Determination of 4 Degradation Products of Nonylphenol Ethoxylate in Luoyang River Water Body in Quanzhou by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

After the water samples were passed through the glass fiber filter membrane, an appropriate amount of 4-n-NP-d₄ internal standard solution was added into the filtrate until its mass concentration reached 10.0 μg·L^-1, and the mixed solution was vortexed for subsequent use. Sediment samples of 1 g or biological samples of 0.2 g after removing impurities, freeze-drying and grinding, together with 100 μL of 1 000 μg·L^-1 4-n-NP-d₄ internal standard solution, and 5.0 mL of methanol (sediment sample extraction solvent) or 5.0 mL of acetonitrile (biological sample extraction solvent) were mixed. The mixture was swirled for 30 s, extracted ultrasonically for 30 min, and centrifuged for 5 min. The extraction process was repeated once, and the supernatant was combined, of which the mass concentration of 4-n-NP-d₄ reached to 10.0 μg·L^-1. The obove solution was introduced into ultra-high performance liquid chromatograph-tandem mass spectrometer. Four degradation products of nonylphenol ethoxylate (NP1EO, NP2EO, 4-NP and 4-n-NP) were separated on the Shim-pack GIS C₁₈ column with mixed solutions composed of methanol and 1 mmol·L^-1 ammonium acetate solution at volume ratio of 95∶5 by isocratic elution, ionized by ESI^- mode (4-NP, 4-n-NP and 4-n-NP-d₄) and ESI⁺ mode (NP1EO and NP2EO), detected by MRM mode, and quantified by internal standard method. As shown by the results, linear ranges of standard curves were in the range of 1.0-20.0 μg·L^-1, with detection limits (3S/N) in the range of 0.03-0.29 μg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 70.8%-119%, and RSDs (n=6) of the determined values ranged from 1.5% to 8.7%. The proposed method was applied to the analysis of 50 samples of water, sediment, oyster and razor clam in Luoyang River water body, 4 targets were not detected in water sample, 4-n-NP was not detected in sediment and biological samples, while 4-NP、NP2EO and NP1EO could be detected to varying degrees, with detection amounts of the 3 targets in biological samples greater than those in sediment samples.