Preparation of a porous aromatic framework via the Chan-Lam reaction: a coating for solid-phase microextraction of antioxidants and preservatives

The Chan-Lam reaction was applied to the preparation of a porous aromatic framework (PAF) at room temperature in air without employing expensive noble metal catalysts. The PAF is shown to be a viable sorbent for use in solid-phase microextraction of antioxidants and preservatives as contained in cosmetics. The material was characterized by FT-IR, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. Effects of various experimental parameters on the extraction efficiency were investigated. The analytes were extracted by using a fiber coated with the PAF. Following extraction, the fiber was directly inserted into a GC analyzer with flame ionization detection. Specifically, the following antioxidants and preservatives were extracted and detected: 2-tert-butyl-4-methoxyphenol (BHA), 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT), methylparaben (MP), and propylparaben (PP). Under the optimum experimental conditions, the method has a low limit of detection (0.12-0.22 mu g L-1 for antioxidants and 0.19-0.30 mu g L-1 for preservatives) and a linear response in the 0.02 to 500 mg L-1 for concentration range. Relatives standard deviations (RSDs) for one fiber ranged from 1.2% to 7.2% (n = 6) while those for three different fibers (n = 3) were in the range between 4.3% and 11.0%. The fiber was successfully employed to the determination of antioxidants and preservatives in cosmetic samples with recoveries of 81.5%-110.2%.