A simple capture-release strategy based on an instantly formed mixed metal hydroxide sorbent for determination of salicylic acid in cosmetics

We present a simple eco-friendly extraction-release strategy for enhancing the assessment of salicylic acid (SA) in cosmetic samples. Given that the extraction and the formation of mixed metal hydroxides (MMHs) acting as sorbent occurred at the same time, the in situ solid phase extraction (is-SPE) of SA was achieved by mixing magnesium and aluminium ions in an alkaline sample solution. After the is-SPE, the MMHs precipitates were isolated by centrifugation and dissolved completely in sulfuric acid. Subsequently, the released SA was quantified by spectrophotometry at 237 nm. The is-SPE parameters including the amount of hydroxide ions, amount of metal ions, extraction time, and centrifugation time were studied thoroughly. Under the optimized conditions, this method provided the linear range of 0.15-2 mg L-1 with the relative standard deviations of less than 7.20% and the limit of detection of 45 mu g L-1. In addition, the proposed method was successfully applied for SA analysis in toner, foam, and serum samples with reasonable relative recoveries in the range of 76.3-100.3%. This method eliminated the use of organic solvents and avoided the synthesis step of sorbents as well as their characterization, thus saving time, chemicals, and energy.