Simultaneous spectroscopic determination of trace mixed organic acids in aqueous samples using magnetic solid phase extraction coupled with chemometrics method

Abstract

The polyaniline-coated magnetite/silica nanomaterials (Fe₃O₄@SiO₂/PANI) have been synthesized and successfully applied as an effective sorbent for preconcentration of several typical organic acids from environmental water samples. The properties of Fe₃O₄@SiO₂/PANI are characterized by FT-IR and XPS. These magnetic materials can enrich trace organic acids effectively by solid-phase extraction. Three kinds of organic acids, including benzoic acids, phthalic acids, and <em>p</em>-toluene sulfonic acids, are selected as target analytes for magnetic solid phase extraction (MSPE). Various experimental parameters of the MSPE were investigated and optimized. After the desorption process, the elution is detected by the UV-visible spectrophotometer. The spectroscopic data are analyzed through the partial least squares (PLS) method, which facilitate quantitation of mixture from complex data. The enrichment factor of benzoic acids, phthalic acids and <em>p</em>-toluene sulfonic acids reached 19.53, 20.31, and 16.89, respectively. A wide measurement range of 10 μg L^-1 to 50 mg L^-1 is obtained. The LOD is 0.8 μg L^-1. The spiked recoveries in the range of 94%-101% with RSD (<em>n</em>=8) lower than 4%. The results illustrated that the combined approach of MSPE and PLS has great applied potential for a mixture of trace compounds in different fields because of its high efficiency, easy to operate conditions, speediness, and simplicity.