Determination of 16 organic ultraviolet absorbers in drinking water by solid phase extraction-ultra-high performance liquid chromatography-tandem mass spectrometry

Organic ultraviolet absorbers （OUVAs） are a class of emerging contaminants that have garnered significant attention in recent years. In response to the characteristics of high detection frequency and low concentrations of OUVAs in water bodies， this study established an analytical method based on solid-phase extraction （SPE） coupled with ultra-high performance liquid chromatography-tandem mass spectrometry （UHPLC-MS/MS） for the simultaneous determination of 16 OUVAs （nine UV stabilizers and seven UV filters） in drinking water. The 500 mL water sample was pretreated with 25 mg ascorbic acid， acidified to pH 2-3， and spiked with 1 mL of 5 μg/L mixed internal standard working solution. Target compounds were enriched and concentrated using an HLB solid-phase extraction cartridge （200 mg/6 mL）. Separation was achieved on an Acquity Premier BEH C18 column （100 mm×2.1 mm， 1.7 μm） using a gradient elution with methanol and 2 mmol/L ammonium acetate aqueous solution as the mobile phases. Detection was performed using electrospray ionization in positive mode and multiple reaction monitoring （MRM）， with quantification carried out by the internal standard method. The precision and accuracy of the established method were evaluated using drinking water as the matrix. The results showed that all 16 OUVAs exhibited good linearity within their respective mass concentration ranges， with correlation coefficients （r） greater than 0.992. The method detection limits （MDL， S/N=3） were 0.03-5 ng/L， and the method quantification limits （MQL， S/N=10） were 0.1-15 ng/L. At spiked levels of 5， 20 and 50 ng/L， the recoveries of the target analytes ranged from 75.0% to 130.6%， with relative standard deviations （RSDs） ranging from 0.9% to 12.9% （n=6）. A total of seven source water samples and seven drinking water samples were analyzed using this method. The results showed that two OUVAs， 2-hydroxy-4-methoxybenzophenone （UV-9） and octocrylene （OC） were detected. In source water， the mass concentrations of UV-9 ranged from