A speciation method for Cr(III) and Cr(VI) by on-line solid-phase extraction using a flow-injection system with FAAS has been proposed. The Cr(III) was selectively retained at pH 5 on the AXAD16-XO chelating resin and was eluted using 0.5 mol L -1 HNO3. The preconcentration factor and the detection limit (3σ) of 73 and 0.11 μg L -1 , respectively, were obtained for a 120-s preconcentration time. The precision (%RSD) at the 100 μg L -1 level was 1.08%. The linearity for Cr(III) measurements was up to 600 μg L -1 . The total chromium was determined by reducing Cr(VI) to Cr(III) using hydroxylamine hydrochloride, and the Cr(VI) concentration was obtained by subtraction from the total chromium concentration. The effect of interfering ions was examined towards the selectivity of the proposed system for Cr(III). Spike recovery studies in industrial water samples were carried out using standard Cr(III) and Cr(VI) solutions traceable to NIST. The proposed method was validated using SRM 1643e (Trace Elements in Water) supplied by NIST, USA.

An online preconcentration system based on solid-phase extraction was developed for speciation and determinations of Cr in industrial water samples using flame atomic absorption spectrometry. A minicolumn packed with Amberlite XAD-16 loaded with salicylic acid was used to preconcentrate chromium species. All flow and chemical parameters that influence sorption were studied. The preconcentration factor and detection limit for the preconcentration time of 120 s were 79 and 0.10 μg L -1 , respectively. The concentration of Cr(VI) species was calculated by the difference of the total Cr and Cr(III). The relative standard deviation (RSD) (five replicate of measurements) for 50 and 100 μg L -1 Cr(III) solution was 1.2 and 1.0% respectively. The accuracy of the method was verified by analyzing a standard reference material (NIST SRM 1640a, trace elements in natural water). The proposed preconcentration method was successfully applied to the determination of Cr species in industrial water samples with satisfactory results.

Preconcentrative speciation of chromium in industrial water samples using a flow injection – FAAS system with a synthesized chelating resin in a minicolumn.

An online flow injection preconcentration system for speciation of Cr(iii) and Cr(vi) based on the combination of solid phase extraction (SPE) and flame atomic absorption spectrometry (FAAS) has been described.

No abstract

No abstract

Persistent industrial activities have led to an increase in the chromium content in environmental water bodies. The accurate quantification of trace chromium species such as Cr(III) and Cr(VI) is crucial as Cr(VI) can exhibit toxicity even at sub‐ppb levels. We report herein a comparative chromium speciation study using two chemically functionalized nanoadsorbents and determination with hyphenated flow injection‐flame atomic absorption spectrometry (FI‐FAAS). The most efficient preconcentration performance was obtained by optimizing the chemical and hydrodynamic parameters. Cr(VI) concentration was ascertained by the reduction to Cr(III) as the nanoadsorbents were selective for Cr(III) adsorption only; thus, speciation was achieved. The method was selective for Cr(III) in the presence of interfering matrix components. Preconcentration factor >90 and detection limit <0.11 μg L−1 were obtained for both the nanoadsorbents (%RSD∼1.0 %). The adsorption capacity of CNT‐TYR and CNT‐ASA was found to be 42.0 and 43.2 mg g−1, respectively. The application of the proposed method to contaminated water samples gave recoveries >95 %. The accuracy of the method was verified using NIST SRM 1640a.

Due to unchecked disposal of industrial wastes into surrounding areas, the pollution of water bodies with heavy metal toxicants has become an environmental menace. The toxicity of chromium species depends on its oxidation states, and thus regular monitoring of environmental water sources vulnerable to pollution is a must. In this regard, an on-line method for chromium speciation and determination using FAAS has been proposed. The flowinjection preconcentration mini-column containing polytetrafluoroethylene beads was used as the solid phase extractant, and chromium speciation was done by complexing Cr(III) and Cr(VI) with thiosemicarbazide chelating agent. The figures of merit for Cr(III) and Cr(VI) obtained were 61 and 56 (preconcentration factors); 0.13 and 0.14 lg L -1 (detection limits); 1.6 and 1.3% (R.S.D.). The optimized method for chromium speciation was successfully applied to industrial and Yamuna River water samples. The method validation was carried out using SRM 1640a (Trace Elements in Natural Water, NIST), and recovery [ 95% was obtained.