The determination of underivatized chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean by LC-MS/MS.

In this study, 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). Analytes were extracted with acetic acid solution, purified on an HLB column, and then filtered through a 0.2 μm hydrophilic microporous filter membrane. They were then separated on an IC column using a separation phase consisting of polyvinyl alcohol particles with quaternary ammonium groups. The mobile phase optimised with water was denoted as mobile phase A and that optimised with 200 mmol L ammonium bicarbonate solution containing 0.05% ammonium hydroxide was denoted as mobile phase B. The residues were detected by tandem mass spectrometry with negative electrospray ionization in a multi-reaction monitoring mode. The correlation coefficient ( ≥ 0.997) showed good linear regressions for all analytes in water as well as in maize and soybean matrices with a wide dynamic range of 0.001 to 0.5 mg L for calibration. The mean recoveries (RSDs) of the analytes were in the range 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 concentration levels (0.05, 0.1 and 1 mg kg) for the interday test ( = 15). The limit of quantification (LOQ) and detection (LOD) of the method for different matrices were 0.01 and 0.003 mg kg, respectively. In conclusion, the established analytical approach has high sensitivity and good accuracy and precision and is suitable for monitoring chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean.