Analysis of glyphosate and aminomethylphosphonic acid by capillary electrophoresis with electrochemiluminescence detection

A capillary electrophoresis (CE) method coupled with electrochemiluminescence (ECL) detection for the analysis of glyphosate (GLY) and its major metabolite aminomethylphosphonic acid (AMPA) is presented. Complete separation of GLY and AMPA was achieved in 8 min using a background electrolyte of 20 mM sodium phosphate (pH 9.0) and a separation voltage of 21 kV. ECL detection was performed with an indium tin oxide (ITO) working electrode bias at 1.6 V (vs. a Pt-wire reference) in a 300 mM sodium phosphate buffer (pH 8.0) containing 3.5 mM Ru(bpy)32+ (where bpy = 2.2′-bipyridyl). Linear correlation (r ≥ 0.997) between ECL intensity and analyte concentration was obtained in the ranges 0.169–16.9 and 5.55–111 μg ml−1 for GLY and AMPA, respectively. The limits of detection (LODs) for GLY and AMPA in water were 0.06 μg ml−1 and 4.04 μg ml−1, respectively. The developed method was applied to the analysis of GLY in soybeans. The LOD of GLY in soybean was 0.6 μg g−1. Total analysis time including sample pretreatment was less than 1 h.