This standard is applicable to the determination of antimony content in metallic chromium. Determination range: 0.0005～0.0020%. This standard complies with GB 1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". GB/T 4702.9-1985 Chemical Analysis Method for Metallic Chromium Crystal Violet Spectrophotometric Determination of Antimony Content GB/T4702.9-1985 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of chromium metalThe crystal violet spectrophotometric method forthe determination of antimony contentThis standard is applicable to the determination of antimony content in chromium metal. Determination range: 0.0005～0.0020%. This standard complies with GB1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
UDC 669.26 : 543
.42 : 546.86
GB4702.9—85
After the sample is dissolved in dilute sulfuric acid, in a hydrochloric acid medium, stannous chloride is used to reduce tetravalent antimony to trivalent, sodium nitrite oxidizes trivalent antimony to pentavalent, pentavalent antimony forms a green complex with crystal violet, which is extracted with toluene and its absorbance is measured at a wavelength of 540nm on a spectrophotometer. 2 Reagents
2.1 Sulfuric acid (1+4), high-grade pure.
2.2 Hydrochloric acid (specific gravity 1.19), high-grade pure. 2.3 Crystal violet solution (0.2%): Weigh 0.2g crystal violet (high-grade pure), dissolve in 100ml hot water, mix well, filter through 1 cotton wool, and set aside.
2.4 Chlorine saturated solution: weigh 100g urea, dissolve in 100ml hot water, mix well. 2.5 Sodium nitrite solution (10%).
2.6 Tin chloride solution (10%): weigh 10g stannous chloride (superior purity), dissolve in 25ml hydrochloric acid (2.2), dilute to 100ml with water, mix well.
2.7 Methyl methacrylate.
2.8 Antimony standard solution
2.8.1 Weigh 0.0500g metal antimony (99.95% or more), place in a 250ml beaker, add 25ml sulfuric acid (specific gravity 1.84), heat to dissolve, add 25ml sulfuric acid (specific gravity 1.84), transfer the solution to a 500ml volumetric flask, dilute to scale with water, mix well. This solution contains 0.1mg antimony in 1ml.
2.8.2 Take 50.00 ml of antimony standard solution (2.8.1), put it into a 500 ml volumetric flask, dilute it to the mark with hydrochloric acid (1+5), and mix it. This solution contains 0.01 mg of antimony in 1 ml.
3 Instrument
Spectrophotometer.
4 Sample
The sample should all pass through the 1.68 mm sieve.
5 Analysis steps
5.1 Sample quantity
Issued by the National Bureau of Standards on April 15, 1985
Implemented on January 1, 1986
Weigh the sample according to Table 1.
0.0002~ 0.0005
0.0005~0.0020
5.2 Empty test
Carry out the empty test with the sample.
5.3 Determination
GB 4702.9-85
Sample volume,
5.3.1 Place the sample (5.1) in a 250ml beaker, add 20ml sulfuric acid (2.1), heat at low temperature to dissolve, evaporate the solution to 10-12ml and transfer it to a 250ml separatory funnel, wash the beaker with water, and add the washing liquid to the separatory funnel to make the total volume of the solution about 20ml. 5.3.2 Add 20ml hydrochloric acid (2.2) and 3 drops of tin chloride solution (2.6), shake. Add 1ml sodium nitrite solution (2.5), shake for 30s, let stand for 5min, add 40ml water, 0.5ml urea saturated solution (2.4), shake, add 120ml water, 10 drops of crystal violet solution (2.3), add 10ml toluene, shake for 1min. Let stand to separate the layers, and discard the aqueous phase. 5.3.3 Transfer the organic phase into a colorimetric solution of appropriate thickness, and measure its absorbance at a wavelength of 540nm on a spectrophotometer with toluene as reference.
5.3. Subtract the absorbance of the blank test performed with the sample. Find the corresponding antimony amount from the working curve. 5.4 Drawing of the working curve
Pipette 0.00, 0.20, 0.40, 0.60, 0.80, and 1.00 ml of the antimony standard solution (2.8.2) and place them in a set of 250 ml separating funnels respectively. Add water to a solution volume of 20 ml, and proceed as in 5.3.2 and 5.3.3. Subtract the absorbance of the reagent blank, and draw a curve with the antimony amount as the horizontal axis and the absorbance as the vertical axis. 6
Calculation of analysis results
Calculate the antimony content according to the following formula:
Sb(%)=
Wherein: m,——the amount of antimony found from the I curve, g,-the amount of sample, g.
7 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0.0005~0.0010
*0.0010~0.0020bzxz.net
Additional instructions:
GB4702.9—85
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is drafted by Hunan Ferroalloy Factory. From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB582-65 "Metallic Chromium Chemical Analysis Method" will be invalid. 224
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