Determination of parabens in waters by magnetically confined hydrophobic nanoparticle microextraction coupled to gas chromatography/mass spectrometry

In this article, magnetically confined hydrophobic nanoparticle microextraction is applied for the analysis of parabens in water samples by gas chromatography (GC)-mass spectrometry (MS). The hydrophobic magnetic nanoparticles (MNPs) are confined in a device by means of a mini-magnet which also allows the stirring of the unit. A thin layer of MNPs, which presents an optimal surface to volume ratio, is the responsible of the analytes extraction. Although the superficial area of the layer is lower than the potential one obtained with a perfect dispersion of the MNPs, the latter approach is hard to be performed with highly hydrophobic MNPs and therefore the proposed configuration is more useful from a practical point of view. This fact, together with the inherent stirring of the unit, enhances the kinetic extraction and therefore the sensitivity of the procedure compared to conventional dispersion conditions. The most influential extraction parameters were evaluated, including the pH and ionic strength of the sample, the stirring rate, the extraction time, the amounts of MNPs, the volume of sample and the elution conditions. Under the most favorable extraction parameters, the method showed good linearity, repeatability (relative standard deviation below 7.1%, n = 7) and sensitivity in the ng per liter range. The proposed method was demonstrated to be a simple, fast and efficient method for the analysis of parabens in sea and swimming pool water samples.