GB/T 387-1990 Determination of sulfur content in dark petroleum products (Tube furnace method)

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Card type: Test method

1. Method number / Full name / English name / Replacement relationship

• Standard number: GB/T 387-90
• Chinese name: Determination of sulfur content in dark petroleum products (Tube furnace method)
• English name: Dark petroleum products - Determination of sulphur content - Tubular oven method
• Replacement relationship: Replaces GB 387-64
• Approval/Implementation: Approved by the State Bureau of Technical Supervision on 1990-12-14, implemented on 1991-10-01
• Reference adoption: Soviet national standard ГОСТ 1437-75 "Determination of sulfur content in dark petroleum products (Rapid method)" (1984 year 2 month edition)

2. Scope of application and non-applicability

• Applicable: Dark petroleum products with sulfur content greater than 0.1% (m/m), such as lubricating oils, heavy petroleum products, crude oil, petroleum coke, paraffin wax, and sulfur-containing additives, etc.
• Not applicable: Lubricating oils containing metal, phosphorus, and chlorine additives, as well as lubricating oils containing such additives. (The extracted additive name is garbled; requires confirmation against the source standard (source-text extraction), suspected to mean "chlorine additive")

3. Method principle

The sample is burned in an air stream, the sulfurous anhydride generated is absorbed with a hydrogen peroxide and sulfuric acid solution, and the sulfuric acid formed is titrated with a standard sodium hydroxide titrant solution.

4. Reagents and materials (purity / preparation)

4.2 Materials

• 4.2.1 Fine sand (or refractory clay or quartz sand): calcined at 900~950℃ to remove sulfur, and ground fine in a mortar. Sieved through a metal filter with a pore size of 0.25mm, selecting the portion with particle size greater than 0.25mm.
• 4.2.2 White oil: sulfur content less than 5ppm, or pharmaceutical petrolatum meeting the specifications of GB 1790.
• 4.2.3 Medical absorbent cotton.

5 Reagents

• 5.1 Sulfuric acid: analytical grade, prepared as a c(1/2 H₂SO₄)=0.02mol/L sulfuric acid solution.
• 5.2 Sodium hydroxide: analytical grade, prepared as a 40% (m/m) sodium hydroxide solution.
• 5.3 30% Hydrogen peroxide: analytical grade.
• 5.4 Potassium permanganate: chemical grade, prepared as a c(1/5 KMnO₄)=0.1mol/L potassium permanganate solution.
• 5.5 Potassium hydrogen phthalate: primary standard reagent. (The original text reads "potassium hydrogen phthalate", requires confirmation against the source standard (source-text extraction))
• 5.6 95% Ethanol: analytical grade. (The original text reads "ethanol", requires confirmation against the source standard (source-text extraction))
• 5.7 Methyl red indicator: prepared as a 0.2% methyl red ethanol solution.
• 5.8 Methylene blue indicator: prepared as a 0.1% methylene blue ethanol solution.
• 5.9 Mixed indicator: prepared by mixing the indicator solutions of item 5.7 and item 5.8 in a volume ratio of 1:1.
• 5.10 Phenolphthalein indicator: prepared as a 1% ethanol solution. (The original text reads "phenolphthalein", requires confirmation against the source standard (source-text extraction))
• 5.11 Distilled water: meets the grade three water specifications in GB/T 6682.

5. Instruments and equipment

• 4.1.1 Tube-type resistance furnace: horizontal type, length not less than 130mm, furnace chamber diameter approximately 22mm. Equipped with a temperature controller, capable of ensuring heating to 900~950℃, and including a nickel-chromium/nickel-silicon (nickel-chromium/nickel-aluminum) thermocouple device.
• 4.1.2 Porcelain boat: meets the requirements for sulfur determination boat-shaped porcelain boats specified in SH/T 0317, used for holding the sample for combustion. New porcelain boats must be burned at 900~950℃ for 30min before use, then removed, cooled to room temperature, and set aside for use.
• 4.1.3 Quartz tube: with quartz bent tube (see Figure 1), a porcelain tube may also be used.
• 4.1.4 Flow meter: used to measure the flow rate of air introduced, measurement range 0~800mL/min.
• 4.1.5 Gas washing bottles: three (see Figure 2, items 1, 2, 3), used for purifying air, each with a capacity of not less than 250mL.
• 4.1.6 Water jet pump or laboratory air compressor, or use a compressed air line equipped in the laboratory.
• 4.1.7 Graduated cylinder: 250mL.
• 4.1.8 Microburette: 10mL, minimum division 0.05mL, equipped with a bottle, a rubber bulb for pressure liquid, and a calcium chloride tube filled with soda lime.
• 4.1.9 Burette: 25mL, division 0.1mL.
• 4.1.10 Pipettes: 5mL (division 0.05mL), 10mL (division 0.1mL).

