GB/T 4375.5-1984 Chemical analysis of gallium - Nitrous oxide-acetylene flame atomic absorption spectrophotometry for the determination of calcium content

GB/T 4375.5-1984 Chemical analysis of gallium - Determination of calcium content by nitrous oxide-acetylene flame atomic absorption spectrophotometry GB/T4375.5-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of galliumThe N,O - C,H, flame atomic absorptionspectrophotometric method forthe determination of calcium contentThis standard is applicable to the determination of gallium calcium. Determination range: 0.00030～0.0080%. UDC 669.871 : 543
.42 :546.41
GB 4375.5-84
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 decomposed with nitric acid and hydrochloric acid, and the nitric acid is driven out with hydrochloric acid. In 8N hydrochloric acid solution, gallium is extracted and separated with isopropyl ether, and then a certain amount of strontium salt is added as a release agent. In the nitric acid-hydrochloric acid medium, calcium is determined by absorption spectrophotometer at a wavelength of 422.7nm with an oxidizing nitrogen-acetylene flame.
2 Reagents
2.1 Nitric acid: Use high-grade pure nitric acid (specific gravity 1.42) as the raw material, heat it in a quartz distiller to maintain a slight boiling distillation, and take the middle fraction and store it in a quartz bottle for later use.
2.2 Nitric acid (8N): Prepared with nitric acid (2.1). 2.3 Hydrochloric acid: Purified by non-boiling distillation.
2.4 Hydrochloric acid (8N): Prepared with hydrochloric acid (2.3). 2.5 Isoacetal: First, wash the separatory funnel with 10% hydroxylamine hydrochloride solution or 20% ammonium ferrous sulfate solution to remove peroxides, then transfer it to a distillation flask, distill and purify it on a 180℃ water bath, and collect the fraction of 67～69℃. Then saturate it with hydrochloric acid (2.4). 2.6 Washing liquid: Hydrochloric acid (2.4) saturated with isoacetal (2.5). 2.7 Strontium chloride solution: Weigh 4.5g of high-purity strontium chloride (SrCl2·6H20), dissolve it in water and dilute it to 100ml. This solution contains about 1.5mg of strontium in 1ml.
2.8 Nitric acid-hydrochloric acid mixed acid: Nitric acid (2.2) and hydrochloric acid (2.4) are mixed in equal parts. 2.9 Calcium standard stock solution: Weigh 0.2497g of calcium carbonate (99.99%) that has been pre-dried at 105-110C for 2h and cooled to room temperature in a desiccator, place in a 7300ml beaker, add 20ml of water, drop hydrochloric acid (2.3) until it is completely dissolved and 10ml in excess, boil to drive off carbon dioxide. After cooling, transfer to a 1000ml volumetric flask, dilute to scale with water, and mix. This solution contains 100ug calcium in 1ml. 2.10 Calcium standard solution: Transfer 50.00ml of calcium standard stock solution (2.9), place in a 500ml volumetric flask, add 5ml of hydrochloric acid (2.3), dilute to scale with water, and mix. This solution contains 10μg calcium in 1ml. 3 Instruments
Original absorption spectrophotometer, equipped with oxidation. Nitrogen-acetylene burner, calcium hollow cathode lamp. The original absorption spectrophotometer used should meet the following indicators: National Bureau of Standards 1984-04-30 issued
1985-04-01 implementation
GB 4375.5-84
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Minimum sensitivity: 1 The absorbance of the highest concentration standard solution of the arithmetic difference concentration standard solution used in the curve should not be less than 0.400. 1 Curve linearity: In the arithmetic difference concentration standard solution, the difference between the highest and second highest concentration standard solutions should not be less than 0.9 times the difference in absorbance of the lowest concentration standard solution! Minimum stability: 1 The coefficient of variation of the absorbance obtained by multiple measurements of the highest concentration standard solution and the zero concentration solution used in the curve relative to the average absorbance of the highest concentration standard solution should be less than 1.0% and 0.6% respectively. For the calculation of the coefficient of variation in the minimum stability, see Appendix A (Supplementary). For the operating conditions of the GGX-2 type absorption spectrophotometer, see Appendix B (Reference). 4 Analysis steps 4.1 Quantity of determination Weigh 3 samples for determination and take the average value. 4.2 Sample quantity Weigh the samples according to Table 1. 0.01030 ~ 0.0110 0.0010 ~ 0.014 0.0040 ~ 0.0080 4.3 Empty test Carry out a self-test with the sample.
