Standards related to:

GB/T 223.53-1987GB 223.53-87

GB

NATIONAL STANDARD

OF THE PEOPLE’S REPUBLIC OF CHINA

UDC 669.14/15.543.06

Methods for chemical analysis of iron, steel and alloy -

The flame atomic absorption spectrophotometric

method for the determination of copper content

APPROVED ON. APRIL 03, 1987

IMPLEMENTED ON. MARCH 01, 1988

Approved by. Ministry of Metallurgical Industry

Table of Contents

1 Method summary ... 3

2 Reagent ... 3

3 Instruments ... 4

4 Analytical procedures ... 5

5 Calculation of analysis results ... 6

6 Precision... 6

Additional information ... 8

Methods for chemical analysis of iron, steel and alloy -

The flame atomic absorption spectrophotometric

method for the determination of copper content

This standard applies to the determination of the amount of copper in cast iron,

carbon steel, and low alloy steel. Measuring range is 0. 005% ~ 0. 50%.

This standard follows the requirements GB 1467-78 “Method for chemical

analysis of metallurgy product - General rules and regulations”.

1 Method summary

The sample is decomposed with hydrochloric acid and nitric acid, perchloric

acid is added to evaporate it to produce smoke, AND water is used to dissolve

the salt. The sample solution is sprayed into the air-acetylene flame, and the

copper hollow cathode lamp is used as the light source. The atomic absorption

spectrophotometer is used to measure the absorbance at the wavelength of

324.7 nm.

To eliminate matrix effects, when drawing the calibration curve, it shall add the

iron the amount of which is similar to that of the sample solution.

2 Reagent

2.1 Hydrochloric acid (ρ 1.19g/ml).

2.2 Nitric acid (ρ1.42 g/ml).

2.3 Perchloric acid (ρ1.67 g/ml).

2.4 Perchloric acid (1 + 1).

2.5 Iron solution. WEIGH 10.00 g of high purity iron (copper content of less

than 0.0005%); PLACE it into an 800 ml beaker; ADD 40 of ml hydrochloric

acid (2.1); ADD about 10 ml of nitric acid (2.2) to dissolve it; after it is

completely dissolved, TRANSFER it into a 500 ml volumetric flask; USE water

to dilute it to the mark; MIX it uniformly. AND 1 ml of this solution contains 20

mg of iron.

2.6 Copper standard solution

2.6.1 WEIGH 1.0000 g of pure copper (more than 99.9%); PLACE it into a 400

ml beaker; ADD 30 ml of (1 + 1) nitric acid to dissolve it; after it is completely

dissolved, TRANSFER it into a 1000 ml volumetric flask; USE water to dilute it

to the mark; MIX it uniformly. AND 1 ml of this solution contains 1.0 mg of

copper.

2.6.2 PIPETTE 10.00 ml of copper standard solution (2.6.1); PLACE it into a

100 ml volumetric flask; USE water to dilute it to the mark; MIX it uniformly.

AND 1 ml of this solution contains 100 μg of copper.

3 Instruments

Atomic absorption spectrophotometer, equipped with air-acetylene burner and

copper hollow cathode lamp. Air and acetylene shall be pure enough

(containing no water, oil, or copper) to provide a stable and clear lean flame.

The atomic absorption spectrophotometer used shall reach the following

indicators.

3.1 The minimum precision requirements. The calibration solution of the

highest concentration is used for absorbance measurements for 10 times,

AND the standard deviation shall not exceed 1.0% of the average absorbance;

the calibration solution of the smallest concentration (not zero calibration

solution) is used for absorbance measurements for 10 times, AND its standard

deviation shall not exceed 0.5% of the average absorbance of the calibration

solution of the highest concentration.

3.2 Characteristic concentration. The characteristic concentration of copper in

a solution having a similar matrix with that of the final measurement sample

shall be less than 0.10 μg of copper/ml.

3.3 Detection limit. The detection limit of copper in a solution having a similar

matrix with that of the final measurement sample shall be less than 0.10 μg of

copper/ml.

