Direct determination of n-nitrosoglyphosate in technical glyphosate using ion chromatography with UV detection

Abstract

The official method for analyzing N-nitrosoglyphosate (NNG), a relevant impurity, in glyphosate matrix demands complicated instrumentation and operating conditions not available in many laboratories. In this work, we developed a direct, simple, selective and sensitive ion chromatography (IC) method with UV detection for the determination of NNG in samples of technical glyphosate. To separate NNG from the matrix we used an IC anionic column mounted in a high-performance liquid chromatography (HPLC) apparatus equipped with a photo-diode array detector. The system used a high ionic strength eluent. The method was validated, taking into account the following figures of merit: selectivity, linearity, repeatability, intermediate precision, recovery, limit of detection (LOD), and limit of quantification (LOQ). The proposed method is sensitive enough to quantify NNG below the maximum concentration determined by both the Food and Agricultural Organization of the United Nations (FAO) and the Brazilian regulation.