This standard is applicable to the determination of copper content in metallic chromium. GB/T 4702.10-1985 Chemical analysis method for metallic chromium - Determination of copper content by copper reagent spectrophotometry GB/T4702.10-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of chromium metalThe cupral spectrophotometric method for thedetermination of copper contentThis standard is applicable to the determination of copper content in chromium metal. Determination range: 0.010~0.100%. This standard complies with GB1467--78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". Method summary
UDC 669.26 : 543
42 : 546.56
GB 4702.10-85
The sample is dissolved in dilute sulfuric acid, and EDTA and citric acid are used to mask the elements such as iron, aluminum, chromium, and manganese. The solution is adjusted to pH 9, and the copper reagent forms a stable yellow complex with copper ions. It is extracted with chloroform and its absorbance is measured at a wavelength of 430nm on a spectrophotometer. 2 Reagents
2.1 Sulfuric acid (1+2).
2.2 Ammonium hydroxide (specific gravity 0.90).
2.3 Chloroform.
2.4 Sodium diethyldithiocarbamate (copper reagent) solution (0.1%). Prepare when using. 2.5 Ethylenediaminetetraacetic acid-sodium (EDTA) solution (1.5%). 2.6 Citric acid solution (50%): Take 100ml 50% citric acid solution, place it in a 250ml separatory funnel, add 2 drops of phenolphthalein ethanol solution (0.1%), neutralize the solution with ammonium hydroxide until it turns red and add 6 drops in excess, add 5ml copper reagent solution and 25ml chloroform, and shake for 1min. After standing and stratification, discard the organic phase, add 10ml chloroform to the water layer, repeat the extraction until the organic phase is colorless, discard the organic phase, and put the citric acid solution in a reagent bottle for later use. 2.7 Copper standard solution
2.7.1 Weigh 0.1000g electrolytic copper, place it in a 250ml beaker, add 10ml nitric acid (1+1), dissolve and cool, add 100ml water, transfer to a 2000ml volumetric flask, dilute to the scale with water, and mix well. This solution contains 0.05mg copper in 1ml. 2.7.2 Take 100.00ml of copper standard solution (2.7.1) and place it in a F200ml volumetric flask, dilute to the mark with water and mix well. This solution contains 0.025mg copper in 1ml.
3 Instrument
Spectrophotometer. www.bzxz.net
4 Sample
The sample should all pass through a 1.68mm sieve.
5 Analysis steps
5.1 Sample quantity
Weigh 0.2500g of sample.
National Bureau of Standards Issued on April 15, 1985
Implemented on January 1, 1986
5.2 Blank test
Carry out a blank test along with the sample.
5.3 Determination
GB 4702.10—85
5.3.1 Place the sample (5.1) in a 300ml beaker, add 20ml sulfuric acid solution (2.1), heat at low temperature until the sample is completely dissolved, cool, transfer to a 50ml volumetric flask, dilute to scale with water, and mix. Transfer 25ml of the solution to a 125ml separatory funnel. 5.3.2 Add 25ml citric acid solution (2.6) and 5ml EDTA solution (2.5), neutralize the solution with ammonium hydroxide (2.2) to about pH 9 (check with precision pH test paper), add 10ml copper reagent solution (2.4), add 20.00ml methyl chloride, shake for 2min, let stand to separate, and discard the aqueous phase.
5.3.3 Transfer the organic phase into a 1 cm cuvette and measure its absorbance at a wavelength of 430 nm using chloroform as a reference on a spectrophotometer.
Subtract the absorbance of the blank test performed with the sample. 5.3.4
5.4 Drawing of working curve
Pipette 0.00, 0.50, 1.00, 2.00, 3.00, 4.00, 5.00 ml of copper standard solution (2.7) into a 125 ml separatory funnel and proceed as in 5.3.2 and 5.3.3. Subtract the absorbance of the reagent blank. Draw the working curve with the copper amount as the abscissa and the absorbance as the ordinate.
6 Calculation of analysis results
Calculate the percentage of copper according to the following formula:
Where: m-
——the amount of copper found from the above curve, g: mg——the amount of sample, g ;
-Test solution split ratio.
Analysis results are accurate to the second decimal place. 7 Allowable error
The difference in analysis results between laboratories should not be greater than the allowable error listed in the following table. Copper
0.010-0.020
0.020~0.050
0.050~0.100
Additional instructions:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Hunan Ferroalloy Factory. -×100
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. 226
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