US EPA

1238059 

Journal Article 

Gel Chromatographic Behaviour Of Trace Amounts Of Chromium(VI) And Hydrolysed Chromium(III) In Aqueous Solution 

Osaki, S; Osaki, T; Setoyama, M; Takashima, Y 

1983 

1 

Journal of Chromatography
ISSN: 0021-9673 

NIOSH/00141619 

257 

1 

180-184 

The gel chromatographic behavior of trace amounts of chromate (11104599) and hydrolyzed chromium(III) (16065831) species in aqueous solutions was investigated. Sample solutions with 0.00000002 molar chromium(III) concentrations, radiolabeled by adding chromium-51 (14392020) as sodium-chromate, (7775113) were prepared. A glass column, 450 by 19 millimeters, was packed with a slurry of Sephadex G-50 dry gel which was swelled in distilled water for 24 hours. Radioactivity in 5 milliliter aliquots of the sample solutions was counted using liquid scintillation counting. Aliquots were stored in polyethylene bottles for 1 and 7 days before chromatographic analysis or analyzed immediately. The effects of pH shifts from 1.42 to 12.63 on hydrolyzed chromium(III) solutions were also examined. A sharp peak assigned to chromate ions was obtained from gel chromatography of chromium(VI) (18540299) in 0.01 or 0.05 molar (M) concentrations of sodium-chloride (pH 7). The peak for chromium(VI) in 0.005M concentrations of sodium-chloride was slightly shifted and that for chromium(VI) in distilled water was further shifted, possibly due to the ion exchange effect of the gel. At pH 1.42, 100 percent of chromium(III) eluted in the fraction of lower molecular weight (fraction 1). Up to pH 7.75 this fraction decreased, while the eluted fraction of higher molecular weight (fraction 2) increased as did the quantity of chromium(III) adsorbed on to the gel (fraction 3). Chromium(III) was also partially adsorbed on to the polyethylene bottle during storage (fraction 4). The peaks of fraction 1 were eluted in the same fraction number to the chromate ions. The peaks of fraction 2 were eluted at the void volume of the column. The authors conclude that the chromium(III) species in the samples may consist of aqueous ions, or the latent hydroxide. The chromium concentrations of fractions 1, 2, and 3 correlate with neither the pH of the sample solutions nor the storage times. 

DCN-129172; Chromatographic analysis; Physical properties; Chemical properties; Metallic ions; Chromium salts; Trace analysis; Quantitative analysis; Qualitative analysis; Water analysis; Acidity; Scintillation counters