Optimization of matrix solid-phase dispersion conditions for UV filters determination in biota samples

摘要

A low solvent consumption method for the determination of eight ultraviolet (UV) filters, displaying low to medium polarities, in freeze-dried samples of marine bivalves and fish is proposed. Matrix solid-phase dispersion (MSPD) and gas chromatography with mass spectrometry (GC-MS) were used as sample preparation and determination techniques, respectively. This work describes the influence of several parameters (type and amount of dispersant and clean-up sorbents, as well as elution solvent) on the yield and the selectivity of the MSPD extraction. Under optimized conditions, samples (0.5 g) were ground with 2g of Florisil in a mortar with a pestle and transferred into a polypropylene syringe, which contained 1 g of C18 as clean-up sorbent. Analytes were eluted with 5mL of acetonitrile. This extract was concentrated to dryness, re-constituted with 1 mL of ethyl acetate and injected in the GC-MS system without any further clean-up. The global average recoveries, measured for three different biota samples, spiked at three different levels (between 50 and 1000ng g~(-1)), ranged from 80% to 101% with associated standard deviations below 10%. The inter-day precision of the method varied from 4% to 15% and the achieved LOQs (defined for a signal to noise ratio of 10) ranged from 4 to 28 ng g~(-1), referred to the freeze-dried matrix. Octocrylene (OCR) was found in some samples of fish and mussels at concentrations between 15 and 20 ng g~(-1), referred to dry mass.