6. Recommended operating conditions

• Combustion temperature: 900~950℃
• Air flow rate: approximately 500mL/min
• Combustion time: 30–40min; for petroleum products with an aromatic hydrocarbon content of 50% or greater than 50%, the combustion time is 50–60min
• After combustion is complete, place the quartz tube containing the porcelain boat in the hottest part of the tube-type resistance furnace and roast for an additional 15min

7. Sampling and sample preparation

• 7.1 Weigh the sample to be analyzed into the porcelain boat, accurate to 0.0002g. The sample should be evenly distributed on the bottom of the porcelain boat, and the sample amount should be weighed according to Table 1.

Table 1

• If the sulfur content of the sample is greater than 5% (m/m), pre-dilute with white oil (or pharmaceutical petrolatum) so that its sulfur content is not greater than 5% (m/m).
• Note: When analyzing high-sulfur samples [sulfur content greater than 5% (m/m)], it is permitted to weigh less than 0.03g of sample on a microbalance, accurate to 0.00003g.
• When analyzing petroleum coke, sample according to the relevant provisions for petroleum coke sampling in SH/T 0229 and SH/T 0313. Prepare the sample and crush it in a mortar.
• 7.2 The sample in the porcelain boat must be covered with pre-sieved or calcined fine sand (or refractory clay or quartz sand) (petroleum coke samples may not need to be sprinkled with fine sand).

8. Analysis procedure

• 6.1 c(NaOH)=0.02mol/L Preparation, standardization, and calculation of standard sodium hydroxide titrant solution.
  • 6.1.1 Preparation (two methods):
    • a. Weigh 38g sodium hydroxide (accurate to 0.01g), dissolve in 3L distilled water. Mix the resulting solution carefully, store in the dark for one day and night, then decant the clear upper layer for standardization and analysis use.
    • b. Alternatively, before use, dilute a high-concentration standard sodium hydroxide titrant solution with boiled and cooled distilled water, and if necessary, re-standardize before use for analysis.
  • 6.1.2 Standardization: Weigh 0.08g of potassium hydrogen phthalate dried to constant weight at 110–115℃ (accurate to 0.0002g). Dissolve it in 35mL of fresh, thoroughly re-boiled distilled water, add 3–4 drops of phenolphthalein ethanol solution (5.10), and titrate as quickly as possible with the standard sodium hydroxide titrant solution to be standardized (6.1) (during titration, protect the upper end of the burette with a calcium chloride tube filled with soda asbestos or soda lime), until the solution turns pale pink and remains stable for 30s.
  • 6.1.3 Calculation: The actual concentration of the standard sodium hydroxide titrant solution c(NaOH) (mol/L) is calculated according to formula (1): c(NaOH) = 1000·m₁ / (204.2·V₁) = 0.2042·m₁ / V₁ …(1) Where: m₁—mass of potassium hydrogen phthalate, g; V₁—volume of standard sodium hydroxide titrant solution (6.1) consumed during titration, mL; 0.2042— and 1.00mL—mass of potassium hydrogen phthalate in grams equivalent to the standard sodium hydroxide titrant solution [c(NaOH)=1.000mol/L].
• 6.2 Before the test, wash the receiver, gas washing bottles, quartz bent tube, etc. with distilled water and dry them.
• 6.3 Before assembling the air purification device (see Figure 2), inject potassium permanganate solution (5.4) into gas washing bottle 1 to half its capacity; inject 40% sodium hydroxide solution (5.2) into gas washing bottle 2 to half its capacity; place medical absorbent cotton into gas washing bottle 3. Then connect them in sequence with rubber tubing.
• 6.4 Measure 150mL of distilled water with a graduated cylinder, measure 5mL 30% hydrogen peroxide (5.3) and 7mL sulfuric acid solution (5.1) with two pipettes respectively, and inject into receiver 6. Then stopper the receiver with a rubber stopper, which has a quartz bent tube 8 and an outlet tube 7 connected to a water jet pump. Connect the quartz bent tube to the quartz tube 9. Install the quartz tube horizontally in the tube-type resistance furnace, plug the other end of the quartz tube with a stopper, and connect the side branch to the purification system.
• 6.5 Before conducting the test, check the airtightness of the assembled equipment. Checking method: Connect the side branch of the receiver to the water jet pump, pass air through the entire system, then close the stopcock on the side branch of the purification system. At this time, no air bubbles should appear in the receiver and the air purification system. If leakage occurs, the entire system is not airtight; apply soapy water to all connections and eliminate the leakage.
• 6.6 After the entire apparatus has passed inspection, turn on the power switch of the tube-type resistance furnace, adjust the temperature controller, and slowly heat the quartz tube to 900~950℃. To measure and adjust the heating temperature of the tube-type resistance furnace, insert a thermocouple into the tube-type resistance furnace so that the junction of the thermocouple is located in the center of the tube-type resistance furnace, and its two ends are connected to the temperature controller.
  • Note: If the sulfur content of the laboratory air frequently varies, a U-shaped tube filled with activated carbon may be connected before the gas washing bottle.
• 7.2 Place the porcelain boat containing the sample into the quartz tube (at the front part of the tube furnace inlet). Then quickly stopper the quartz tube, connect a water jet pump or air introduction system, and introduce air into the entire system. The air flow rate is measured with a flow meter, and its flow rate is about 500mL/min. The combustion of the sample is carried out at 900–950℃, and the combustion time is 30–40min; for petroleum products with an aromatic hydrocarbon content of 50% or greater than 50%, the combustion time is 50~60min. The tubular resistance furnace must be gradually moved to the position of the porcelain boat (or the quartz tube slowly moved so that the porcelain boat is gradually placed in the heating section of the tubular resistance furnace), and the sample must not ignite. After combustion is completed, place the quartz tube containing the porcelain boat in the hottest part of the middle of the tubular resistance furnace and roast for an additional 15min.
• 7.3 At the end of the test, gradually move the tubular resistance furnace (or quartz tube) back to its original position, turn off the water jet pump, and remove the receiver. Wash the quartz bent tube with 25mL distilled water, and let the washings flow into the receiver. Add 8 drops of mixed indicator solution (5.9) to the solution in the receiver, and titrate with sodium hydroxide standard titration solution (6.1) until the red-purple changes to bright green. If the sulfur content in the sample is greater than 2% (m/m), use a burette with a capacity of 25mL for titration.
• 7.4 Before the test, carry out a blank test under the same conditions.

