BACKGROUND: Pinoxaden is the phenylpyrazoline herbicide developed by Syngeta Crop Protection, Inc. and marketed on 2006. The maximum residue level for wheat and barley were set by import tolerance. Thus, Ministry of Food and Drug Safety (MFDS) official analytical method determining Pinoxaden residue was necessary in various food matrixes. Satisfaction of international guideline of CODEX (Codex Alimentarius Commission CAC/GL 40) and National Institute of Food and Drug Safety Evaluation-MFDS (2006) are additional pre-requirements for analytical method. In this study, Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method was investigated to analyze residue of Pinoxaden (M4), which is defined as pesticide residue in Korea, in foods.
METHODS AND RESULTS: Pinoxaden (M4) was extracted followed by acid digestion (2hr reflux with 1N HCl) and pH adjusting (pH 4-5 with 3% ammonium solution). To remove oil, additional clean-up step with Hexane saturated with acetonitrile was required to high oil contained sample before purification. HLB cartridge and nylon syringe filter were used for purification. Then, samples were analyzed by LC-MS/MS using reserve phase column Unison C18. Five agricultural group representative commodities (mandarin, potato, soybean, hulled rice, and chilli pepper) were used to verify the method in this study. The liner matrix-matched calibration curves were confirmed with coefficient of determination (r2) > 0.99 at calibration range 0.002-0.2 mg/kg. The limits of detection and quantification were 0.004 and 0.01 mg/kg, which is suitable to apply Positive List System (PLS). Mean average accuracies of Pinoxaden (M4) were shown 74.0-105.7 %. The precision of Pinoxaden and its metabolites were also shown less than 14.5% for all five samples.
CONCLUSION: The method investigated in this study is suitable to CODEX (CAC/GL 40) and National Institute of Food and Drug Safety Evaluation Ministry of Food and Drug Safety (NIFDSEMFDS) (2006) guideline for residue analysis. Thus, this method can be useful for determining the residue in various food matrixes in routine analysis.