Determination of sunscreen compounds in water samples by silicone rod extraction

Abstract

Silicone rod extraction (SR) is a siloxane-based methodology for the extraction of organic pollutants from aqueous samples with similar principle extraction as the stir bar sorptive extraction (SBSE). In this study the SR was coupled with HPLC-DAD and employed for the extraction and quantification of selected UV filters in water and seawater samples. Chromatographic parameters were optimized as well as the main sorption/desorption conditions for 4-methylbenzylidene camphor (4MBC) and octyl-methoxy cinnamate (OMC) from both river water and seawater samples. After optimization of the proposed method the following variables were selected: 25,0 mL of sample volume, 3 hour extraction, 1250 rpm as stirring velocity and 2 mL methanol as desorption solvent. The recoveries from seawater samples were 76.6% for 4MBC and 85.9% OMC. In river water samples recoveries of 69.8% and 82.4 % for 4MBC and OMC, respectively, were observed when salt was added to the sample. Linear calibration curves were obtained in the corresponding matrix and quantification limits below 1.86 μg L-1 were obtained. A comparison between the proposed method and the SBSE alternative revealed that SR can be use as a reliably and cheap methodology for the determination of sunscreens.