A Method to Assess Glyphosate, Glufosinate and Aminomethylphosphonic Acid in Soil and Earthworms

A new sensitive and selective analytical methodology to quantify glyphosate (GLY), aminomethylphosphonic acid (AMPA), and glufosinate (GLU) in both soil and earthworms (Allolobophora chlorotica) was developed. The extraction and purification methods were optimized. The samples were extracted with various aqueous solutions (HNO3, H2O, KOH and borate buffer) and derivatized with 9-Fluorenylmethyl chloroformate (FMOC-Cl). To optimize the extraction step, a method to remove the excess FMOC-Cl was applied based on liquid-liquid extraction with diethyl ether. The purification of derivatized extracts was carried out using XLB solid phase extraction (SPE) cartridges before internal standard quantification by liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS). The elution step was optimized to obtain the best recoveries possible, which was with acidic methanol (1% formic acid) (67% for GLY, 70% for GLU and 65% for AMPA). The extraction and purification method followed by analysis of the two herbicides and AMPA in soils using LC/MS/MS determined limit of quantification (LOQ) values of 0.030 mu g g(-1) for GLY, 0.025 mu g g(-1) for AMPA and 0.020 mu g g(-1) for GLU. For earthworms, LOQ were 0.23 mu g g(-1) for GLY, 0.20 mu g g(-1) for AMPA and 0.12 mu g g(-1) for GLU.. The developed method was applied to determine these compounds in natural soils and earthworms. (C) 2021 Elsevier B.V. All rights reserved.