Nonderivatization method for determination of glyphosate, glufosinate, bialaphos, and their main metabolites in environmental waters based on magnetic metal-organic framework pretreatment

A novel magnetic metal-organic framework composite was prepared by a self-assembly approach. The material properties were characterized by Fourier-transform infrared spectroscopy, vibrating sample magnetometry, thermogravimetry and differential thermogravimetric analysis, and X-photoelectron spectroscopy. Then, the as-prepared material was used as an adsorbent and indicated great enrichment ability toward glyphosate, glufosinate, bialaphos, and their main metabolites aminomethylphosphonic acid and 3-methylphosphinicopropionic acid. Based on this, an efficient magnetic solid-phase extraction method combined with ultra high performance liquid chromatography with high-resolution mass spectrometry for the pretreatment and determination of five target compounds in environmental waters was established. Parameters that could impact on the adsorption performance had been studied in detail. The proposed method was successfully applied for the simultaneous determination of glyphosate, glufosinate, bialaphos, and their main metabolites aminomethylphosphonic acid and 3-methylphosphinicopropionic acid in environmental water with recoveries in range of 86.2-104.6% with relative standard deviations less than 10%. Desired linearity was achieved varying from 1 to 100 mu g/L for five target analytes, respectively. The limits of detection were between 0.01 and 0.03 mu g/L.