Development of method for residue analysis of three herbicides in the soil by high performance liquid chromatography (HPLC)

Abstract

Contamination of soil and water resources by herbicides is an increasing environmental concern. Soil plays an important role in agro-ecosystem and the environment, but information for analysis of herbicides residue in the soil can be very difficult to come by. Laboratory experiment was conducted to simplify analytical methods of the residue of paraquat, glyphosate, and glufosinate-ammonium in soil through development and modification from previously published methods. The high performance liquid chromatography (HPLC) system used for analyzing paraquat-dichloride consisted of model 600 controller multi-solvent delivery system, model 717 plus auto-sampler and model 2996 photodiode array detector. The HPLC system used to analyze glyphosate and glufosinate-ammonium consisted of model 501 solvent delivery system, model 7125 manual injector equipped with a 20 µl loop, and model 470 scanning fluorescence detector. Results showed that developed procedures and HPLC instruments used were acceptable, simple, easy, accurate, safe and efficient in separating paraquat, glufosinate-ammonium and glyphosate as indicated by the calibration curve and recovery of spiked soil samples. Using short and small size of C18 column and high flow rate produced shorter retention time of paraquat. Adding acetone and washing with ethyl acetate was important derivatization steps for glufosinate-ammonium and glyphosate. The improved methods can be used in evaluating herbicide residues in the soil and water easily and accurately. Key words: Herbicide residue, soil, HPLC, paraquat, glyphosate, glufosinate-ammonium.