Comparison of chromium determinations in environmental and biological samples by neutron activation analysis, atomic absorption and gas chromatography

Highly sensitive procedures for the determination of chromium in bio-environmental samples using neutron activation analysis, atomic absorption and gas chromatography have been developed in this laboratory. In the neutron activation procedure, dried samples are irradiated for up to 100 hours at a neutron flux in excess of 1014 neutrons cm-2s-1 for determinations at the parts per 109 level. Following irradiation, chromium is separated by distillation as chromylchloride and precipitated and counted as BaCrO4. Samples to be analysed by atomic absorption were digested using concentrated nitric acid followed by hydrogen peroxide, and injected into a Perkin Elmer model 2100 graphite furnace. For the gas chromatography determinations an EC detector in pulse mode with linearizer was used to detect chromium trifluoroacetylacetonate following separation on 3% OV-17. Analysis of a round-robin, freeze-dried urine sample by all three methods gave excellent agreement. (author)