GB/T 4375.7-1984 Chemical analysis of gallium - Molybdenum blue photometric method for the determination of silicon content

GB/T 4375.7-1984 Chemical analysis method for gallium - Determination of silicon content by molybdenum blue photometry GB/T4375.7-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of gallium The molybdenum blue photometric method for the determination of silicon content
Methods for chemical analysis of gallium The molybdenum blue photometric method for the determination of silicon content This standard applies to the determination of silicon in gallium. Determination range: 0.000050～0.00060%. UDC 669.871 : 543
.42 :546.28
GB 4375.7-84
This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
The sample is dissolved in hydrochloric acid. At 0.4N hydrochloric acid acidity, silicon reacts with ammonium tantalum to form silicomolybdenum yellow heteropoly acid. Use tartaric acid to eliminate possible interference from phosphorus and ions, and use 1-hydrogen-2-naphthol-4-sulfonic acid to reduce silicon molybdenum yellow to silicon potassium blue. Extract with n-pentanol and measure its absorbance at a wavelength of 800nm ​​on a spectrophotometer. 2 Reagents
2.1 Hydrochloric acid (6N): Prepare with hydrochloric acid (specific gravity 1.19) after sub-boiling distillation. 2.2 Hydrochloric acid (3N): Prepare with hydrochloric acid (2.1). 2.3 Sulfuric acid (1+1).
n-pentanol: Purify by distillation at 137-139°C. Before use, use 2.9N sulfuric acid [100ml containing 3ml reducing agent solution (2.8)] to saturate potassium permanganate solution (0.1%).
Ammonium vanadate (high purity) solution (10%).
Tartaric acid (high purity) solution (20%).
2.8 Reducing agent solution (0.2%): Weigh 0.2g 1-amino-2-naphthol-4-sulfonic acid and dissolve it in 100ml 4% sodium sulfite solution.
2.9 Deionized water: conductivity greater than 10MS2. 2.10 Matrix solution: Weigh 3.000g (high purity) and divide it equally into 3 platinum crucibles, add 7.5-8.0ml hydrochloric acid (2.1) respectively, cover with platinum cover, heat to 75-80℃ to dissolve, evaporate to 1/2 of the original volume, remove, cool and combine the solutions, dilute with water to 60ml, mix well. This solution contains 0.05g gallium in 1ml. 2.11 Silicon standard stock solution: Weigh 2.139g silicon oxide (99.9% or more), place in a platinum crucible, add 10g sodium carbonate and potassium carbonate mixed flux (2+1), mix, melt on a blowtorch until the solution is clear, burn for 10 minutes, cool and leach with hot water, heat until the solution is clear. Cool, transfer to a 1000ml volumetric flask, dilute to scale with water, mix, and immediately transfer to a plastic bottle. This solution contains 1.0mg silicon per ml. www.bzxz.net
2.12 Silicon standard solution: Transfer 25.00ml silicon standard stock solution (2.11), place in a 250ml volumetric flask, dilute to scale with water, mix, and immediately transfer to a plastic bottle. This solution contains 100μg silicon per ml. 2.13 Silicon standard solution: Transfer 5.00ml silicon standard solution (2.12), place in a 100ml volumetric flask, dilute to scale with water, mix, and immediately transfer to a plastic bottle. This solution contains 5μg silicon in 1ml. Issued by the National Bureau of Standards on April 30, 1984
Implemented on April 1, 1985
3 Apparatus and instruments
3.1 Spectrophotometer.
3.2 Crucible.
3.3 Centrifuge.
4 Analysis steps
4.1 Determination quantity
GB4375.7—84
Weigh 3 samples for determination and take the average value. 4.2 Sample quantity
Weigh 0.5000g sample.
4.3 Air self-test
Carry out air self-test with the sample.
4.4 Determination
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4.4.1 Place the sample (4.2) in a 120ml crucible, add 3.5ml hydrochloric acid (2.1), cover with a platinum cap, heat at 70±2°C for 40min, remove the cap, continue heating [if it is not completely dissolved, add 3 to 8 drops of hydrochloric acid (2.1), evaporate to a volume of about 2ml, and cool. 4.4.2 Pour the solution (4.4.1) into a polyethylene bottle containing 5.3ml hydrochloric acid (2.2), wash the crucible with water, add the washing liquid into the polyethylene bottle, and dilute with water to 25ml, add potassium permanganate solution (2.5) dropwise until the solution turns a steady red, and dilute with water to 30ml.
4.4.3 Add 10ml of ammonium acid solution (2.6), place it at 28±2°C for 15min, then add 1ml of tartaric acid solution (2.7), 8ml of sulfuric acid (2.3), and 1.5ml of reducing agent solution (2.8). Mix each reagent and place it for 15min. 4.4.4 Transfer the solution (4.4.3) to a 100ml separatory funnel, add 10.00ml of n-pentanol (2.4), shake for 1min, let stand to separate the layers, and discard the aqueous phase. Transfer the organic phase to a 10ml centrifuge tube and centrifuge. 4.4.5 Transfer part of the solution (4.4.4) to a 3cm colorimetric III, use the blank sample as a reference, and measure its absorbance at a wavelength of 800nm ​​on a spectrophotometer at not less than 25°C. Find the corresponding silicon content from the curve drawn in 1. 4.5 [Drawing the curve
4.5.1 Take 0, 0.05, 0.10, 0.20, 0.40, 0.60 ml of silicon standard solution (2.13) and place them in a set of 50 ml polyethylene bottles containing 10 ml of matrix solution (2.10), add water to 20 ml, add 5.3 ml of hydrochloric acid (2.2), add potassium permanganate solution (2.5) dropwise until the solution turns a stable red color, and dilute with water to 30 ml. The following is carried out according to 4.4.3 and 4.4.4. 4.5.2 Take part of the solution (4.5.1) and place it in a 3 cm colorimetric tube. Using the compensation solution as a reference, measure its absorbance at a wavelength of 800 nm on a spectrophotometer. Draw a curve with silicon content as the horizontal axis and absorbance as the vertical axis. Calculation of analysis results
Calculate the percentage of silicon according to the following formula:
Si (%) =
Formula: m, silicon content found from the L curve, ug; sample volume, g.
6 Allowable difference
mo ×106× 100
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. 296
Additional instructions:
0. 00005 ~ 0. 00020
:-0. 00020 ~0.00060
GB4375.7—84
This standard was proposed by China Nonferrous Metals Corporation. This standard was drafted by the Nonferrous Metals Research Institute of China Nonferrous Metals Corporation. The main drafter of this standard was He Liying.
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