Determination of pendimethalin in water, sediment, and Procambarus clarkii by high performance liquid chromatography-triple quadrupole mass spectrometry

We established a high-performance liquid chromatography-triple quadrupole mass spectrometry method for the analysis of pendimethalin residues in water, sediments, and Procambarus clarkii (Louisiana crayfish) tissues. Water samples were concentrated on a HLB solid-phase extraction column and eluted with dichloromethane and acetone (1:1). After drying under a stream of nitrogen gas, the sample volume was adjusted to 1 mL with the mobile phase solvent methanol/water/acetic acid (8:20:0.1). Pendimethalin was extracted with ethyl acetate containing 0.1% acetic acid, after rotary evaporation to dryness at 35 °C, the residue was dissolved in mobile phase solvent, purified by a neutral alumina column and graphitized carbon black powder (0.1 g). The mass characterization was conducted in positive ion mode, and the corresponding ions were detected in multi-reaction monitoring mode. The linear equations were y = 1 × 10⁶x + 14275, at pendimethalin levels of 0.05-20 μg L^-1 and y = 691029 × - 414368 for 20-200 μg L^-1. The detection limits of pendimethalin in water, sediments, and P. clarkii tissues were 1.0 × 10^-4μg L^-1 , 5.0 × 10^-3μg kg ^-1 and 5.0 × 10^-3 μg kg ^-1, respectively. The spiked recoveries ranged from 81.6 to 106.3%, and the relative standard deviations ranged from 4.58 to 13.6% (n = 6). The method provided an efficient and low-cost extraction and purification procedure that enabled a sensitive determination of pendimethalin in water as well as complex matrices.