Gas-liquid chromatography and gas-liquid chromatography combined with mass spectrometry of a butyl ester formulation of (2,4-dichlorophenoxy) acetic acid.

A method is presented for the analysis of (2,4-dichlorophenoxy)acetic acid (2,4-D) in commercial formulations, together with concurrent detection and quantitation of related compounds. The method is based on direct gas-liquid chromatographic (GLC) analysis of the formulation to estimate the various esters present, and on an analysis of the total 2,4-D present involving a prior cleanup, alkaline hydrolysis, acidification and n-butylation steps. This procedure also quantitates any other related acids or phenols present. A step which would extract dioxin impurities is also included. The method was checked by the accepted acid-base estimation of 2,4-D content, GLC, and by subjecting radioactive-labelled herbicide to the above procedures.