Determination of trace levels of benzophenone-type ultra-violet filters in real matrices by bar adsorptive micro-extraction using selective sorbent phases

• An alternative technique for trace level analysis of UV filters.
• Both activated carbons and polymers can be used for UV filter analysis.
• Validation of a novel methodology to monitor benzophenones-type UV filters.
• Application of the novel analytical approach in several types of real matrices.

Bar adsorptive micro-extraction (BAμE), using selective sorbent phases, followed by liquid desorption in combination with high performance liquid chromatography–diode array detection (BAμE-LD/HPLC–DAD), is proposed for the determination of trace levels of four benzophenone-type UV filters (benzophenone, 2-hydroxy-4-methoxy-benzophenone, 2,4-hydroxybenzophenone and 4-hydroxybenzophenone) in real matrices. By comparing three polymers (P1, P2 and P3) and five activated carbons (AC1, AC2, AC3, AC4 and AC5) phases, P2 (a modified pyrrolidone polymer) and AC4 coatings showed much higher selectivity and capacity through BAμE, where the former offers multiple mechanisms of interaction and faster equilibrium kinetics. Assays performed on 25 mL of ultra-pure water samples spiked at the 8.0 μg/L level, yielded recoveries ranging from 76.6 ± 8.3% to 103.5 ± 6.4% depending on the sorbent phase used (P2 or AC4), under optimized experimental conditions. The analytical performance showed convenient detection limits (0.3–0.5 μg/L) and good linear dynamic ranges (1.0–24.0 μg/L) with remarkable determination coefficients (r2 > 0.9969). Excellent repeatability was also achieved through intraday (RSD < 13.0%) and interday (RSD < 8.9%) experiments. By using the standard addition methodology, the application of the present analytical approach on sea water, wastewater, commercial cosmetic products and urine samples revealed good sensitivity, absence of matrix effects and the occurrence of levels of some benzophenones. The proposed methodology that uses nanostructured particles and operates under the floating sampling technology proved to be a sorption-based static micro-extraction alternative to monitor benzophenone-type UV filters in real matrices. Moreover, is easy to implement, reliable, sensitive, requiring low sample volume and the possibility to choose the most selective sorbent coating according to the target compounds involved.