Simultaneous determination of three acidic herbicide residues in food crops using HPLC and confirmation via LC‐MS/MS

Abstract 2,4‐D, dicamba and 4‐CPA with auxin‐like activity have been intensively used in agriculture, for the control of unwanted broadleaf weeds. An analytical method involving HPLC coupled with UVD was developed for the simultaneous analysis of these three analytes in Chinese cabbage, apple and pepper fruits (representative non‐fatty samples) and brown rice and soybean (representative fatty samples) using liquid‐liquid partitioning and column cleanup procedures. The residues were confirmed via tandem mass spectrometry (MS/MS) in ion electrospray ionization (ESI) mode. The standard curves were linear over the range of the tested concentrations (0.25–10 µg/mL), as shown by a marked linearity in excess of 0.9999 ( r 2 ). The average recoveries (mean, n = 3) ranged from 94.30 to 102.63 in Chinese cabbage, from 94.76 to 108.47 in apple, from 97.52 to 102.27 in pepper, from 76.19 to 101.90 in brown rice, and from 74.60 to 107.39 in soybean. The relative standard deviations (RSDs) were <9% in all tested matrices. The limits of detection and quantitation were 0.006 and 0.02 mg/kg, respectively. Samples purchased from local markets were analyzed to evaluate the applicability of the methods developed herein. The concentration of the 2,4‐D residue was measured at 0.102 mg/kg in the soybean sample; however, this level is exactly the same MRL set by the Korea Food and Drug Administration. This developed method deserves full and complete consideration, as it clearly displays the sensitivity, accuracy and precision required for residue analysis of 2,4‐D, dicamba and 4‐CPA in food crops. Copyright © 2010 John Wiley & Sons, Ltd.