Determination of Glyphosate asN-Nitroso Derivative by High Performance Liquid Chromatography with Chemiluminescence Detection

Glyphosate (GP) is a non-selective, postemergence herbicide widely used for weed and vegetative control. This paper describes a method for the determination of GP that is based on: a) nitrosation of GP to N-nitroso-GP (NGP), b) HPLC separation on an anion-exchange column, c) post column denitrosation of NGP to nitric oxide, and d) chemiluminescence determination of the liberated nitric oxide by a thermal energy analyzer. The method was applied to the determination of GP in water, beer and ale, lentils and beans, and a few cereals. Sample extracts were cleaned-up on mini anion-exchange columns prior to nitrosation. The recoveries of GP added to various samples at 0.01 to 6 μg/g levels ranged between 67–100% with the minimum detection limits ranging between 0.005 to 1 μg/g. The technique will be useful for detection of maximum residue limits (1 to 15 μg/g) of GP in most crops as permitted under Canadian Food and Drugs Regulations.