DETERMINATION OF WATER-SOLUBLE ORGANOPHOSPHORUS HERBICIDES BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY DETECTION

摘要

There is a high risk for human exposure to organophosphorus pesticides through contaminated drinking water. Glyphosate, glufosinate, fosamine and ethephon are among the water-soluble herbicides used currently. Sensitive and rapid analytical methodologies are critical for evaluating their residuals in a broad variety of samples, including environmental waters. However, challenges arise from the inherent chemical properties of the herbicides: strong polarity, high solubility in water, insolubility in organic solvent (except ethephon), absence of chromophore or fluorophore in their molecular structures. So far very rare analytical methods are available for ethephon and fosamine, while glyphosate and glufosinate are often determined by gas chromatography, high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). Inductively coupled plasma mass spectrometry (ICP-MS) is sensitive, rapid, selective, and is more powerful when hyphenated with appropriate separation. For the analysis of glufosinate, glyphosate and its metabolite aminomethylphosphonic acid (AMPA), ICP-MS was recently coupled to CE or ion-pairing reversed-phase LC. This paper described the first method able to simultaneously quantify the four herbicides in environmental waters. The proposed IC-ICP-MS method is based on the anion-exchange chromatography separation followed by the online detection by ICP-MS. Its initial application to the analysis of natural reservoir waters and treated waters was satisfactory.