This standard describes the determination theory of silicon in calcium metal, and specifies the analytical procedure, result calculation and method precision.
It is applicable to the determination of silicon in calcium metal. The determination range is 10~320μg/g with allowable amount of impurities (μg/g): 2 000 of copper, 1 500 of nitrogen, 300 of iron, 700 of aluminum, 300 of manganese, 100 of nickel, 5 000 of magnesium, 50 of arsenic, 50 of phosphorus and 1 000 of chromium.
2 Method summary
In 0.13mol/L hydrochloric acid medium, silicon and ammonium molybdate form silicomolybdic heteropoly acid. Increase the acidity of hydrochloric acid to 1.8mol/L to eliminate the interference of phosphorus. Reduce silicon molybdenum yellow to silicon molybdenum blue by ascorbic acid. Measure the absorbance at spectrophotometer wavelength of 650mn.
3 Reagents
Unless otherwise specified, the reagents used are all analytical reagents, the water used in this method is deionized water or secondary distilled water exchanged by anion-cation exchange resin for the second time, and shall be stored in polyethylene bottles.
3.1 Hydrochloric acid: guaranteed reagent with density of 1.19g/cm3.
3.2 Hydrochloric acid (1+1): prepared with hydrochloric acid (3.1).
3.3 Ammonium molybdate solution 5.0% (m/V).
3.4 Ascorbic acid solution 1.0% (m/V).
3.5 P-nitrophenol ethanol solution 0.1% (m/V).
3.6 Matrix calcium solution: weigh out 12.51g guaranteed reagent of calcium carbonate into a 300mL plastic cup, add 20mL water, slowly add 25.0mL hydrochloric acid (3.1) in fractions, after complete dissolution, transfer the solution to a 100mL volumetric flask, dilute to the scale with water and shake well. 1mL of such solution contains 0.05g calcium.
3.7 Ammonium hydroxide solution: respectively add 100mL water and 100mL guaranteed reagents of ammonium hydroxide into two clean plastic cups, put them into a closed container, and stand for 24h to allow them to be used after diffusion equilibrium.
GB/T 10267.2-1988 The following standards are cited：
GB/T 10267.2-1988 Cited by the following standards：
