Abstract
The reaction of chlorochromate anion (CrO3Cl−) with rhodamine 6G hydrochloride dye (RG+) results in the formation of complex ion associate [RG+·CrO3Cl−] in non-aqueous medium. This study aimed to use t-octylphenoxypolyethoxyethanol polymer (Triton X-100) in [RG+·CrO3Cl]org extraction system to enhance the sensitivity of Cr(VI) under the optimized conditions. The produced highly electron deficient system in the binary complex ion associate [RG+·CrO3Cl] of Cr(VI) transforms into an adduct [(CrO3Cl−·RG+)·TX-100·nS]org in the presence of Triton X-100 (TX-100). This transformation enhanced the analytical response of the produced adduct specie in the organic phase by over 75%. The adduct formation via ether oxygen of TX-100 and the possible existence of H-bonding between NH of RG+ and ether oxygen of TX-100 are directly related to the increase in the molar absorptivity and this phenomenon was monitored by UV–Vis spectrophotometric measurement at λmax=534nm. The current study discusses the role of different surfactants and its influence on the extraction of Cr(III) & Cr(VI) species. A detailed proposed mechanism, structure, stoichiometry, and extraction equilibria for the produced adduct is presented. Cr(III) species after oxidation with H2O2 in KOH media were also determined by the proposed procedure. At optimal conditions, the method exhibited a wide linear range 0.0245–1.5μgmL−1 with detection and quantification limits of 0.0073μgmL−1 and 0.025μgmL−1, respectively. This enhancement principle in the extraction systems could be extended to other class of surfactants and/or nano materials.
[Display omitted]
•Simple, fast and sensitive methodology for speciation of Cr(III) and Cr(VI) species.•The role of surfactant types in extraction of chromium has been discussed.•Simple amplification strategy with complete proposed mechanism is discussed.•The figures of merits are comparable to the modern microextraction techniques.•Future trends: The need for using new materials for different analytes in liquid extractions.