4.4 Determination
Test sample
Nitric acid
Hydrochloric acid
Strontium chloride
Solution volume
Test solution
4.4.1 Place the sample (4.2) in a 50ml English beaker and heat at low temperature for 1. Add nitric acid (2.1) dropwise according to Table 1 while hot and let stand for a while to allow the sample to completely oxidize and disperse into small particles. Add hydrochloric acid (2.3) according to Table 1 and wait for the violent reaction to stop, then heat at low temperature to dissolve. When the sample is no longer reacted, add nitric acid (2.1) in batches (5 drops each time) until it is completely dissolved and evaporate until salts begin to precipitate. Add 1ml hydrochloric acid (2.3) and evaporate again until salts begin to precipitate, remove and cool slightly. 4.4.2 Add 5ml hydrochloric acid (2.4) and dissolve the salts by slight heat, remove and cool to room temperature. 4.4.3 Use 5 ml of hydrochloric acid (2.4) to transfer the solution (4.4.2) into a 50 ml separatory funnel, add 10 ml of isolactone (2.5), shake for 2 min, let stand to separate, transfer the aqueous phase into 13 ml of nitric acid evaporator, place in a dustproof evaporator and bake with infrared lamp until the temperature is close to 1. 4.4.4 Add nitric acid-hydrochloric acid mixed acid (2.8) according to Table 1 to dissolve, transfer into 10 ml or 25 ml colorimetric tube with water according to Table 1, add strontium chloride solution (2.7), dilute to scale with water, and mix. 4.4.5 Measure the absorbance of the solution (4.3 and 4.4.4) at the original absorption spectrophotometer at a wavelength of 422.7 nm using a nitrogen oxide-acetylene fast flame and adjust to zero with water. 4.5.1 Plotting the curve
4.5.1 When the calcium content is 0.00030~0.0040%, take 0, 0.20, 0.40, 0.60, 0.80, 1.00, 1.20ml of calcium standard solution (2.10), -10ml colorimetric solution, add 1.0ml of nitric acid-hydrochloric acid mixture (2.8), 1.00)ml of chloride Strontium solution (2.7), dilute to scale, mix. When the calcium level is greater than 0.0040~0.008), take 0, 0.50, 1.00, 1.50, 2.00, 2.50, 3.00 ml of calcium standard solution (2.10), put it into a 25 ml colorimetric medium, add 2.5 ml of nitric acid-hydrochloric acid mixture (2.8), 2.50 ml of strontium chloride solution 288
GB 4375.5-84
(2.7), dilute to scale with water, mix. 4.5.2 Measure the absorbance of the solution (4.5.1) according to 4.4.5. Draw a curve with calcium concentration as the horizontal axis and absorbance (minus the absorbance of zero concentration) as the vertical axis. Calculation of analysis results
Calculate the percentage of calcium according to the following formula:
Ca(%):
(C2-C.) V
mo×106
× 100
Wherein: C2——Calcium concentration of the sample solution obtained from the I curve, μg, ml; C,——Calcium concentration of the blank solution accompanying the sample obtained from the I curve, μg, ml; V
Volume of the solution to be tested, ml;
mo—Sample volume, g.
6 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0.0003~0.0010
0.0010~6,0040
0.0040~0.0080
GB 4375.5--84
Appendix Awww.bzxz.net
Calculation of the minimum stability coefficient of variation
(Supplement)
The coefficient of variation of the absorbance readings of the highest concentration standard solution and the zero concentration solution is calculated as follows: 100
E(CC)?
(0-0)2
Where: S. —Percent coefficient of variation of the absorbance of the highest concentration standard solution, C———Absorbance of the highest concentration standard solution; C is the average value of the absorbance of the highest concentration standard solution; n--
-Number of measurements;
S. White coefficient of variation of the absorbance of the zero concentration solution, 0 is the absorbance of the zero concentration solution;
-The half mean of the absorbance of the zero concentration solution. 290
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Additional remarks:
GB 4375.5--84
Appendix B
Working condition parameters of GGX-2 atomic absorption spectrophotometer (reference part)
Spectral passband
Lamp current
Burner
This standard is proposed by China Nonferrous Metals Industry Corporation. Recorder
Paper feed speed
mm/min
Lifting amount
ml,min
This standard was drafted by China Nonferrous Metals Industry Corporation Nonferrous Metals Research Institute. The main drafter of this standard is Fan Ying.
Nitrous oxide
kg/cm2
acetylene flow
adjust to red feather fire
flame height is about 15mm
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