RESUMEN
Vacuum-assisted sorbent extraction (VASE) has been applied in combination with gas chromatography-mass spectrometry for the determination of UV filters in water samples. VASE is a variant of headspace extraction which was developed in conjunction with the sorbent pen (SP) technology. This technique combines the advantages of both stir-bar assisted extraction and headspace solid-phase microextraction. The SP traps allowed both reduced pressure in-vial extraction and direct thermal desorption via a unique gas chromatographic injection port. The main parameters that affect the performance of VASE, including both extraction and desorption conditions, were extensively optimized. Under optimum conditions, extraction required 10â¯mL of sample within 40â¯mL vials, pH 3.5, ~30â¯s of air-evacuation, 14â¯h incubation at 70⯰C, stirring at 200â¯rpm, and a final water management step conducted atâ¯~â¯-17⯰C for 15â¯min. Optimal thermal desorption required preheating at 260⯰C for 2â¯min followed by desorption at 300⯰C for 2â¯min. The beneficial effect of reduced-pressure extraction was demonstrated by comparing the UV filter extraction time profiles collected using VASE to an analogous atmospheric pressure procedure, resulting in up to a 3-fold improvement under optimized conditions. The VASE methodology enabled simultaneous extractions using different SPs without compromising the method reproducibility, which increases the overall sample throughput. The method was characterized by low limits of detection, from 0.5 to 80â¯ngâ¯L-1, and adequate reproducibility, with inter-SP and inter-day relative standard deviation lower than 14%. Tap and lake water was successfully analyzed with the proposed methodology, resulting in relative recoveries of spiked samples ranging between 70.0 and 120%.