SH/T 0231-1992 Determination of hydrogen sulfide content in liquefied petroleum gas (chromatographic method)

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Card type: Test method

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

• Standard number: SH/T 0231-92
• Chinese name: Determination of hydrogen sulfide content in liquefied petroleum gas (chromatographic method)
• English name: not provided in the available source
• Replacement relationship: replaces SY 2082-85
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• Applicable to liquefied petroleum gas.
• Hydrogen sulfide content range: 5～500 mg/m³.
• Not applicable: not provided in the available source.

3. Method principle

Load coarsely porous silica gel impregnated with lead acetate into a glass reaction tube. When the gas sample passes through the silica gel layer, hydrogen sulfide reacts with lead acetate to form black lead sulfide, causing a stained layer of a certain length to appear on the silica gel layer. Determine the amount of hydrogen sulfide that passed through the reaction tube based on the volume of stained silica gel, and then calculate the hydrogen sulfide content in the sample based on the measured sample volume.

4. Reagents and materials (purity / preparation)

• All reagents used are of analytical grade.
• 4.1 Sodium acetate.
• 4.2 Glacial acetic acid.
• 4.3 Xylenol orange: prepare as 5 g/L xylenol orange indicator solution.
• 4.4 Methyl orange: prepare as 5 g/L methyl orange indicator solution.
• 4.5 Eriochrome black T: prepare as 5 g/L Eriochrome black T- ethanol indicator solution.
• 4.6 Ammonia water: prepare by volume ratio as a 1:1 solution and 10% (m/m) ammonia water solution.
• 4.7 Hydrochloric acid: prepare as 19% (m/m) hydrochloric acid solution.
• 4.8 Zinc oxide: primary standard reagent.
• 4.9 Ammonium chloride.
• 4.10 Disodium ethylenediaminetetraacetate (EDTA).
• 4.11 Lead acetate.
• 5.1 Preparation of acetic acid-sodium acetate buffer solution (pH 5.6～6.0): weigh crystalline sodium acetate 200 g, dissolve with distilled water, add glacial acetic acid 10 mL, dilute with distilled water to 1 L, and shake well.
• 5.2 Preparation of ammonia-ammonium chloride buffer solution (pH about 10): weigh 54 g ammonium chloride, to the nearest ±0.01 g, dissolve in 200 mL water, add 350 mL ammonia water, and dilute with water to 1 L. (Note: the original text source-text extraction is “548”, suspected to be “54 g”, requires confirmation against the source standard (source-text extraction))
• 5.3 Preparation and standardization of EDTA standard titration solution [c(EDTA)=0.05 mol/L]: weigh 20 g EDTA, dissolve in 1 L water, and shake well. Weigh primary standard zinc oxide 0.13 g that has been ignited at 800℃ to constant weight, to the nearest 0.0002 g. Moisten with a small amount of water, add 2 mL hydrochloric acid solution [19% (m/m)] to dissolve it, add 10 mL water, neutralize with ammonia water solution [10% (m/m)] until pH is 7～8, then add 10 mL ammonia-ammonium chloride buffer solution (pH≈10). Titrate with the prepared EDTA solution; near the end point, add 3 drops of 5 g/L Eriochrome black T- ethanol indicator solution, and continue titrating until the solution changes from purple to pure blue. Perform a blank test at the same time.
• 5.4 Preparation and standardization of lead acetate standard solution: weigh crystalline lead acetate 20 g, add to a 1 L volumetric flask, then add glacial acetic acid 50 mL and distilled water 500 mL, shake to dissolve the lead acetate, add distilled water to the mark, and shake well. Accurately measure 20 mL of the above solution, place in a 250 mL Erlenmeyer flask, add 1 drops of methyl orange indicator solution, then neutralize this solution with 1:1 ammonia water solution; when the orange color has just turned yellow, add 20 mL acetic acid-sodium acetate buffer solution, 50 mL distilled water, and 1 drops of xylenol orange indicator solution, and titrate with EDTA standard titration solution until the solution changes from wine red to bright yellow as the end point. During standardization, perform a blank test at the same time.
• 5.5 Preparation of impregnated silica gel: soak the silica gel with hydrochloric acid for 2 h, then rinse with water. Then wash with distilled water until neutral, and dry at 120℃. Accurately measure 20 mL lead acetate standard solution and 150 mL distilled water, place in a 500 mL beaker and mix, add the dried silica gel 100 g, stir thoroughly, then impregnate for 2 h, then place in an oven at 65±3℃, stirring once every 30 min, until the water content is 25～35%, then take out, cool, and accurately weigh.
• Materials:
  • 3.2.1 Silicone rubber sheet: 5 mm thick puncture-resistant silicone rubber sheet.
  • 3.2.2 Silica gel: grind coarse-grained coarsely porous silica gel, and sieve out silica gel between 40～80 mesh.

