On-line preconcentration using dual mini-columns for the speciation of chromium(III) and chromium(VI) and its application to water samples as studied by inductively coupled plasma-atomic emission spectrometry

Abstract

On-line preconcentration system for the selective, sensitive and simultaneous determination of chromium species was investigated. Dual mini-columns containing chelating resin were utilized for the speciation and preconcentration of Cr (III) and Cr (VI) in water samples. In this system, Cr (III) was collected on first column packed with iminodiacetate resin. Cr (VI) in the effluent from the first column was reduced to Cr (III), which was collected on the second column packed with iminodiacetate resin. Hydroxyammonium chloride was examined as a potential reducing agent for Cr (VI) to Cr (III).The effects of pH, sample flow rate, column length, and interfering ions on the recoveries of Cr (III) were carefully studied. Five milliliters of a sample solution was introduced into the system. The collected species were then sequentially washed by 1M ammonium acetate, eluted by 2M nitric acid and measured by ICP-AES. The detection limit for Cr (III) and Cr (VI) was 0.08 and 0.15 ųg l -1 , respectively. The total analysis time was about 9.4 min. The developed method was successfully applied to the speciation of chromium in river, tap water and wastewater samples with satisfied results.

Speciation of Chromium in Seawater by ICP-AES with Dual Mini-columns Containing Chelating Resin

“…In this system, the conversion of Cr(VI) to Cr(III) was about 73%. 10 After the tube and columns were washed with pure water, the collected chromium species were eluted with 2 M nitric acid. The analytes zones eluted from the columns were introduced to ICP-AES for their measurements.…”

“…This result was also similar to a previously reported result for the speciation of chromium in fresh water. 10 In this dual column system, Cr(VI) was reduced to Cr(III) and collected on the second column. Hydroxyammonium chloride was used as a reducing agent for the conversion of Cr(VI) to Cr(III).…”

Speciation Analysis of Ultratrace Chromium in Water by On-line Reaction/Concentration/Separation Method Using a Cation-Exchange Column

“…The reported speciation methods for chromium usually includes coprecipitation 4 and extraction (solvent extraction or solid-phase sorption) by batch method [5][6][7][8][9][10] and retention of Cr(III) and/or Cr(VI) on a solid phase column [11][12][13][14] followed by instrumental analysis.…”

Simultaneous Determinations of Cr(VI) and Cr(III) by Ion-Exclusion/Cation-Exchange Chromatography with an Unmodified Silica-Gel Column

“…For the determination of Cr(VI) and Cr(III), ion chromatography (IC), spectrophotometry, 4 atomic absorption spectrometry (AAS), [5][6][7] inductively coupled plasma atomic emission spectrometry (ICP-AES) [8][9][10] and inductively coupled plasma mass spectrometry (ICP-MS) [11][12][13] are commonly used. On-line selective and simultaneous determinations for both species have been successfully achieved by chromatographic techniques coupled with AAS, ICP-AES and ICP-MS.…”

“…For the separation of Cr(VI) and Cr(III), mainly solvent extraction, 14 coprecipitation, 15 ion-exchange separation, 16 adsorption on iminodiacetic chelate resins 8,9 and on active alumina 5,10 and electrodeposition 17 are mainly used. Ion chromatography and high-performance liquid chromatography of Cr(VI) and Cr(III) are included in the following techniques: (1) separation of Cr(VI) by an anion-exchange resin and separation of Cr(III) by cation-exchange resins; (2) complexation of Cr(III) with EDTA is used, and this reaction causes formation of the [Cr(III)-EDTA] -anion species.…”