Matrix solid-phase dispersion combined to liquid chromatography–tandem mass spectrometry for the determination of paraben preservatives in mollusks

• Simultaneous determination of 7 parabens and 2 chlorinated derivatives.
• Matrix solid-phase dispersion (MSPD) is a good tool for parabens extraction from mollusks.
• Great recoveries in the 71–117% range were achieved with 3 types of mollusks.
• Detection limits obtained were in the range of 0.04–1.43 ng g−1 dry weight.
• The method has been successfully applied to the analysis of mollusks samples.

A method for the extraction and determination of seven parabens, esters of 4-hydroxybenzoic acid, widely used as preservatives in personal care products, pharmaceuticals, etc., and two chlorinated derivatives (mono- and di-chloro methyl paraben) from mollusk samples was developed by combining matrix solid-phase dispersion (MSPD) and liquid chromatography–tandem mass spectrometry. MSPD parameters, such as solvent, solid support and clean-up sorbent, were optimized. Besides, since blank problems were observed for some parabens, these were investigated and blanks were tackled by precleaning all sorbents prior to use. Under final conditions, 0.5 g of freeze-dried mollusk were dispersed with 1.2 g of silica and packed into a cartridge containing 3 g of C18, as on-line clean-up sorbent. This cartridge was eluted with 10 mL of acetonitrile, evaporated and reconstituted in methanol for analysis. In the validation stage, successful linearity (R2 > 0.999), recoveries (between 71 and 117% for most analytes), precision (RSD lower than 21%) and limits of detection and quantification (LOD and LOQ, lower than 0.4 and 1.4 ng g−1 dry weight respectively) levels were achieved. Finally, the new methodology was applied to mussel, clam and cockle samples. Methyl paraben was above the LOQ in five of the six samples (not found in one clam sample) at concentrations up to 7 ng g−1 dry weight. Ethyl paraben was found above the LOQ in mussel and cockle samples at a concentration level around 0.3 ng g−1. n-Propyl paraben was only above the LOQ in one mussel sample.