg/kg. This method could provide a sensitive, accurate
and reilable approach that meets the requirments for quantitative analysis of low levels of pesticides.

Key words: TSQ QUANTUMN GC, tomato paste, pesticide residue