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. Chromatographic separation was carried out on a TG-5 MS column (30 m × 0.25 mm × 0.25 μm) with helium as the carrier gas at a flow rate of 1.0 mL/min. Calibration curves were linear over 2.0–20.0 μg/mL for each analyte, and the limit of quantification was below 20 ng/mL. Good performance in terms 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.