Arsenic speciation analysis in mono-varietal wines by on-line ionic liquid-based dispersive liquid-liquid microextraction

Abstract

A highly efficient separation and pre-concentration method for arsenic species determination, based on ionic liquid (IL) dispersive microextraction technique implemented in a flow analysis system, is proposed. Arsenite species [As(III)] were selectively separated by chelation with sodium diethyldithiocarbamate (DDTC), followed by dispersion with 40 mg of 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) IL. After analyte extraction, retention and separation of the IL phase was achieved with a packed microcolumn, which was subsequently eluted into a graphite tube for determination of As(III) by electrothermal atomic absorption spectrometry (ETAAS). Concentration of As(V) was deduced by the difference between total inorganic arsenic and As(III). Thus, determination of total arsenic was performed by previous degradation of organo-arsenic species, followed by a reduction. Under optimal conditions, As(III) extraction efficiency was 100% and a sensitivity enhancement factor of 46 was obtained with only 4.0 ml of sample The method was successfully applied for arsenic speciation studies in mono-varietal wines.