Simplified method for derivatization of extractable glyphosate and aminomethylphosphonic acid and their determination by high performance liquid chromatography

Abstract

This work presents a simple procedure for pre-column derivatization of glyphosate and aminomethylphosphonic acid(AMPA) and their determination by high-performance liquid chromatography (HPLC). Derivatization was achieved bymixing a solution of 0.02 M FMOC-Cl, 0.05 M borate buffer and glyphosate or AMPA, then shaken for 1 hour, laterwashed with diethyl ether and ready for analysis. The quantification was performed by HPLC with fluorescent (FLD)or diode array detector (DAD). The result of the HPLC-FLD/DAD showed high linearity ($R^2$ ≥ 0.995) of bothcompounds over eight point’s concentration range and their high recovery from water compared to soil matrixes. Therelative standard deviation (RSD) range from 0.1 to 30 % from the aforementioned matrixes. The limit of detection ofHPLC-FLD for glyphosate from water, sandy and clay soil was 0.008 mg $L^{-1}$, 0.021 and 0.132 mg $kg^{-1}$ respectively whilethat of AMPA was 0.004 mg L-1, 0.74 and 0.224 mg $kg^{-1}$. Meanwhile, the limit of detection of HPLC-DAD for glyphosatefrom water, sandy and clay soils was 0.024 mg $L^{-1}$, 0.731 and 0.122 mg $kg^{-1}$ respectively while that of AMPA for watersample was 0.076 mg $L^{-1}$. This study was unable to determine lower detection limit for AMPA from soil matrixes byHPLC-DAD thus suggested for more repeated extraction for increasing quantification of the compound.