Exploiting Cork as Biosorbent Extraction Phase for Solid-Phase Microextraction to Determine 3-(4-Methylbenzylidene)camphor and 2-Ethylhexyl 4-(Dimethylamino)benzoate in River Water by Gas Chromatography-Mass Spectrometry

In this study, a method for the determination of 3-(4-methylbenzylidene)camphor (4-MBC) and 2-ethylhexyl 4-(dimethylamino)benzoate (OD-PABA) in river water samples employing cork as the SPME (solid-phase microextraction) fiber was developed. The extraction parameters optimized were pH, ionic strength and extraction time and temperature. For the extraction step, the sample pH was studied in univariate experiments while the extraction time, temperature and ionic strength were evaluated using a central composite design. The optimal extraction conditions were sample pH 4.0, extraction time 70 min, sample temperature 80 °C and sodium chloride concentration 6% (m v-1). The limits of quantification for 4-MBC and OD-PABA were 0.1 and 0.01 µg L-1, respectively. The linear correlation coefficients were greater than 0.97 for both analytes and the developed method showed recovery values between 67 and 107%. In an evaluation of the fiber-to-fiber reproducibility (fibers produced by different analysts), the relative standard deviation (RSD) was lower than 11% (n = 6).