SH/T 0405-1992 Petroleum jelly heavy metal limit test method

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Card type: Test method

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

• Standard number: SH/T 0405-92
• Chinese name: Petroleum jelly heavy metal limit test method
• English name: not provided in the available source
• Replacement relationship: replaces ZB E42 008-88
• Adoption relationship: equivalent adoption of the Japanese Cosmetic Raw Material Standard (1982) "Petroleum Jelly Heavy Metal Test Method"
• Technical committee: technical coordination by Fushun Research Institute of Petroleum and Petrochemicals
• Drafting organization: drafted by Fushun Research Institute of Petroleum and Petrochemicals
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• Scope of application: This standard applies to the inspection of petroleum jelly, paraffin wax, and white oil for a heavy metal mixture limit, calculated as lead, of 30 ppm(m/m).
• Not applicable: not provided in the available source.

3. Method principle

Under dilute acetic acid acidic conditions, after dilute solutions of heavy metals such as lead, bismuth, copper, cadmium, antimony, tin, and mercury develop color with sodium sulfide, visual colorimetry is used to determine whether the heavy metal content of the sample exceeds the limit.

4. Reagents and materials (purity / preparation)

• 3.1 Sulfuric acid: analytical reagent.
• 3.2 Hydrochloric acid: analytical reagent.
• 3.3 Nitric acid: analytical reagent (the source text source-text extraction is "M acid", requires confirmation against the source standard (source-text extraction)).
• 3.4 Glacial acetic acid: analytical reagent, prepared as 6%(m/m) acetic acid solution; measure 6 mL acetic acid and dilute with water to 100 mL.
• 3.5 Glycerol (glycerin) CH2(OH)CH(OH)CH2(OH): analytical reagent (the molecular formula in the source text source-text extraction contains noise, requires confirmation against the source standard (source-text extraction)).
• 3.6 Lead nitrate: analytical reagent.
• 3.7 Sodium sulfide: analytical reagent.
• 5.1 Preparation of lead standard stock solution: accurately weigh 159.8 mg lead nitrate, first dissolve it in a beaker with a small amount of distilled water and 1 mL nitric acid, then transfer to a 1000 mL volumetric flask, and dilute to the mark with distilled water. The service life of this standard stock solution is two months; it should be re-prepared when turbidity and precipitate appear.
• 5.2 Preparation of lead standard solution: take 10 mL lead standard stock solution, add distilled water and dilute to 100 mL; this solution contains 0.01 mg lead per milliliter, and is prepared immediately before use.
• 5.3 Preparation of sodium sulfide solution: dissolve 5 g sodium sulfide in 10 mL distilled water and add 30 mL glycerol; or dissolve 5 g sodium hydroxide in 30 mL distilled water, and add 90 mL glycerol; after cooling, saturate half of its volume with hydrogen sulfide, then mix with the remaining half. Store in an amber bottle and fill the bottle as much as possible. The service life of this solution is three months, and it should be stored in a cool place. Note: If abnormal color development occurs, the sodium sulfide solution should be re-prepared.

5. Instruments and equipment

• 4.1 Porcelain crucible: 50 mL.
• 4.2 Nessler colorimetric tube: 50 mL.
• 4.3 Graduated cylinder: 10, 20, 50, 10 mL (thus in the source text, suspected to be 100 mL, requires confirmation against the source standard (source-text extraction)).
• 4.4 Pipette (graduated): 5, 100 mL (thus in the source text, requires confirmation against the source standard (source-text extraction)).
• 4.5 Volumetric flask: 10, 1000 mL (thus in the source text, requires confirmation against the source standard (source-text extraction)).
• 4.6 Adjustable-temperature electric furnace.
• 4.7 Constant-temperature water bath.
• 4.8 High-temperature furnace.
• 4.9 Table balance: load capacity 200 g, sensitivity 0.2 g (the source text source-text extraction is "2008, sensitivity 0. 2&", requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Ashing temperature: 500 ℃±25 ℃ (source text note 1: the original ignition temperature was 450–550 ℃, this standard changes it to 500 ℃±25 ℃).
• Ashing time: 2 h (source text note 2: the original ignition time was not specified, this standard specifies the ignition time as 2 h).
• Color development standing time: 5 min (Note: after color development, a standing time of 5 min is most suitable; after about 10 min, due to precipitation of sulfur, the solution begins to show a whitish turbidity, which affects colorimetric judgment, so the test solution and standard colorimetric solution are required to develop color simultaneously).

7. Sampling and sample preparation

• 5.4 Preparation of test portion: weigh 10 g sample into a porcelain crucible, wet the sample with a small amount of sulfuric acid, place on an electric furnace, and slowly heat in a fume hood until carbonized; then, wet the sample again with sulfuric acid and slowly heat to carbonize until almost no white smoke is emitted. Then transfer the crucible to a high-temperature furnace, and at 500 ℃±25 ℃ ignite and ash the residue for 2 h; after cooling, add 2 mL hydrochloric acid and 0.5 mL nitric acid to the crucible and evaporate to dryness on a water bath. Add 2 mL acetic acid solution to the residue, transfer all into a Nessler colorimetric tube, rinse the crucible three times with a small amount of distilled water, pour the rinse liquid into the Nessler colorimetric tube, add distilled water to 50 mL, shake well, and use this as the test solution.
• Note: During carbonization, the heating intensity must be controlled to avoid the sample overflowing or splashing out of the crucible due to volume expansion.

8. Analytical procedure

• 5.5 Preparation of standard colorimetric solution: add to a blank Nessler colorimetric tube the solution obtained by the same treatment as the test solution, then add 3 mL lead standard solution. Then, add 2 mL 1 mol/L acetic acid solution and distilled water to 50 mL, shake well, and use this as the standard colorimetric solution.
• 5.6 Visual colorimetry: add 1 drops of sodium sulfide solution to the test solution and the standard colorimetric solution respectively, shake well, and after standing for 5 min, use white paper (or a white plate) as the background, place the two Nessler colorimetric tubes vertically side by side, remove the stoppers, and visually compare the depth of color development of the solutions from above or from the side.

9. Qualitative and quantitative determination and calculation formula

• 6 Expression of test results: if the color of the test solution is not deeper than the color of the standard colorimetric solution, the heavy metal content is lower than the limit; otherwise, it exceeds the limit.
• If both results of duplicate determinations are not deeper than the color of the standard colorimetric solution, report that the heavy metal content of the sample (calculated as lead) is not greater than 30 ppm(m/m); otherwise, it is greater than 30 ppm(m/m).
• Calculation formula: not provided in the available source.

10. Precision

Not provided in the available source.

11. Report

• If both results of duplicate determinations are not deeper than the color of the standard colorimetric solution, report that the heavy metal content of the sample (calculated as lead) is not greater than 30 ppm(m/m); otherwise, it is greater than 30 ppm(m/m).
• Other report format requirements: not provided in the available source.

12. Referenced documents

Not provided in the available source.

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 Q&A