3.4 Linearity of calibration curves. The ratio of the slope of the upper 20%

concentration range of the calibration curve (expressed as the change in

absorbance) to the slope of the lower 20% concentration range shall be not

less than 0.70.

4 Analytical procedures

4.1 Sample amount

WEIGH 0.5000 g of sample.

4.2 Blank test

MAKE blank test together with the sample.

4.3 Determination

4.3.1 PLACE the sample (4.1) into a 100 ml beaker; ADD 5 ml of hydrochloric

acid (2.1) and 2 ~ 3 ml of nitric acid (2.2); PLACE it on a hot plate to heat to

dissolve it; ADD 5 ml of perchloric acid (2.3); HEAT it until smoke is generated;

TAKE it off to cool it down; ADD 20 ml of water; HEAT to dissolve the salts;

COOL it down; TRANSFER it into a 100 ml volumetric flask; USE water to

dilute it to the mark; MIX it uniformly. If there is precipitation of carbide, silicate,

and so son, they shall be filtered at dry state.

4.3.2 PLACE the sample solution in the atomic absorption spectrophotometer

at a wavelength of 324.7 nm; USE the air-acetylene flame; USE water to adjust

it to zero; MEASURE its absorbance. Combining with the sample solution

absorbance and the absorbance of the blank solution accompanied with the

sample, FIND the concentration (μg/ml) of copper from the calibration curve.

Note. When the amount of copper is less than or equal to 0.10%, USE the

above solution for direct determination. When the amount of copper is greater

than 0.1%, MAKE determination after appropriately diluting it 5 ~ 10 times.

During dilution, it shall keep the original acidity, AND the blank is diluted same

as that of the sample solution.

4.4 Calibration curve drawing

In six 100 ml volumetric flasks, respectively ADD the iron solution (2.5) of the

similar amount with that of the test solution; then respectively ADD 0.00, 1.00,

2.00, 3.00, 4.00, 5.00 OR 0.00, 2.00, 4.00, 6.00, 8.00, 10.00 ml of copper

standard solution (2.6.2); respectively ADD 10 ml of perchloric acid (2.4); USE

water to dilute it to the mark; MIX it uniformly.

At the atomic absorption spectrophotometer at a wavelength of 324.7 nm, USE

the air-acetylene flame; USE water to adjust zero; MEASURE its absorbance.

The absorbance of each solution of the calibration curve series minus the

absorbance of the zero concentration solution is the net absorbance of the

copper calibration curve series solutions. The copper concentration is used as

the abscissa AND the net absorbance as the ordinate, to draw the calibration

curve.

5 Calculation of analysis results

CALCULATE the percentage of copper by the following formula.

Where.

c2 - Concentration of copper in the sample solution as found from the

calibration curve, μg/ml;

c1 - Concentration of copper in the accompanied sample blank solution as

found from the calibration curve, μg/ml;

f - Dilution factor;

V - Volume of the test sample solution, ml;

m0 - Sample amount, g.

6 Precision

Precision table

degree, % (m/m) Repeatability, r Reproducibility, R

0.005 ~ 0.50 lgr = -1.2751 + 0.9225lgm lgR = -1.0637 + 0.9088lgm

Repeatability is the maximum difference of two independent test results of the

same sample at the 95% probability level under normal and correct operating

conditions using this method by the same operator in the same laboratory

using the same instrument in a short period of time.

Reproducibility is the maximum difference of the two independent test results

of the same sample at 95% probability level under normal and correct

operating conditions using this method by two operators in different

laboratories.

If the difference between two independent test results exceeds the

corresponding value of repeatability and reproducibility, the two results are

considered suspect.

Additional information

This standard shall be under the jurisdiction of the Ministry of Metallurgical

Industry Research Institute of Iron and Steel Technology.

This standard was responsibly drafted by the Iron and Steel Research Institute

of the Ministry of Metallurgical Industry.

This standard was drafted by the Iron and Steel Research Institute.

The main drafters of this standard. Yu Fenglian, Li Jinwen.

This standard’s level marking. GB 223.53-87 I.

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