US EPA

1238198 

Journal Article 

Determination of Chromium Oxidation State by X-Ray Fluorescence Spectrometry: Application to Chromium(VI) and Chromium(III) Determination in Occupational Hygiene Samples 

Arber, JM; Urch, DS; West, NG 

1988 

1 

Analyst
ISSN: 0003-2654
EISSN: 1364-5528 

NIOSH/00180998 

113 

5 

779-782 

English 

3414967 

An attempt was made to extend the application of x-ray fluorescence analysis by studying whether chemical effects in the spectra can also be used to determine the chromium(VI) (18540299) content. Toward this end the chromium (7440473) K-spectra x-ray emission lines of various chromium salts and welding fumes were studied and changes in peak, position, and profile observed. Changes were related to oxidation state and ligand environment. While all the chromium K-spectra showed changes in peak position and/or peak profile, their analytical potential for determining the oxidation state of chromium varied considerably. The intensity ratio of Kbeta' to Kbeta1,3 was chosen as the best parameter for determining chromium valency. A series of studies was undertaken including the analysis of mixtures of finely ground chromic-oxide (1308389) (Cr2O3) and potassium-dichromate (7778509) (K2Cr2O7); mixtures of finely ground Cr2O3, K2Cr2O7, and iron-oxide (1317619); authentic welding fume samples; and layers of Cr2O3 and K2Cr2O7 deposited on mixed cellulose ester filters. A good correlation between the intensity ratio used and the proportion of chromium(VI) in the standards was obtained. Analysis of welding fume samples was more problematic due to high background values associated with manganese content. Significantly large errors were associated with the x-ray fluorescence method. It was difficult to measure the accuracy of this method when so few samples were analyzed. The authors conclude that even if the error in determining the chromium(VI) to total chromium ratio is on the order of plus or minus 15 percent, the method is fast and cost effective and may still be useful in occupational hygiene to provide an indication of chromium(VI) levels and for the preliminary sorting of samples. 

DCN-169797; Chemical analysis; Chromium compounds; Metallic fumes; Industrial hygiene; Analytical methods; X ray fluorescence analysis; Air quality measurement; Welders