Detection of herbicide clopyralid at nanogram per gram level in agricultural products using easy-to-use micro liquid–liquid extraction followed by analysis with ultraperformance liquid chromatography–tandem mass spectrometry
2020
Watanabe, Eiki | Seike, Nobuyasu
A new sample preparation method was developed for auxin-like herbicide clopyralid residue in agricultural products. The method uses extraction with sulfuric acid – acidified acetonitrile, with cleanup of sample extracts using solid-phase extraction (diatomaceous earth) and micro liquid–liquid extraction, followed by ultraperformance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). This sample preparation method greatly reduces the influence on ionization during determination with UPLC–MS/MS. Quantification was achieved using external calibrators prepared in matrix-free 0.1% formic acid. The proposed analytical method supported good recovery of 73.7–91.4% with less than 8% relative standard deviation. Method quantification limits (MQL) of samples were 0.6–1.0 ng g–¹. The method was applied to determine clopyralid residue in several crop samples. The herbicide was detected as near the MQLs in all samples.
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