9. Qualitative and Quantitative and Calculation Formulas

• 8.1 The sulfur content of the sample X₁ [% (m/m)] is calculated according to formula (2): X₁ = 0.016·c·(V - V₀) × 100 / m …(2) Where: c— the actual concentration of sodium hydroxide standard titration solution (6.1), mol/L; V— the volume of sodium hydroxide standard titration solution (6.1) consumed when titrating the products formed after combustion of the sample, mL; V₀—the volume of sodium hydroxide standard titration solution (6.1) consumed when titrating the blank test, mL; 0.016— the mass of sulfur expressed in grams equivalent to 1.00mL sodium hydroxide standard titration solution [c(NaOH)=1.000mol/L]; m— the mass of the sample, g.
• 8.2 The sulfur content of the diluted sample X₁ [% (m/m)] is calculated according to formula (3): X₁ = 0.016·c·(V₃ - V₀) × 100 / m₃ × m₄ / m₅ …(3) Where: c— the actual concentration of sodium hydroxide standard titration solution (6.1), mol/L; V₃—the volume of sodium hydroxide standard titration solution (6.1) consumed when titrating the products formed after combustion of the sample, mL; V₀—the volume of sodium hydroxide standard titration solution (6.1) consumed when titrating the blank test, mL; 0.016— the mass of sulfur expressed in grams equivalent to 1.00mL sodium hydroxide standard titration solution [c(NaOH)=1.000mol/L]; m₃—the total mass of white oil (or pharmaceutical petrolatum) and the tested sample taken during dilution, g; m₄—the mass of the high-sulfur-content tested sample taken during dilution, g; m₅—the mass of the mixture taken during the test, g.

10. Precision

Judge the reliability of the test results according to the following provisions (95% confidence level).

• 9.1 Repeatability: The difference between two results obtained by the same operator in repeated determinations shall not exceed the value specified in Table 2.
• 9.2 Reproducibility: The difference between two test results submitted by different laboratories shall not exceed the value specified in Table 2.

Table 2

Note: In Table 2, “≥2.0–3.0” is originally “≥2.0–3.0”, suspected to be “>2.0~3.0”, requires confirmation against the source standard (source-text extraction). The sulfur content range corresponding to the last row of Table 2 is not provided in the available source, requires confirmation against the source standard (source-text extraction).

11. Report

• 10.1 Take the arithmetic mean of two results from repeated determinations as the sulfur content determination result of the sample.
• 10.2 Round the test result to 0.01% (m/m).

12. Referenced Documents

• GB 1790 Pharmaceutical petrolatum
• GB/T 6682 Specifications and test methods for water used in analytical laboratories
• SH/T 0229 Sampling method for solid and semi-solid petroleum products
• SH/T 0313 Test method for petroleum coke
• SH/T 0317 Technical conditions for acceptance of porcelain utensils used in 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 Reference Q&A