A simple, rapid and sensitive method was developed for the simultaneous determination of chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Samples were extracted with acetic acid solution, purified on an HLB column, and then filtered through a 0.2 μm hydrophilic microporous filter membrane. It was then separated on an IC column using a separation phase consisting of polyvinyl alcohol particles with quaternary ammonium groups. The mobile was optimised with water as mobile phase A and 200 mmol L-1 ammonium bicarbonate solution containing 0.05% ammonium hydroxide as mobile phase B. The residues were detected by tandem mass spectrometry with negative electrospray ionization in multi-reaction monitoring mode. The correlation coefficient (R ≥ 0.997) showed good linear regressions for all targets in water as well as in maize and soybean matrices with a wide dynamic range from 0.001 to 0.5 mg L-1 for calibration curves. The mean recoveries (RSDs) of the analytes were in the range of 85.0%-106.4% (5.5%-14.9%), 81.7%-109.5% (2.7%-11.0%) and 74.7%-104.4% (2.9%-6.1%) at three fortification levels (0.05, 0.1 and 1 mg kg-1) for the interday test (n = 15). The limit of quantification (LOQ) and detection (LOD) of the method in different matrices were 0.01 and 0.003 mg kg-1, respectively. The established analytical approach has high sensitivity, good accuracy and precision and is suitable for monitoring chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean.
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