Quantitative Analysis of Organic Phosphonates, Phosphonate, and Other Inorganic Anions in Plants and Soil by Using High-Performance Ion Chromatography

Abstract

The current analytical method for quantitation of the systemic fungicide aluminum tris-O-ethyl phosphonate (Aliette) and its anionic metabolite phosphonate (HPO3-2) in plants is extremely tedious and requires the use of both high-pressure liquid chromatography and gas-liquid chromatography. We report here a simple and improved method that employs high-performance ion chromatography, using eluent suppression and conductivity detection, to determine residues of ethyl, diethyl, and dimethyl phosphonate, as well as the inorganic anions HPO3-2, HPO4-2, NO3-, and SO4-2 in aqueous extracts of plants and soil. The method has proved sensitive, reproducible, and requires only simple sample preparation. Two types of column and eluent are employed, one for inorganic anions and the other for organic phosphonate compounds. The efficiency of aquenous extraction of ethyl phosphonate and HPO3-2 from plants is about 70%. Aqueous extraction efficiency of organic phosphonates from soil is 90%, whereas that of HPO3-2 using 0.5 M NaHCO3 is 85%. Under the conditions employed, the limits of detection of the organic phosphonates from plants and soil are 2.0 microgram/g and 5.0 microgram/g, respectively; those of HPO3-2 and other inoganic anions in plants and soil are 0.5 microgram/g and 0.2 microgram/g, respectively