SH/T 0689-2000 Total sulfur in light hydrocarbons, engine fuels and other oils by ultraviolet fluorescence

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Card type: Test method

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

• Method number: SH/T 0689-2000
• Chinese full name: Standard Test Method for Determination of Total Sulfur in Light Hydrocarbons, Engine Fuels, and Other Oils (Ultraviolet Fluorescence Method)
• English name: Standard test method for determination of total sulfur in light hydrocarbons, motor fuels and oils by ultraviolet fluorescence
• Replacement relationship: not provided in the available source
• Adoption relationship: equivalent adoption of ASTM D5453-1993
• Approval/implementation: approved by the State Bureau of Petroleum and Chemical Industry 2000-06-05, implemented on 2000-12-01
• Responsible organization: Sinopec Research Institute of Petroleum Processing
• Drafting units: Shanghai Refinery of Shanghai Gaoqiao Petrochemical Company, Fushun Research Institute of Petroleum and Petrochemicals
• Main drafters: Wu Guoliang, Wang Lijun

2. Scope of application and non-applicability

• 1.1 is applicable to the determination of total sulfur content in liquid hydrocarbons with a boiling point range of about 25～400 ℃ and a viscosity range at room temperature of about 0.2～10 mm²/s; it is applicable to naphtha, distillate oils, engine fuels, and other petroleum products with total sulfur content in the range of 1.0～8000 mg/kg.
• 1.2 is applicable to the determination of total sulfur content in liquid hydrocarbons with a halogen content lower than 0.35 %(m/m).
• 1.3 uses SI( International System of Units) as the standard unit of measurement.
• 1.4 This standard involves certain hazardous materials, operations, and equipment, but it is not intended to address all safety issues associated with them; users should establish appropriate safety and protective measures and determine applicable management systems before using this standard.
• Non-applicability: no explicit non-applicability clauses are listed in the available source.

3. Method principle

The hydrocarbon sample is injected directly into a pyrolysis tube or a sample boat, and the sample is delivered by the injector to a high-temperature combustion tube. Under oxygen-rich conditions, sulfur is oxidized to sulfur dioxide (SO₂); the gas generated by combustion of the sample, after water removal, is irradiated with ultraviolet light. Sulfur dioxide absorbs the energy of ultraviolet light and is converted to excited-state sulfur dioxide (SO₂*). When the excited-state sulfur dioxide returns to stable-state sulfur dioxide, it emits fluorescence, which is detected by a photomultiplier tube, and the sulfur content of the sample is calculated from the resulting signal value.

• Warning: Exposure to excessive ultraviolet light is harmful to health. Testers must avoid direct ultraviolet light as well as secondary or scattered radiation light harming all parts of the body, especially the eyes.

4. Reagents and materials (purity / preparation)

• 6.1 Reagent purity: The reagents used in the test are all of analytical grade. If reagents of other purities are used, the precision of the determination shall be ensured.
• 6.2 Inert gas: argon or helium, with purity not less than 99.998% and water content not greater than 5 mg/kg.
• 6.3 Oxygen: purity not less than 99.75%, water content not greater than 5 mg/kg. Warning: Oxygen will violently accelerate combustion.
• 6.4 Solvent: toluene, xylene, isooctane, or other solvents similar to the components in the sample to be analyzed. Blank correction for sulfur content shall be performed on the solvent used to prepare standard solutions and dilute samples. When the solvent used has no detectable sulfur relative to the unknown sample, blank correction is not required. Warning: flammable.
• 6.5 Dibenzothiophene: relative molecular mass 184.26, sulfur content 17.399%(m/m)( (see 6.7 Note).
• 6.6 Butyl sulfide: relative molecular mass 146.29, sulfur content 21.92%(m/m)( (see 6.7 Note).
• 6.7 Thionaphthene (benzothiophene): relative molecular mass 134.20, sulfur content 23.90%(m/m)( (see Note). Note: Chemical impurities shall be corrected.
• 6.8 Quartz wool.
• 6.9 Sulfur standard solution (stock solution), 1000 μg/mL: Accurately weigh 0.5748 g dibenzothiophene (or 0.4652 g butyl sulfide, or 0.4184 g thionaphthene) into a 100 mL volumetric flask, then dilute to the mark with the selected solvent. This standard solution may be diluted to the required sulfur concentration. Note: The amount of standard solution prepared shall be based on the number of uses and time; generally, the validity period of the standard solution is three months.

