A simple and green dispersive micro-solid phase extraction method by combined application of graphene oxide and a magnetic ionic liquid for selective determination of inorganic antimony species in water, tea and honey samples

Abstract

A highly selective and efficient method based on the use of graphene oxide (GO) and a magnetic ionic liquid (MIL) for dispersive micro-solid phase extraction (D-μ-SPE) was developed for inorganic Sb speciation analysis. In this work, Sb(III) species was selectively complexed with sodium diethyldithiocarbamate (DDTC) and retained on 3 mg of GO. Afterwards, 40 μL of the MIL trihexyl(tetradecyl)phosphonium hexachlorodysprosiate(III) ([P6,6,6,14]3DyCl6) were added to instantly magnetize the sorbent surface followed by its separation using a magnetic rod. Then, the aqueous phase containing only Sb(V) was directly analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Total Sb concentration was obtained by direct introduction of the sample into ICP-MS instrument. Thus, Sb(III) was calculated based on the difference between the concentrations of total inorganic Sb and Sb(V). Extraction conditions were optimized by a multivariate study yielding a 99.7% extraction efficiency for Sb(III). Limits of detection of 5 ng L−1 for Sb(III) and 3 ng L−1 for Sb(V) and relative standard deviations of 3.2% for Sb(III) and 2.9% for Sb(V) (at 10 μg L−1 Sb(III) and Sb(V), n = 6) were obtained. The calibration linear range was 0.01–80 μg L−1. The proposed method was successfully applied for separation and determination of inorganic Sb species in tap water, tea infusions and honey samples. Furthermore, the greenness of the D-μ-SPE method was assessed by the use of the Analytical GREEnness calculator (AGREE), obtaining a value of 0.61.