Speciation of Chromium in Water Samples with Homogeneous Liquid-Liquid Extraction and Determination by Flame Atomic Absorption Spectrometry

Abstract

A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III) reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion (TBA + )-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a 100 µL micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9. -2 M, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.

Determination of Hexavalent Chromium (Cr(VI)) Concentrations via Ion Chromatography and UV-Vis Spectrophotometry in Samples Collected from Nacogdoches Wastewater Treatment Plant, East Texas (USA)

“…The Cr(VI) concentration obtained from the current study was higher as compared to a study in which river and sea water contained 3.7 and 2.31 ppb [7], respectively (Table 3). Liquid-liquid extraction and flame atomic absorption spectrometry techniques [24] were used for speciation of chromium in tap water and rivers. Rivers contained 4.2 ppb Cr(VI) amounts.…”

Chromium Speciation Using Flow-injection Preconcentration on Xylenol Orange Functionalized Amberlite XAD-16 and Determination in Industrial Water Samples by Flame Atomic Absorption Spectrometry

“…Thus, a pretreatment step is required prior to detection, which can preconcentrate chromium from the matrix selectively. In recent years, several chemical enrichment methods have been employed for the preconcentration of chromium species, such as fractionation, 10 liquid-liquid extraction, 11 dispersive liquid-liquid micro-extraction, 12 solid-phase extraction 13 and coprecipitation.…”

Detection of Cd (II) and Pb (II) by anodic stripping voltammetry using glassy carbon electrodes modified with Ag-Hg and Ag-Bi bimetallic alloyed

“…However, those low levels must be accurately known in order to start a study regarding the extent of a possible contamination process by these two elements as a function of time. Evaluation of electrochemistry-based techniques together with the best way of preconcentration and isolation of heavy metals for their accurate determination have been the goal of several research studies (Zhu et al, 2006;Liang et al, 2005;Abkenar et al,2010;Abkenar et al, 2011;Hosseini et al, 2010;Dahaghin et al, 2017a,b;Bagheri et al, 2012;Huang et al,2014;Huang et al, 2011;Bhatluri et al, 2017). Among the electrochemistry techniques most widely used for Cd and Pb determination, based on their high sensitivity and freedom from matrix effects, anodic re-dissolution voltammetry (ASV) is one of the most convenient.…”