## 2 Results and Discussion
### Application for Survey of Fungicides in Fruits Samples  
The developed method was applied for the detection of fungicides in fruit samples bought from several supermarkets in China. A total of 81 fruit samples, including six types (grape, apple, pear, orange, yangtao, and watermelon), were detected, while 96.3% of them presented detectable levels of the target fungicides, the majority of which were carbendazim, with a positive frequency of 79.0% and a concentration region of 0.41 to 314.0 \(\upmu\)g\(\cdot\)kg\({}^{-1}\) (Table 5). Figure 5 presented a positive grape sample that detected carbendazim at 20.4 \(\upmu\)g/kg. It could be confirmed by dd-MS\({}^{2}\) spectra, as shown in Figure 5b, that the main fragments were found to be \(m\)/\(\upmu\) 160.05055, \(m\)/\(\upmu\) 133.06488, and \(m\)/\(\upmu\) 105.07025, owing to the fragments of [M+H-CH\({}_{3}\)OH]\({}^{+}\), [M+H-CH\({}_{3}\)OH-CO]\({}^{+}\), and [M+H-CH\({}_{3}\)OH-CO-C=N]\({}^{+}\), respectively. Other fungicides such as thiophanate-methyl, pyrimethanil, metalaxyl, prochloraz, procymidone, dimethomorph, and didenoconazolel were present in range of 3.7% to 49.4% of samples. The mean concentration of these varried from 1.2 \(\upmu\)g\(\cdot\)kg\({}^{-1}\) to 287.7 \(\upmu\)g\(\cdot\)kg\({}^{-1}\) (Table 5). Triadimefon could not be detected in all the analyzed fruits samples. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multicolumn{8}{c}{**Average Recovery, \% (RSD \({}^{1}\), \%)**} \\ \cline{2-10}  & \multicolumn{3}{c}{**Apple**} & \multicolumn{3}{c}{**Orange**} & \multicolumn{3}{c}{**Grape**} \\ \cline{2-10}  & **1.0** & **40.0** & **80.0** & **1.0** & **40.0** & **80.0** & **1.0** & **40.0** & **80.0** \\  & **\(\upmu\)g/kg** & **\(\upmu\)g/kg** & **\(\upmu\)g/kg** & **\(\upmu\)g/kg** & **\(\upmu\)g/kg** & **\(\upmu\)g/kg** & **\(\upmu\)g/kg** & **\(\upmu\)g/kg** & **\(\upmu\)g/kg** \\ \hline \multirow{2}{*}{**Carbendazim**} & 96.6 & 105.2 & 98.1 & 90.1 & 93.2 & 96.4 & 96.2 & 102.3 & 99.3 \\  & (8.2) & (2.1) & (1.4) & (7.1) & (4.2) & (2.5) & (5.3) & (1.8) & (1.8) \\ \hline \multirow{2}{*}{**Tniophanate-methyl**} & 95.2 & 103.2 & 101.5 & 89.4 & 90.8 & 90.2 & 96.3 & 98.9 & 103.6 \\  & (5.3) & (1.2) & (0.9) & (3.5) & (2.3) & (2.0) & (3.2) & (1.0) & (0.8) \\ \hline \multirow{2}{*}{**Pyimethanil**} & 90.2 & 94.5 & 96.2 & 87.1 & 91.2 & 94.7 & 92.5 & 96.2 & 98.7 \\  & (6.2) & (1.1) & (1.0) & (6.3) & (2.5) & (1.6) & (4.8) & (2.3) & (1.6) \\ \hline \multirow{2}{*}{**Metalaxyl**} & 95.3 & 96.7 & 97.5 & 93.4 & 95.3 & 95.8 & 94.2 & 97.8 & 99.1 \\  & (6.8) & (3.1) & (2.3) & (6.8) & (3.7) & (2.4) & (5.2) & (2.9) & (1.4) \\ \hline \multirow{2}{*}{**Prochloraz**} & 90.8 & 92.5 & 92.6 & 85.6 & 88.3 & 89.5 & 92.5 & 94.6 & 97.8 \\  & (6.9) & (2.6) & (1.8) & (6.2) & (2.8) & (1.9) & (4.7) & (3.2) & (1.9) \\ \hline \multirow{2}{*}{**Procymidone**} & 88.1 & 92.2 & 90.3 & 85.6 & 87.2 & 89.6 & 91.4 & 93.6 & 90.3 \\  & (7.2) & (3.2) & (2.1) & (7.8) & (4.2) & (3.1) & (6.2) & (2.8) & (1.6) \\ \hline \multirow{2}{*}{**Dimethomorph**} & 93.1 & 99.3 & 98.2 & 86.9 & 92.4 & 95.3 & 93.4 & 98.8 & 105.2 \\  & (5.2) & (4.2) & (2.4) & (6.4) & (4.0) & (3.5) & (5.4) & (3.6) & (2.1) \\ \hline \multirow{2}{*}{**Triadimefon**} & 86.3 & 89.6 & 90.2 & 85.6 & 89.5 & 91.3 & 86.5 & 89.8 & 92.6 \\  & (4.7) & (2.8) & (1.2) & (5.6) & (3.2) & (2.3) & (3.8) & (2.1) & (1.0) \\ \hline \multirow{2}{*}{**Difenoconazole**} & 85.2 & 88.1 & 91.2 & 84.9 & 86.7 & 93.5 & 89.7 & 89.5 & 93.3 \\  & (7.5) & (4.5) & (3.2) & (6.2) & (5.1) & (3.2) & (6.4) & (6.2) & (3.1) \\ \hline \hline \end{tabular} \({}^{1}\) RSD: relative standard deviation.  
\end{table} 
Table 4: Accuracy and precision of nine fungicides in three blank representative fruit samples spiked at three different concentrations by the developed method (\(n=6\), \(\upmu\)g\(\cdot\)kg\({}^{-1}\), \(\upmu\)g\(\cdot\)kg\({}^{-1}\)).