Direct Determination of 2,4-dichlorophenoxyacetic acid in Soybean and Corn by Liquid chromatography/tandem mass spectrometry

Narong Chamkasem, Cynthia Morris


A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of 2,4-dichlorophenoxy acetic acid (2,4-D) in soybean and corn using a reversed-phase with weak anion-exchange and cation-exchange mixed-mode Acclaim™ Trinity™ Q1 column. The method involved an alkaline hydrolysis with sodium hydroxide in order to convert all forms of 2,4-D into a salt form prior to extraction with acidified acetonitrile. The acetonitrile was salted out of the extract with sodium chloride and magnesium sulfate. The acetonitrile extract was diluted 1:1 with water and filtered before analysis by LC-MS/MS in a negative mode. Recoveries were evaluated at 10, 100, and 500 ng/g with seven replicates. Mean recovery ranged from 86 to 107% with relative standard deviation of less than 10%.  Matrix suppression was not observed in this procedure; therefore, no internal standard was needed. The method was used successfully for the determination of 2,4-D in soybean and corn samples containing incurred residue. The procedure proved to be quick, accurate, precise, sensitive, and selective.


2,4-D, soybean, corn, LC-MS/MS, direct determination.

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