Determination of silicon in chromium carbide by silicon molybdenum blue spectrophotometry with alkali fusion
The accurate determination of silicon content in chromium carbide is of great significance for the quality control of products.The sample was fused with sodium peroxide.After leaching with hot water and acidification,chromium was removed by volatilization with hydrochloric acid.Under certain acidity conditions,silicon could react with ammonium molybdate to form silicon molybdenum yellow.The mix-ture of oxalic acid and sulfuric acid was added to eliminate the interference of phosphorus and iron,and as-corbic acid was added to reduce silicon molybdenum yellow to silicon molybdenum blue for spectrophoto-metric determination at 810 nm.Thus,a method for determination of silicon in chromium carbide was es-tablished by silicon molybdenum blue spectrophotometry with alkali fusion.The results showed that the mass concentration of silicon in range of 0.05-1.20 μg/mL showed good linear relationship with its corre-sponding absorbance with correlation coefficient of 0.999 9.The apparent molar absorptivity was e=22.41 × 103 L·mol-1·cm-1.The limit of detection and limit of quantification for this method were 0.001 7％and 0.005 2％,respectively.The interference tests of coexisting ions showed that the residual chromium in test solution as well as phosphorus and iron in sample had no interference with the determina-tion of silicon.The contents of silicon in three chromium carbide samples were determined according to the proposed method,and the relative standard deviations(RSD,n=9)were between 0.51％and 5.8％.Two chromium carbide samples were conducted for standard addition recovery tests,and the recoveries were be-tween 97％and 102％.
chromium carbidesiliconsilicon molybdenum blue spectrophotometrysodium peroxidealkali fusionchromiumphosphorusiron
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