Development of a more specific and accurate multiple reaction monitoring method based on GC–EI/MS/MS for simultaneously monitoring and determining 34 kinds of pesticides in Qianjinzhidai pills

• Thirty-four kinds of pesticides were monitored and determined by GC–EI/MS/MS.
• A novel optimization method about ion transitions was provided.
• This method can enhance the specificity of mass spectrum monitoring.
• This method can improve the accuracy of content determination.

A rapid and accurate multi-residue method was developed for simultaneously monitoring and determining 34 kinds of pesticides by GC–EI/MS/MS, successfully applied in Qianjinzhidai pills. Precision, repeatability, stability, limit of detection (LOD), limit of quantification (LOQ), linearity range and accuracy tests were used to validate this method. The results, precision (RSD < 2%, n = 6), repeatability (RSD < 2%, n = 6) and stability (RSD < 2%, n = 6), LOD (lower than 0.02 mg/kg), LOQ (lower than 0.067 mg/kg), linearity range (0.016–39.270 μg/mL), recoveries (90–110%, RSD < 15%, n = 6), indicated that the method was feasible. This paper provided an optimization method about ion transitions which can improve the specificity of mass spectrum monitoring and the accuracy of content determination. This method can be also used to monitor and determine pesticide residues of other traditional Chinese medicine, but it was worth noting that the ion transitions should been again optimized according to the sample matrix.