5. Instruments and equipment

• 3.1.1 Glass reaction tube: with a porous glass partition at the lower end. For the 1 mL tube, the minimum graduation of the volume scale is 0.01 mL; for the 2 mL tube, the minimum graduation of the volume scale is 0.02 mL.
• 3.1.2 Sampler: as shown in Figure 1. It can hold about 5 g of liquefied petroleum gas. Each sampler must pass a hydraulic test of 4 MPa (40 kgf/cm²).
• 3.1.3 Stainless steel hollow needle: as shown in Figure 2. Cut a φ1×0.2 mm stainless steel tube into lengths of 70 mm, machine both ends into a conical shape, and drill a φ0.3 mm small hole at a distance of 5 mm from the end. Weld a stainless steel tube with an outer diameter of 2 mm, an inner diameter of 1 mm, and a length of 20 mm in the middle of the needle.
• 3.1.4 Stainless steel needle valve: as shown in Figure 3. Any suitable stainless steel needle valve of various types.
• 3.1.5 Wet test meter: 2 L wet test meter.
• 3.1.6 Support: any type of rack that can secure the needle valve.
• 3.1.7 Glass ampoule: 1, 2 mL.
• 3.1.8 Volumetric flask: 1 L.
• 3.1.9 Pipette: 20 mL.
• 3.1.10 Burette: 50 mL.
• 3.1.11 Graduated cylinder: 50, 100 mL.

6. Recommended operating conditions

• Drying temperature for impregnated silica gel: 65±3℃.
• Drying temperature for silica gel: 120℃.
• Sample vaporization acceleration: a beaker containing 50～80℃ hot water may be used, and the lower one third of the sampler is immersed in the hot water.
• Other operating conditions are not provided in the available source.

7. Sampling and sample preparation

• 6.1 Sampling: on the apparatus where the hydrogen sulfide content needs to be analyzed, install a sampling valve and a sampling port that can secure the silicone rubber plug. The distance from the sampling port to the apparatus should be as short as possible, and stainless steel tubing should be used. Before sampling, first open the sampling valve to discharge the liquefied petroleum gas remaining in the tubing, then close the sampling valve. Install the silicone rubber plug on the sampling port and the sampler, then open the sampling valve and insert one end of the stainless steel needle into the sampling port and the sampler plug in turn, allowing liquefied petroleum gas to flow into the sampler; pull the stainless steel needle out of the sampling port plug, release the air and liquefied petroleum gas in the sampler in gas form, repeat twice, then insert the stainless steel needle into the sampling port plug to take the sample. When the liquefied petroleum gas has filled about four fifths of the sampler, pull the stainless steel needle out of the sampler plug and the sampling port plug in turn, and close the sampling valve. If the sample is loaded too full or the hydrogen sulfide content is too high, the sampler may be inverted, a stainless steel needle inserted, and part of the liquefied petroleum gas released in liquid form.
• Note: when installing the silicone rubber plug on the sampler, a wrench must not be used; only the screw cap on it may be tightened by hand. Samplers containing liquefied petroleum gas must be carried and placed carefully to prevent dropping and collision; the stainless steel screw cap must not be pointed at people, it must not be exposed to sunlight, and it must be placed in a cool place.
• Sample preparation: filling with impregnated silica gel: load the impregnated silica gel into a 2 L reaction tube, tap it tight to the marked line, pour it out and weigh it. On an analytical balance, weigh out the impregnated silica gel required to fill each reaction tube to the marked line, place it into the corresponding ampoule, and seal it for later use.

