Fabrication Of SPME Fiber Through UV-induced Polymerization For Determination Of Preservatives In Cosmetics

Concerns about the safety of daily used cosmetic products are growing in recentyears, and it is important to monitor the usage of commonly additives such aspreservatives in cosmetics. Solid-phase microextraction (SPME), introduced in theearly1990s, is regarded as a rapid, simple and sensitive pretreatment method. Thedevelopment of SPME has provided a valuable alternative to other samplepretreatment methods. Herein, we aimed to establish a rapid and efficient method forthe determination of preservatives in cosmetics by using SPME as samplepretreatment method, employing ultra high-speed liquid chromatography. Fornon-volatile compounds, direct-SPME procedure is often selected. Since non-volatilecould be a criteria for a large range of additives used in daily products, we aimed todevelop a facile and inexpensive method for the preparation of SPME fiber coatingwith desirable properties such as good solvent-resistant property used fordirect-SPME.The fabrication of a SPME fiber through UV-induced polymerization ofpoly(ethylene glycol) diacrylate (PEG-DA) is presented in this work. The fibersurface modification with3-(trichlorosily)propyl methacrylate (TPM) was introduced,and then PEG-DA was crosslinked around the fiber in the presence of the photorinitiator2-hydroxy-2-methyl-propiophenone under UV light, generating a solidpolymer as fiber coating. The fabricated SPME fibers showed much bettersolvent-resistant property than those without the surface modification step. Thesurface of the prepared fiber was characterized by scanning electron microscope andan inverted fluorescence microscope. The fiber surface was found to be homogeneouswith thickness of around80μm. Wrinkle structures was presented on the fiber surface,which led to an increase of the surface area and good extraction efficiency. Since thethickness of the fiber coating prepared can be measured simply and accurately by theintroduction of an inverted fluorescence microscope, a further election of preparedfibers can be progressed to obtain a better reproducibility. Sample pretreatment method for parabens (including methylparaben,ethylparaben, propylparaben and benzylparaben) from cosmetic products wasestablished by using the fabricated SPME fiber. The analysis was performed on anultra high-speed liquid chromatography with diode array detector. The extractionefficiency of the prepared fibers using PEG-DA molecules of different molecularweights was investigated and extraction parameters were optimized. The optimizedSPME method supported a wide linear range of0.50-160μg/mL with correlationcoefficients greater than0.995. Moreover, the prepared fibers exhibited goodrepeatability (for one fiber) and reproducibility (fiber-to-fiber) with RSDs of5.4%and6.9%, respectively. The maximum adsorption capacity was determined to be540μg, and the detection limits for parabens were in the range of0.12-0.15μg/mL (S/N=3). The developed method was successfully applied for analyses of parabens incommercial cosmetic products with different natures with good recoveries.The presented SPME fiber fabrication method was stable and reliable with goodrepeatability and reproducibility, which could be applied for rapid analyses ofpreservatives in cosmetic products.