Spectrographic Determination of Microamount of Calcium in Magnesium with the Transient Discharge Source Unit

概要

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A spectrographic method was studied to determine microamount of calcium in magnesium metal and magnesium alloys, and it was found that calcium in magnesium could be determined by exciting sample solution in a porous-cup electrode with the transient discharge source unit. The results obtained were as follows : (1) In consideration of the viscosity of magnesium solution and the spectral intensity of calcium, 0.5g of sample was dissolved in hydrochloric acid, afterwards diluted to 50 ml. (2) The discharge conditions were E (discharge voltage)=200V, C=18μF, L=30μH, and R=2Ω (3) Exposure was started after 15-sec preliminary discharge, as the discharge was unstable in the biginning of its start. (4) Aluminium, zinc, manganese, iron and zirconium contained in magnesium alloys had no influence on the analytical results of calcium determination, excepting the case when sample contained about 5 per cent of zinc. (5) Samples containing 0.01 to 0.3 per cent of calcium were analysed with Sr II 4215.52A/Ca II 3933.67A as the analytical line pair, the reproducibility being 5 to 7 per cent. (6) It was ascertained that the lower limit of the determination of calcium could be extended down to about 0.001 per cent by using magnesium of higher purity as the base material.
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