QuEChERS-GC-MS/MS Determination of Residual Amount of 7 Amide Fungicides in Berries

An analytical method for determination of 7 residual amount of amide fungicides (metalaxyl, furalaxyl, benalaxyl, fenhexamid, benzoyl amine, cyflufenamidand thifluzamide) in berries by QuEChERS-GC-MS/MS was established in the work. 5.0 g of the berry samples were extracted by 20 mL of 1% (volume fraction) acetic acid-acetonitrile solution, then 5 g anhydrous magnesium sulfate was used to salt out. The extracted solution obtained was purified by N-propyl ethylenediamine, C₁₈ and graphitized carbon black, and centrifuged at 6 000 r·min^-1 rotation speed. The supernatant was taken and evaporated to near-dryness by N₂-blowing at 60℃, and dissolved and diluted to 1.0 mL with n-hexane, then filtered through a 0.2 μm filter membrane. The filtrate was introduced to DB-5MS chromatographic column (30 m×0.25 mm, 0.25 μm) and separated under the programmed temperature elevation, and then analyzed by MS/MS with MRM mode. Internal standard method was used in quantitative analysis. Linearity ranges of 7 amide fungicides were found in the same range of 0.04-4.0 mg·L^-1, with detection limits (3S/N) of 0.001-0.003 mg·kg^-1. Tests for the spiked recovery were made at 3 concentration levels for the grape samples, giving results of recovery ranged from 86.2% to 100%. Values of RSDs (n=6) found were in the range of 1.6%-4.1%.