No abstract

An HPLC method for the determination of glyphosate in formulation and technical samples has been subjected to a collaborative study with 12 laboratories participating. This method requires no sample pretreatment. Samples were dissolved in mobile phase, injected directly using a fixed-volume loop, and quantitated by an external standard technique. Compounds were separated on a strong anion exchange column with a water-methanol (96 + 4) mobile phase that was 0.0062M in KH2P04 and adjusted to pH 1.9 with 85% H3PO4, and detected with a variable wavelength UV detector at 195 nm. Calculations were made using peak areas. The collaborative study involved 3 pairs of matched samples with single determinations on each sample: Roundup herbicide, a technical intermediate, and technical glyphosate. The coefficients of variation for the 3 pairs were 1.70, 0.88, and 0.90%, respectively. The method has been adopted official first action.