Abstract: The by-product anion content was an important index for the evaluation of pesticide glyphosate’s productivity technology. A method was developed for the simultaneous determination of glyphosate, phosphorous by-products and other trace impurity anions in the mother liquor of glyphosate procedure by ion chromatography (IC). The sample was diluted with deionized water and filtrated by 0.22 μm nylon filter membrane, and then analyzed by IC directly without anymore pretreatment. The analytical column was Dionex IonPac AS11-HC (250 mm×4 mm) with a guard column IonPac AG11-HC (50 mm×4 mm). Gradient KOH eluent generated by an eluent generation cartridge was used at a flow rate of 1.0 mL/min. The detection was performed by a Dionex suppressed conductivity detector. The quantitative analysis of external standard calibration curves was used. The linear ranges of the method for glyphosate, methyl glyphosate, hexamethylphosphoramide (HMPA), glyphosine, phosphite, phosphate, chloride and sulfate were 0.1~20 mg/L (r=0.9995), 0.1~20 mg/L (r=0.9993), 0.1~50 mg/L (r=0.9999), 0.25~50 mg/L (r=0.9998), 0.05~20 mg/L (r=0.9999), 0.2~50 mg/L (r=0.9985), 0.02~20 mg/L (r=0.9999) and 0.05~50 mg/L (r=0.9980), respectively. The average recoveries were 93.7%~104.0% with the relative standard deviations less than 2.5% (n=7), and the detection limits (S/N=3) were 0.002~0.025 mg/L. The method has been applied to determine the contents of glyphosate, phosphorous by-products and inorganic anions in the mother liquor of glyphosate with satisfactory results.

Key words: glyphosate, inorganic anions, phosphorous by-products, ion chromatography (IC)