抄録
Phosphorous in ferrochromium was determined without separation of chromium by the molybdenum blue method. Following the preceding report on effects of reagents on the color development, effects of chromium and a few of salts or acids on the color development were further investigated. Effects of co-existing elements, salts and acids, were mainly to retard the rate of color development. Above all, chromium (III) had a remarkable effect. As a result of experiments on the color development in detail, it was found that the effect of chromium (III) could be eliminated when the concentration of reagents was increased and the digestion time was prolonged. In like manner, the effect of acids could also be eliminated. Chromium (III) showed almost no absorption at the wavelength of over 750 mμ.
In this experiment, a reagent mixture solution of 12 mL of 2% ammonium molybdate, 13 mL of 10N sulfuric acid and 5 mL of o.15% hydrazine sulfate was used, and digested at the total volume of about 90 mL for 30 minutes. Chromium (III), amounting up to 150 mg, had no effect in this condition.
This wethod was expedient and its accuracy was equivalent to or higher than that when chromium was separated.
