13C‐Isotope Labeled Surrogate for Estimating Organophosphorus Pesticides in Agricultural Products by Gas Chromatography‐Mass Spectrometry

13C-isotope labeled paraoxon-ethyl (13C2-EP) and deuterium-labeled paraoxon-methyl (D6-MP) were synthesized and employed as the surrogate (SS) and the internal standard (IS) in organophosphorus pesticides (OPs) spiking agricultural QC samples. The residual amounts of OPs were determined with gas chromatography-mass spectrometry (GC-MS) method. The isotope-labeled compounds used in this study could assist the analysts to estimate the appropriateness and the uncertainties produced by pre-treatment process. It was found that these isotope labeled compounds could improve the accuracy (10 % to 40 % of quantitative analysis), and provide efficacious calibration for the spiking recoveries of OPs in some agricultural samples.