The exposure of millions of people to unsafe levels of arsenite (AsIII) and arsenate (AsV) in drinking waters calls for the development of low-cost methods for monitoring these two arsenic species in waters. Herein, in this study a novel dispersive liquid–liquid microextraction based on solidification of floating supramolecular layer for the preconcentration and speciation analysis of inorganic arsenic species has been developed. The method is based on the well-known formation of arsenomolybdate, followed by reduction to heteropoly blue having an absorbance maximum at 815 nm. The blue color was produced from two involved reactions in which the MoO4-2 and AsO4-3 in sample have reacted in acid medium to form arsenomolybdate complex, then the obtained complex was reduced by ascorbic acid liberating the colored molybdenum blue species of heteropoly blue (MoV). A supramolecular solvent made up of reverse micelles of 1dodecanol in tetrahydrofuran (THF) was injected into the aqueous sample solution. Reverse micelle coacervate were produced in situ through self-assembly processes. Vortex-mixed accelerated mass transfer of the target analyte into the supramolecular solvent phase. Various significant parameters affecting the extraction such as type and volume of the extraction solvent, acidity, volume of the disperser solvent, vortex-mixed time and salt concentration were investigated. Under the optimal experimental conditions, detection limit, linear range, and relative standard deviation (RSD) of arsenate were 0.04 ppb, 5-200 ppb and 2.9% (for 50 ppb), respectively. The proposed method was successfully applied to the colorimetric limit for As detection near 5 ppb, which easily meets the requirements imposed by the revised the World Health Organization (WHO) threshold levels for As in drinking water. Keywords Arsenic
