Chromium, ETAA

The sequential extraction of chromium from soils has been studied [89]. A three-step sequential extraction scheme has been proposed using acetic acid, hydroxylamine hydrochloride and ammonium acetate as extracting agents. Steps 1 and 2 were measured by electrothermal atomic absorption spectrometry (ETAAS). Step 3 was measured by flame atomic absorption spectrometry. Interfering effects when measuring chromium in soils were circumvented through the use of a 1% 5-hydroxyquinoline suppressor agent. 

Work Item F determination of lead, cadmium, chromium and molybdenum by ETAAS after pressure digestion. 

A systematic difference was observed between high chromium values obtained by NAA techniques and ICP-MS and ICP-AES data. It was suspected that in some cases the digestion method used was not sufficiently strong to decompose the matrix the addition of HF after HNO3 decomposition is a prerequisite. The main problem was, however, related to strong interferences occurring at mass 52 with argon. As already mentioned for arsenic, ICP-MS and ICP-AES were not considered to be suitable for certification and the different sets were consequently withdrawn ETAAS is clearly more reliable for chromium determination in comparison to ICP-MS. 

Chromium. Some results in step 1 were rejected as they were below the limits of determination. Other sets of results suffered from contamination problems (high results with high standard deviations) and were consequently withdrawn. The remaining sets in this step ranged from 0.72 to 2.00 mg kg (3 ETAAS and 4 ICP). Improvement was considered to be necessary before contemplating certification. 

There are three techniques used for the determination of chromium in tissues and body fluids (1) neutron activation analysis (NAA), (2) isotope dilution mass spectrometry (IDMS), and (3) electrothermal atomic absorption spectroscopy (ETAAS). 

Urine chromium determined by ETAAS with Zeeman background correction and standard addition procedure outlined in this section has a reported detection limit of 0.1 p.g/liter. This is an outline of the method of Fleischer [46]. The reference provides detailed directions for this analysis. 

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