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) were 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 were 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 p-toluene sulfonic acids were 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 was detected by UV-Vis spectrophotometer. The spectroscopic data were analyzed through partial least squares (PLS) method which facilitate quantitation of mixture from complex data. The enrichment factor of benzoic acids, phthalic acids and p-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 was obtained. The LOD was 0.8 μg L^-1. The spiked recoveries in the range of  94%-101% with RSD (n=8) lower than 4%. The results illustrated that the combined approach of MSPE and PLS has great applied potential for mixture of trace compounds in different field because of its high efficiency, easy to operate conditions, speediness and simplicity.