## 3 Results and Discussion
### Analytical Performance  
In Table 1, the matrix-matched standard curves for all insecticides exhibited good linearities in the range of 0.1-100 ng g\({}^{-1}\). The determination coefficients (R\({}^{2}\)) were satisfactory, with the values from 0.9975 to 0.9998. The LOD values of all insecticides ranged from 0.006 to 0.03 ng g\({}^{-1}\), depending upon the type of the analyte, while the LOQ values were 5 ng g\({}^{-1}\) for thirteen insecticides analyzed, and these values were sufficient to achieve the required sensitivity for target insecticides analyses. Additionally, the intra-day relative standard deviations (RSDs) and inter-day RSDs were in the range of 2.8-7.1% and 3.5-8.8%, respectively. The validation results indicated good linearity, sensitivity, and precision of the method. To further evaluate the applicability of the developed method, it was used for the determining of the insecticide residues in tomato, cucumber, and pakchoi samples, bought from the local supermarket. According to Table 2, 4.7 ng g\({}^{-1}\) bifenthrin and 4.9 ng g\({}^{-1}\) lambda-cylaholtrin were detected in cucumber and pakchoi, respectively, which were lower than the MRLs. The recovery of thirteen insecticides (79.2-109.4%) were in the range of 70-120%, as set by the European Commission, Health and Consumer Protection Directorate-General [33]. The RSDs were below 11.2%, meeting the requirements of pesticide residue analysis (RSD \(\leq\) 20%) [33]. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Analytic**} & \multirow{2}{*}{**Regression Curves**} & \multirow{2}{*}{\begin{tabular}{c} **Linearity** \\ **(ng g\({}^{-1}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **R\({}^{2}\)** \\ **(ng g\({}^{-1}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **LODs** \\ **(ng g\({}^{-1}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **LOQs** \\ **(ng g\({}^{-1}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **MRLs** \\ **(ng g\({}^{-1}\))** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Intraday** \\ **(n = 5)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Inter-Day** \\ **(n = 15)** \\ \end{tabular} } \\ \hline Isocarbphos & Y = 17,453X + 4380 & 5–100 & 0.9993 & 0.03 & 5 & 50 & 4.5 & 5.1 \\ Quinalphos & Y = 162,933X - 43,204 & 5–100 & 0.9998 & 0.009 & 5 & - & 3.6 & 4.5 \\ Phorate & Y = 23,107X + 9314 & 5–100 & 0.9975 & 0.009 & 5 & 10 & 4.6 & 7.0 \\ Chlorpyifos & Y = 91,978X - 27,323 & 5–100 & 0.9986 & 0.009 & 5 & 10–1000 & 2.5 & 4.5 \\ Phosalone & Y = 202,702X + 34,570 & 5–100 & 0.9995 & 0.01 & 5 & 1000 & 6.8 & 8.8 \\ Pirmor & Y = 42,473X + 37,167 & 5–100 & 0.9996 & 0.01 & 5 & 10–5000 & 3.3 & 5.2 \\ Carbaryl & Y = 39,737X + 39,214 & 5–100 & 0.9990 & 0.01 & 5 & 20–5000 & 2.8 & 6.4 \\ Mycobutanil & Y = 637,361X - 4792 & 5–100 & 0.9972 & 0.006 & 5 & 50–3000 & 3.4 & 3.7 \\ Diniconazole & Y = 162,443X - 37,706 & 5–100 & 0.9991 & 0.006 & 5 & 50 & 5.5 & 5.2 \\ Lambda-cylaholtrin & Y = 111,654X - 53,779 & 5–100 & 0.9992 & 0.03 & 5 & 10–5000 & 7.1 & 3.6 \\ Bifenthrin & Y = 698,826X - 193,428 & 5–100 & 0.9993 & 0.01 & 5 & 50–4000 & 2.6 & 3.5 \\
2, 4’-DDT & Y = 121,476X - 22,140 & 5–100 & 0.9992 & 0.01 & 5 & 50–200 & 4.8 & 4.1 \\ Mirex & Y = 239,134X - 137,874 & 5–100 & 0.9998 & 0.01 & 5 & 10 & 3.0 & 4.2 \\ \hline \hline \multicolumn{7}{c}{MRLs represent the maximum residue limits of insecticides in vegetables, as recommended by the National Food Safety Standard (China, GB 2763-2019). Intraday data and inter-day data were evaluated using one-way ANOVA with “day” as the grouping variable.} \\ \end{tabular}
\end{table} 
Table 1: The linearity, determination coefficients, LOD, LOQ, and RSD for insecticides in the tomato sample. Generally, the co-elution of matrix constituents can interfere with the ionization of the target compounds, causing ion enhancement or suppression. The matrix effect caused a signal enhancement or suppression of the analytes, which could affect the quality of the quantitative data, achieved from the method.