[Dispersive liquid-liquid microextraction based on solidification of floating organic droplets combined with high performance liquid chromatography-tandem mass spectrometry for determination of benzotriazole ultraviolet stabilizers in seawater].

A novel dispersive liquid-liquid microextraction method based on solidification of floating organic droplets (DLLME-SFO) technique was developed for the determination of seven benzotriazole ultraviolet (UV) stabilizers in seawater samples by high performance liquid chromatography with tandem mass spectrometry. The optimal liquid-liquid microextraction experiment conditions were as follows: 20 μL of 1-dodecanol as extraction solvent, 400 μL of methanol as dispersive solvent, 8% (mass percentage) NaCl, pH of the sample below 6, vortex oscillation extraction time in 2 min. The separation of target compounds was achieved by combining a Hypersil GOLD analytical column (150 mm x 2.1 mm, 5 μm) with methanol-water as mobile phase with gradient elution program. Quantitative determination by ESI-MS/MS was achieved using positive ion mode with multiple reaction monitoring mode. The proposed method showed good linearity with the correlation coefficients all above 0. 99. The blank samples were spiked at three levels and the average recoveries of target compounds ranged from 68.3% to 127.5% with the RSDs from 0.9% to 15.2%. The limits of detection (LODs) and limits of quantification (LOQs) of the method for the seven target compounds were in the ranges of 0.001-0.090 μg/L and 0.003-0.300 μg/L, respectively. The developed method was successfully applied for the analysis of the UV stabilizers in seawater at Dalian seashores, and some of the benzotriazoles were detected. The method is simple, rapid, environment friendly, highly sensitive and suitable for rapid analysis of benzotriazole UV stabilizers in seawater.