GB/T 223.25-1994 English PDF (GBT223.25-1994)

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GB/T 223.25-1994: Methods for chemical analysis of iron, steel and alloy. The dimethylglyoxime gravimetric method for the determination of nickel content
GB/T 223.25-1994
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
UDC 669.14/.15:543
H 11
Replacing GB 223.25-1984
Methods for chemical analysis of iron, steel and alloy
The dimethylglyoxime gravimetric method for the
determination of nickel content
ISSUED ON: JANUARY 17, 1994
IMPLEMENTED ON: OCTOBER 01, 1994
Issued by: The State Bureau of Quality and Technical Supervision
Table of Contents
1 Subject content and application scope ... 3 
2 Method summary ... 3 
3 Reagents ... 3 
4 Analytical procedures ... 4 
5 Calculation of analysis results ... 5 
6 Precision ... 6 
Appendix A Raw data of precision tests ... 7 
Methods for chemical analysis of iron, steel and alloy
The dimethylglyoxime gravimetric method for the
determination of nickel content
1 Subject content and application scope
This Standard specifies the dimethylglyoxime gravimetric method for the
determination of nickel content.
This Standard applies to the determination of nickel in carbon steel, alloy steel,
precision alloys, and high temperature alloys. Determination range: More than
2%.
2 Method summary
In ammonium acetate buffer solution, use sodium sulfite to reduce iron to
divalent; use tartaric acid as complexing agent. At pH 6.0~6.4, nickel and
dimethylglyoxime will precipitate and separate from elements such as iron,
cobalt, copper, manganese, chromium, molybdenum, tungsten, vanadium. The
nickel dimethylglyoxime is dried at 145±5°C and weighed to a constant weight.
3 Reagents
3.1 Hydrochloric acid (ρ1.19 g/mL).
3.2 Hydrochloric acid (1+1).
3.3 Nitric acid (ρ1.42 g/mL).
3.4 Perchloric acid (ρ1.67 g/mL).
3.5 Aqua ammonia (ρ0.90 g/mL).
3.6 Aqua ammonia (1+1).
3.7 Tartaric acid solution (50%).
3.8 Anhydrous sodium sulfite solution (20%): Prepare when used, and use after
filtration.
4.2.3 USE slow-speed filter paper to filter; PLACE the filtrate in a 600 mL beaker;
USE hot water to wash the beaker; WASH the filter paper and precipitate 7~8
times. The total volume of the solution is controlled to about 250 mL.
4.2.4 Under constant stirring, use hydrochloric acid (3.2) to acidify the solution
to about pH 3.5; ADD 20 mL of anhydrous sodium sulfite solution (3.8) and stir
for a while; USE aqua ammonia (3.6) to adjust the solution to pH 4.5. When
heated to 45~50°C, add sodium thiosulfate solution (3.9) (when the copper
content is less than 30 mg, add 10 mL; when it exceeds 30 mg, add 20 mL);
STIR for a while and place 5 min.
4.2.5 ADD dimethylglyoxime ethanol solution (3.11) (calculated according to
adding 0.6 mL per 1 mg of nickel, cobalt and copper, and with an excess of 10
mL). Under constant stirring, add 20 mL of ammonium acetate solution (3.10).
At this time, the pH of the solution shall be 6.0~6.4. If it is lower than this range,
it can be adjusted with aqua ammonia (3.6).
4.2.6 Adjust the total volume of the solution to about 400 mL (the samples
containing cobalt or copper can be controlled at about 500 mL); LET it stand
and age for 30 min (the samples containing cobalt and copper are aged for 1
h).
4.2.7 COOL down to room temperature; USE a constant weight of No. 4 glass
crucible for vacuum filtration (the speed should not be too fast; the precipitate
must not be sucked dry). USE cold water to wash the beaker and the precipitate
(to prevent the precipitate from being sucked dry. It is better to wash with a
small amount of water in many times and make the precipitate disperse. The
total amount of washing water is generally controlled at about 200 mL).
4.2.8 PUT the glass crucible in an oven; DRY it at 145±5°C for about 2 h; COOL
it in a desiccator; WEIGH it, and dry it repeatedly to a constant weight.
5 Calculation of analysis results
Calculate the percentage content of nickel according to the following formula:
Where:
m1 - Mass of glass crucible and dimethylglyoxime nickel precipitation, g
m2 - Mass of glass crucible, g;