Easy determination of benzophenone and its derivatives in sunscreen samples by direct-immersion solid-phase microextraction and gas chromatography-mass spectrometry.

Benzophenones (BPs) absorb different sun radiation wavelengths, making them effective UVA and UVB filters, widely used in industry. In Europe, sunscreen products contain regulated amounts (6 % w/w) of benzophenone-3 (BP-3), usually combined with other filters like octocrylene. BPs are mutagens in UV radiation, and octocrylene may degrade into BPs, making their monitoring crucial. The present manuscript proposed a novel procedure based on liquid-liquid extraction followed by direct-immersion solid-phase microextraction (LLE-DI-SPME) to isolate and determine 10 BPs in sunscreen lotions with potential results. Parameters like extraction solvent, pH, adsorption, desorption time, stirring, sating effect, and presence of organic solvents were optimized and compared with different SPME fibers, being polyacrylate (PA) fiber the most effective. Detection and quantification were performed by gas chromatography-mass-spectrometry. Analytical parameters as limits of detection were 0.05-0.10 µg kg-1, while the linear range was 0.16 up to 2000 µg kg-1. In terms of recovery, the method ranged from 83 % to 103 %; the precision of the method was good in terms of relative standard deviation (RSD) from 3.2 % to 18.7 % and without a remarkable matrix effect (-15.06-8.45 %). Despite the complexity of the samples and the difficulty posed by the DI-SPME technique, the method proved robust. The proposed method successfully detected 10 BPs in 6 different sunscreen lotions. The total presence of BPs in sunscreens ranged from 165 to 931 mg kg-1, with BP-3 detected in all samples from 4.2 to 740 mg kg-1.