## 3 Results and Discussion
### Establishment of LC-MS/MS MRM Conditions  
The precursor ion was determined using a full scan analysis of 0.1 mg mL\({}^{-1}\) of each pesticide without an LC column. By comparing the ionization intensities in the positive and negative modes, at the same time, ions with optimal sensitivity, such as [M + H]\({}^{+}\), [M - H]\({}^{-}\), and [M + NH\({}_{4}\)]\({}^{+}\) were set as precursor ions. Using the determined precursor ions, product ions at various CE voltages were searched using the MRM optimization tool, and ions suitable for double quantification/qualification were determined. Using the established MRM conditions, the RT of the pesticides was measured using an analysis method optimized in this study. LC-MS/MS MRM conditions are listed in Tables 2 and S2. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Pesticides**} & \multirow{2}{*}{**RT (min)**} & \multicolumn{4}{c}{**Precursor \textgreater{} Product Ion (CE, eV)**} \\ \cline{3-6}  & & & \multicolumn{2}{c}{**Quantiifier Ion**} & \multicolumn{2}{c}{**Qualifier Ion**} \\ \hline \multicolumn{6}{c}{**Quantiifier Ion**} \\ \hline Abametcin B1 & 12.987 & M + NH\({}_{4}\)\({}^{+}\) & 890.6 \(>\) 305.25 & \(-\)29 & 890.6 \(>\) 567.3 & \(-\)15 \\ Acephate & 3.990 & M + H\({}^{+}\) & 184 \(>\) 143 & \(-\)10 & 184 \(>\) 95.15 & \(-\)24 \\ Acetamiprid & 4.636 & M + H\({}^{+}\) & 223.1 \(>\) 126.15 & \(-\)21 & 223.1 \(>\) 99.05 & \(-\)38 \\ Aldicarb & 5.143 & M + NH\({}_{4}\)\({}^{+}\) & 207.9 \(>\) 89.1 & \(-\)16 & 207.9 \(>\) 70 & \(-\)15 \\ Amisulbrom & 9.993 & MCI\({}_{35}\) + H\({}^{+}\) & 465.8 \(>\) 226.95 & \(-\)18 & 467.8 \(>\) 228.85 & \(-\)21 \\ Azimsulfuron & 6.131 & M + H\({}^{+}\) & 424.9 \(>\) 182.1 & \(-\)17 & 424.9 \(>\) 156.05 & \(-\)34 \\ Azimphos-methyl & 6.592 & M + H\({}^{+}\) & 317.9 \(>\) 132 & \(-\)13 & 317.9 \(>\) 159.9 & \(-\)7 \\ Azoxystrophin & 6.840 & M + H\({}^{+}\) & 404.1 \(>\) 372.2 & \(-\)15 & 404.1 \(>\) 344.2 & \(-\)25 \\ Bendiocarb & 5.430 & M + H\({}^{+}\) & 224.1 \(>\) 109.15 & \(-\)16 & 224.1 \(>\) 167.1 & \(-\)9 \\ Bensulfuron-methyl & 6.644 & M + H\({}^{+}\) & 411 \(>\) 149.15 & \(-\)21 & 411 \(>\) 119.1 & \(-\)39 \\ Benthiavalicarb-isopropyl & 7.474 & M + H\({}^{+}\) & 382.2 \(>\) 180.1 & \(-\)30 & 382.2 \(>\) 116.15 & \(-\)21 \\ Benzobicyclo & 7.433 & M + H\({}^{+}\) & 446.9 \(>\) 257.2 & \(-\)25 & 446.9 \(>\) 229.05 & \(-\)36 \\ Benzoximate & 9.386 & M + H\({}^{+}\) & 364 \(>\) 199.1 & \(-\)9 & 364 \(>\) 105.1 & \(-\)22 \\ Biterland & 9.381 & M + H\({}^{+}\) & 338.1 \(>\) 70.1 & \(-\)9 & 338.1 \(>\) 99.1 & \(-\)15 \\ Boscalid & 7.198 & M + H\({}^{+}\) & 343 \(>\) 307.2 & \(-\)20 & 343 \(>\) 140.1 & \(-\)21 \\ Bromacil & 5.574 & M + H\({}^{+}\) & 261 \(>\) 205.05 & \(-\)14 & 261 \(>\) 188 & \(-\)28 \\ Buprofezin & 10.702 & M + H\({}^{+}\) & 306.2 \(>\) 201.2 & \(-\)12 & 306.2 \(>\) 116.1 & \(-\)15 \\ Cadusafos & 9.912 & M + H\({}^{+}\) & 271.1 \(>\) 159.05 & \(-\)12 & 271.1 \(>\) 97.05 & \(-\)34 \\ Cafenstrole & 7.699 & M + H\({}^{+}\) & 351.1 \(>\) 100.15 & \(-\)10 & 351.1 \(>\) 72.2 & \(-\)28 \\ Carbaryl & 5.677 & M + H\({}^{+}\) & 202.1 \(>\) 145.2 & \(-\)13 & 202.1 \(>\) 127.15 & \(-\)25 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: MRM conditions for the first 40 pesticides in the LC–MS/MS analysis. MRM conditions for the other 179 pesticides are listed in Table S2.