Effects of salt matrices on the determination of glyphosate, glufosinate, aminomethylphosphonic acid and 2-aminoethylphosphonic acid using reversed-phase liquid chromatography after fluorescence derivatization

Abstract

This study evaluated the effects of salt matrices on the determination of glyphosate (GLY), glufosinate (GLU), aminomethylphosphonic acid (AMPA) and 2-aminoethylphosphonic acid (2-AEP) in seawater samples, using reversed-phase liquid chromatography–fluorescence detection (LC-FLD) following fluorescence derivatization with 9-fluorenylmethyl chloroformate. Results showed that salinity can clearly improve the derivatization efficiency of GLY and extend the retention time of GLY derivative, while GLU, AMPA and 2-AEP were almost unaffected. In addition, the co-occurrence of metal ions (such as Fe3+, Cu2+, Zn2+, Mn2+, Co2+ and Mo6+) in seawater media did not induce any significant effect on the analysis of GLY, GLU, AMPA or 2-AEP. Calibration curves prepared at the same salinity level as test samples can accurately and effectively correct for any observed salt-matrix effects. The optimized method for the determination of GLY, GLU, AMPA and 2-AEP exhibited wide linear response ranges, with good linearity (R2 > 0.99), high repeatability (relative standard deviation ≤ 4.2%), low limits of detection (0.075–0.75 μg/L) and limits of quantification (0.25–2.5 μg/L) in seawater matrix. The reliability of this method was validated by successfully analyzing seawater medium samples, achieving a satisfactory range of recovery (75–125%).