99.5% yellow tungsten oxide is a yellow powder with high purity. The determination process of Si in the yellow tungsten oxide is available by silicon molybdenum blue spectrophotometry method, which is easy to operate by dissolving yellow tungsten oxide with NaOH solution and complexing tungsten with citric acid. The measurement range of ωSi is from 0.0004% to 0.016%, the recovery rate is at the range of 95.71%~118%, and the relative standard deviation is less than 14.32%.
Silicon Molybdenum Blue Spectrophotometry Method for Testing Trace Amount of Si in Yellow Tungsten Oxide
1. Weigh 1.000g sample, placed in a graduated plastic bottle, add in 30mL NaOH solution, cover the cap, heated in 90°C hot water for 30min, shake from time to time until the solution is clear and diluted with water to 50mL.
2. Take 5mL test solution in 25mL colorimetric cylinder, add in 1 drop of p-Nitrophenol indicator, drop in sulfuric acid (0.5mol/L) to colorless; add in 1mL sulfuric acid, diluted with water to 10mL; add ammonium molybdate (100g/L) 1mL, let sit for 20min; add in 3mL citric acid (50g/L), shake up, add in 2mL hay sulphur mixed acid, 1mL 1-amino-2-naphthol-4-sulfonic acid, shake well and let sit for 10min.
3. Then, absorbance is measured at a wavelength of 680nm by using a 1 cm cuvette with a reagent blank as a reference.
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