Optimization of the Simultaneous Determination of Cr(III) and Cr(VI) by Ion Chromatography with Chemiluminescence Detection

Abstract

An optimized method for the simultaneous determination of Cr(III) and Cr(VI) in aqueous solutions using ion chromatography with chemiluminescence detection is described. Excellent resolution of the two chromium species was obtained using a single mixed-bed ion-exchange column with continuous elution. After postcolumn reduction of Cr(VI) to Cr(III), the light emitted during the Cr(III)-catalyzed oxidation of luminol with hydrogen peroxide was measured. Parameters affecting the postcolumn reactions such as reductant concentration, reductant mixing, point of luminol introduction, and luminol flow rate were optimized. The calibration curves in the range tested (0.01-50 μg L(-)(1)) were linear, and detection limits of 0.002 μg L(-)(1) for both Cr(III) and Cr(VI) were obtained. The results of the analyses of the water reference materials LGC CRM6010 and NIST SRM1643d with certified chromium values of 49 ± 4 and 18.53 ± 0.20 μg L(-)(1) and found to contain only Cr(III) were 49.2 ± 1.8 and 19.0 ± 1.5 μg L(-)(1), respectively. Values of 10.6 ± 0.5 and 10.1 ± 0.5 μg L(-)(1) were obtained when a simulated water sample containing 10 μg L(-)(1) Cr(III) and Cr(VI) was analyzed.

Ion Chromatography Applications in Wastewater Analysis

“…The UV-VIS detection with post-column reactions is a versatile technique that combines enhanced sensitivity and selectivity for specific applications [26]. The chemiluminescence detection is generally performed in a post-column reaction mode [27]. In ion chromatography, the fluorescence detection is rarely used as a detection method, because only few ions fluoresce [28].…”

Trace Determination of Chromium by Square‐Wave Adsorptive Stripping Voltammetry on Bismuth Film Electrodes

“…Quantification of chromium species can be achieved by optical techniques (such as X-ray fluorescence [1], UVvis spectrophotometry [2] atomic emission spectrometry [3] and, more commonly, atomic absorption sepectrometry [4,5]) as well as chromatograhic methods [6,7]. Among electrochemical techniques, the use of anodic stripping voltammetry (ASV) has been reported but its utility is limited by various interferences and the low electrochemical sensitivity exhibited for chromium species [8].…”

Simultaneous Determination of Copper(II) and Cobalt(II) by Ion Chromatography Coupled with Chemiluminescent Detection

“…To the best of our knowledge, almost all post-column CL assays for trasition-metal ions have been based on a metal-catalyzed reaction of luminol with hydrogen peroxide (H2O2). [8][9][10][11][12] Therefore, it is highly desirable to develop a new CL system in the absence of any special CL reagents for the simultaneous determination of transition-metal ions.…”

“…To the best of our knowledge, almost all post-column CL assays for trasition-metal ions have been based on a metal-catalyzed reaction of luminol with hydrogen peroxide (H2O2). [8][9][10][11][12] Therefore, it is highly desirable to develop a new CL system in the absence of any special CL reagents for the simultaneous determination of transition-metal ions.The decomposition of H2O2 catalyzed by transition-metal ions or their complexes in homogeneous and heterogeneous systems has been extensively studied, and different mechanisms have been suggested for these reactions. [13][14][15][16][17] It is well known that the decomposition of H2O2 in the presence of transition-metal ions produces singlet oxygen ( 1 O2), which is a light-emitting species.…”