Development and Validation of a GC-MS Method for the Simultaneous Determination of Acetochlor, Fluorochloridone, and Pendimethalin in a Herbicide Emulsifiable Concentrate Formulation

This paper describes a rapid method to simultaneously determine acetochlor, fluorochloridone and pendimethalin present in a herbicide emulsifiable concentrate (EC) formulation using gas chromatography-mass spectrometry (GC-MS). Selected ion monitoring mode was performed to increase the sensitivity, with dibutyl phthalate as an internal standard. The method was validated with respect to linearity, accuracy, precision, and stability. Chromato-graphic separation was carried out on a TG-5 MS column (30 m x 0.25 mm x 0.25 mu m) with helium as the carrier gas at a flow rate of 1.0 mL/min. Calibration curves were linear over 2.0-20.0 mu g/mL for each analyte, and the limit of quantification was below 20 ng/mL. Good performance in teens of recovery ranging from 94.5% to 102.5% at 3 concentration levels proved excellent accuracy. The intra- and inter-day relative standard deviations for 6 replicate measurements were always less than 5%. The developed method is simple and efficient for the routine determination of the ternary mixtures in a compound herbicide EC formulation product.