chromium(III) up to 100 ng mL−1, and for chromium(VI) up to 200 ng mL−1) were obtained, using the “fixed time” method with detection limits of 4.9 ng mL−1 and 3.8 ng mL−1, respectively. The results suggest that at the reaction conditions chromium(VI) is reduced and chromium(III) is oxidized to an intermediate oxidation state and the catalytic action of chromium is due to the formation of an act...

The appearance of kits for the determination of micro amounts of calcium stimulated our interest in the use of Eriochrome Blue SE for this analysis. A study of spectrophotometric curves indicates that, at pH values above 13.7, calcium will complex and cause a change of dye absorbance while magnesium does not complex with the dye. A differential spectrophotometric technic is described in this pa...

Gasometric methods for estimating blood oxygen are time-consuming. This consideration often limits the number of observations which can be made in the course of experiments requiring oxygen determinations. In many cases it is an arteriovenous difference which is particularly desired, as in the measurement of cardiac output by the Fick principle, or the estimation of oxygen consumption by human ...