Determination of Residual Imazethapyr in Soybeans by Gas Chromatography/Nitrogen-Phosphorus Detection

Open Access
Publisher Website
Google Scholar
Abstract
Imazethapyr, a recently introduced imidazolinone herbicide, is registered for use on soybeans and other legumes in the United States and Canada. Its maximum allowed residue level in soybeans is 0.1 ppm. A method was developed to allow the measurement of ≥0.01 ppm imazethapyr on soybeans. The method exploits the ready cyclization of the nonvolatile acid to the volatile imidazoisoindol-3,5-dione by using an excess of easily removed, watersoluble carbodiimide and the selectivity of gas chromatography with nitrogen-phosphorus detection. A simple cleanup on a diol-bonded silica minicolumn reduces the complexity of the soybean extract. The derivatization works equally well for other imidazolinone herbicide acids. Because imidazoisoindolediones have characteristic fragmentation patterns, they are useful for mass spectroscopic confirmation of suspected residues.

This publication has 0 references indexed in Scilit: