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

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-mu-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 mu L of the MIL trihexyl(tetradecyl)phosphonium hexachlorodysprosiate(III) ([P-6,P-6,P-6,P-14](3)DyCl6) 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 mu g L-1 Sb(III) and Sb(V), n = 6) were obtained. The calibration linear range was 0.01-80 mu g 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-mu-SPE method was assessed by the use of the Analytical GREEnness calculator (AGREE), obtaining a value of 0.61.

Automated summary

A highly selective and efficient method using graphene oxide (GO) and a magnetic ionic liquid (MIL) for dispersive micro-solid phase extraction (D-mu-SPE) of inorganic Sb speciation analysis was developed. Sb(III) was complexed with sodium diethyldithiocarbamate (DDTC) and retained on GO, followed by magnetization of the sorbent surface with MIL and separation using a magnetic rod. The aqueous phase containing only Sb(V) was directly analyzed by ICP-MS. The method showed high extraction efficiency, low limits of detection, and good precision for Sb(III) and Sb(V) determination. It was successfully applied in the analysis of inorganic Sb species in tap water, tea infusions, and honey samples. The method also demonstrated good environmental performance according to the Analytical GREEnness calculator (AGREE) with a value of 0.61.