SH/T 0297-1992 Determination of calcium content in additives

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

1. Method number / full title / English title / replacement relationship

• Standard number: SH/T 0297—92
• Chinese title: Determination of calcium content in additives
• English title: not provided in the available source
• Replacement relationship: replaces SY 2678—82
• First published: 1977 (see the supplementary notes)
• Approval/implementation: approved by China Petrochemical Corporation on 1992-05-20; implemented on 1992-05-20

2. Scope and exclusions

• Scope: this standard applies to calcium-containing additives.
• Interference: the presence of barium and zinc interferes with the determination.
• Exclusions: the available source does not explicitly list excluded materials, apart from the interference statement.

3. Principle

After ignition of the sample at high temperature, dissolve the residue in hydrochloric acid. At a pH greater than 12.5, add a specified amount of magnesium, then calcium indicator, and titrate with EDTA standard volumetric solution.

4. Reagents and materials (purity / preparation)

• 5.1 Hydrochloric acid: analytical reagent grade. Prepare a 19% (m/m) hydrochloric acid solution.
• 5.2 Sodium hydroxide: analytical reagent grade. Prepare a 100 g/L sodium hydroxide solution.
• 5.3 Magnesium chloride: analytical reagent grade. Prepare a 2 g/L magnesium chloride solution.
• 5.4 Sodium chloride: analytical reagent grade.
• 5.5 Disodium ethylenediaminetetraacetate: analytical reagent grade. Prepare EDTA standard volumetric solution with c(EDTA)=0.01 mol/L in accordance with SH/T 0079, and standardize its concentration.
• 5.6 Triethanolamine: analytical reagent grade. Prepare a 40% (V/V) triethanolamine solution.
• 5.7 Calcium indicator: weigh 0.1 g of calcium indicator and 10 g of sodium chloride, mix and grind uniformly, then store in a wide-mouth bottle with a ground-glass stopper (usable for half a year).
• 5.8 Malachite green indicator: prepare a 1 g/L ethanolic indicator solution.
• 4.2 Material: quantitative filter paper, diameter 9 cm.

5. Apparatus

• 4.1.1 Porcelain crucible: 30 mL.
• 4.1.2 Burette: 25 mL.
• 4.1.3 Conical flask: 250 mL.
• 4.1.4 Pipette: 20 mL.
• 4.1.5 Weighing bottle: 10 mL.
• 4.1.6 Watch glass: diameter 9 cm.
• 4.1.7 Volumetric flask: 1000 mL.
• 4.1.8 Graduated cylinder: 10 mL.
• 4.1.9 Beaker: 50 mL.
• 4.1.10 Short glass rod with a rubber sleeve.
• 4.1.11 High-temperature furnace: capable of heating to and maintaining 800±25 ℃. Equipped with a thermocouple and a millivoltmeter with a scale of 1000 ℃ and graduations no greater than 25 ℃.
• 4.1.12 Balance: sensitivity 0.1 mg.

6. Recommended operating conditions

• Ignition temperature: 800±25 ℃.
• Ignition time: 10 min.
• Titration pH: greater than 12.5.
• Other recommended operating conditions are not provided in the available source.

7. Sampling and sample preparation

• 6.1 Into a 30 mL porcelain crucible, weigh a sample corresponding to approximately 5 mg of calcium, to the nearest 0.0002 g (approximately 0.1 g for a typical calcium additive).
• 6.2 Roll half a sheet of quantitative filter paper into a cone with an ignition wick. Place it upright in the porcelain crucible containing the sample so that it covers most of the sample surface.

8. Analytical procedure

• 6.3 Heat the porcelain crucible on an electric heater. When copious oil fumes appear, ignite the wick of the filter-paper cone. After the combustible material has burned off, place the crucible in the high-temperature furnace at 800±25 ℃ for 10 min, then remove it. After cooling, moisten first with a small amount of distilled water, then dissolve the ash with approximately 2 mL of hydrochloric acid solution (5.1). Transfer the solution to a 250 mL conical flask, add 1 drop of malachite green indicator solution (5.8), and neutralize with sodium hydroxide solution (5.2) until the solution changes from blue to green and finally becomes colourless.
• 6.4 Add approximately 0.1 g of calcium indicator (5.7), approximately 5 mL of magnesium chloride solution (5.3) and approximately 0.5 mL of triethanolamine solution (5.6). Then titrate with EDTA standard volumetric solution (5.5) until the solution changes from red to blue.

9. Qualitative and quantitative determination and calculation

Calculate the calcium content X [% (m/m)] of the sample using the following equation: X = C·V×0.040 08×100 / m = C·V×4.008 / m

where:

• C: actual concentration of the EDTA standard volumetric solution (5.5), mol/L;
• V: volume of EDTA standard volumetric solution (5.5) consumed in the titration, mL;
• m: mass of the sample, g;
• 0.040 08: mass of calcium, in grams, equivalent to 1.00 mL of EDTA standard volumetric solution [c(EDTA)=1.000 mol/L].

(Note: the position of the denominator m in the original equation layout is uncertain because of source-text extraction; confirmation against the source is pending (source-text extraction).)

10. Precision

Repeatability: the difference between duplicate determinations by the same operator shall not exceed the following values.

11. Report

Take the arithmetic mean of the duplicate determinations as the test result.

12. Referenced document

• SH/T 0079 Preparation of reagent solutions for petroleum product testing

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick questions and answers