8. Analytical procedure

• 6.2 Sample introduction: the measurement apparatus is shown in Figure 3. Open the ampoule containing the impregnated silica gel, pour the silica gel into the corresponding reaction tube, and tap it tight to the marked line. Attach the reaction tube to the stainless steel needle valve with the aid of the silicone rubber sealing sheet and the compression nut, and connect the outlet of the reaction tube to the wet test meter with a latex tube. Attach the stainless steel needle to the inlet of the valve. Insert the other end of the stainless steel needle into the sampler plug, and adjust the needle valve to control the sample gas flow rate so that the interface of the stained layer moves upward uniformly. When the interface hardly moves, if there is still sample in the sampler, a beaker containing 50～80℃ hot water may be used, and the lower one third of the sampler is immersed in the hot water, so as to accelerate the vaporization rate of the liquid sample. After all the sample in the sampler has vaporized, pull the stainless steel needle out of the sampler plug, read the volume of the stained silica gel from the reaction tube, and read the volume of the liquefied petroleum gas from the wet test meter.

9. Qualitative and quantitative determination and calculation formula

• EDTA The actual concentration of the standard titration solution c(EDTA), mol/L, is calculated according to formula (1): c(EDTA) = m / [(V₁ - V₀) × 0.08137] … (1) In the formula: m— mass of zinc oxide, g; V₁—amount of EDTA solution used, mL; V₀—amount of EDTA solution used in the blank test, mL; mass of zinc oxide, expressed in grams, equivalent to 0.08137— and 1.00 mL EDTA standard titration solution [c(EDTA)=1.000 mol/L].
• The number of milligrams of lead contained per milliliter of lead acetate standard solution (T₁) is calculated according to formula (2): T₁ = (A - A₀) × C × 207 / 20 … (2) In the formula: A— volume of EDTA standard titration solution consumed in titrating the lead acetate solution, mL; A₀—volume of EDTA standard titration solution consumed in titrating the blank solution, mL; C—EDTA concentration of the standard titration solution, mol/L; mass of lead, expressed in grams, equivalent to 207— and 1.00 mL EDTA standard titration solution [c(EDTA)=1.000 mol/L]. (Note: the original source-text extraction formula is “T, -4-402XCX202”, suspected noise, requires confirmation against the source standard (source-text extraction))
• The number of milligrams of lead contained per gram of impregnated silica gel (T₂) is calculated according to formula (3): T₂ = T₁ × 20 / m₁ … (3) In the formula: m₁—total mass of impregnated silica gel, g.
• The number of milligrams of lead contained per milliliter of impregnated silica gel (T₃) is calculated according to formula (4): T₃ = T₂ × m₂ / 2 … (4) In the formula: m₂—mass of silica gel with volume 2 L, g. (Note: the original formula (4) source-text extraction is incomplete, requires confirmation against the source standard (source-text extraction))
• The number of micrograms of hydrogen sulfide equivalent to each milliliter of silica gel (T_H₂S) is calculated according to formula (5): T_H₂S = T₃ × 34 × 1000 / 207 … (5) In the formula: 34— molecular weight of hydrogen sulfide. (Note: the original formula (5) source-text extraction is “Tws -T:X 90X1000”, suspected noise, requires confirmation against the source standard (source-text extraction))
• The hydrogen sulfide content X (mg/m³) in liquefied petroleum gas is calculated according to formula (6): X = T_H₂S × V₁ / (V₂ - V₀) … (6) In the formula: T_H₂S— micrograms of hydrogen sulfide equivalent to each milliliter of silica gel, μg/mL; V₁—volume of color-changing silica gel, mL; V₀—reading of the wet test meter before sample injection, L; V₂—reading of the wet test meter after sample injection, L.

10. Precision

• Judge the reliability of the test results according to the following provisions (95% confidence level).
• 8.1 Repeatability:
  • 8.1.1 When the hydrogen sulfide content range in the sample is 5～10 mg/m³, the difference between two results obtained by repeated determination by the same operator shall not be greater than 2 mg/m³.
  • 8.1.2 When the hydrogen sulfide content range in the sample is greater than 10 mg/m³, the difference between two results obtained by repeated determination by the same operator shall not be greater than 20% of the smaller result.
• 8.2 Reproducibility: not determined.

11. Report

• 9.1 Take the arithmetic mean of the two repeated determination results as the hydrogen sulfide content of the sample.
• 9.2 Report the indoor temperature and atmospheric pressure at the time of determination.

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 reference