5. Instruments and equipment

• 5.1 Combustion furnace: electrically heated, capable of reaching 1100 ℃, a temperature sufficient to pyrolyze the sample and oxidize the sulfur therein to sulfur dioxide.
• 5.2 Combustion tube: made of quartz, available in two types. The type used for the direct injection system allows the sample to enter the high-temperature oxidation zone directly. The inlet end of the type used for the boat injection system shall allow the sample boat to enter. The combustion tube must have side arms for introducing oxygen and carrier gas, and the oxidation zone shall be large enough (see Figure 1, Figure 2)) to ensure complete combustion of the sample. Figures 1 and 2 show commonly used combustion tube diagrams; if other structures are used, the precision shall meet the requirements.
• 5.3 Flow control: The instrument must be equipped with a flow controller to ensure a stable supply of oxygen and carrier gas.
• 5.4 Drying tube: The instrument must be equipped with equipment to remove water vapor, so as to remove water vapor from the reaction products before they enter the detector. A membrane dryer may be used, which removes water by selective capillary action.
• 5.5 Ultraviolet fluorescence (UV)) detector: a qualitative and quantitative detector capable of measuring the fluorescence emitted when sulfur dioxide is excited by irradiation from an ultraviolet light source.
• 5.6 Microsyringe: The microsyringe shall be capable of accurately injecting a sample amount of 5～20 μL, with a needle length of 50±5 mm.
• 5.7 Injection system: Either of two injection systems may be used.
  • 5.7.1 Direct injection system: It must be capable of introducing a quantitatively injected sample into the inlet carrier gas stream at a controllable and repeatable rate; the function of the inlet carrier gas is to carry the sample into the oxidation zone. The injector shall be capable of injecting the sample from the microsyringe at a rate of about 1 μL/s. See Figure 3.
  • 5.7.2 Boat injection system: The sample boat and combustion tube are both made of quartz. The extended combustion tube is connected to the inlet of the oxidation zone and purged by carrier gas. The combustion tube shall allow the sample boat to return to its original position, and at this position there shall be a cooling jacket so that the sample boat remains cooled while waiting for injection. The speed of the injector must be controllable and repeatable. See Figure 4.
• 5.8 Circulating chiller (optional): Used for the boat injection method; it is an adjustable device capable of delivering a refrigerant at a constant temperature as low as 4 ℃.
• 5.9 Recorder (optional).
• 5.10 Balance (optional): sensitivity ±0.01 mg.
• 5.11 Volumetric flask: 100 mL (the source text source-text extraction is “100.1”, requires confirmation against the source standard (source-text extraction)).
• Figure 1 Direct injection combustion tube; Figure 2 Boat injection combustion tube; Figure 3 Direct injection system; Figure 4 Boat injection system (the source text contains figures; specific dimensions shall be based on the figures in the source text).

6. Recommended operating conditions

• 9.2 According to the injection mode, adjust the instrument according to the conditions listed in Table 1.
• Table 1 Typical operating conditions:
  • Injector injection speed (direct injection): the source text source-text extraction is “[unreadable character]」/, t”, requires confirmation against the source standard (source-text extraction)
  • Boat injector injection speed (boat injection), mm/min: 140～160
  • Furnace temperature, ℃: 1100±25
  • Pyrolysis oxygen flow rate, mL/min: 450～500
  • Inlet oxygen flow rate, mL/min: 10～30
  • Inlet carrier gas flow rate, mL/min: 130～160

7. Sampling and sample preparation

• 8.1 Take samples in accordance with GB/T 4756. Some samples contain volatile components, so the time for opening the sample container shall be as short as possible; after taking the sample, analyze it as soon as possible to avoid sulfur loss and contamination from contact with the sample container. Warning: For samples taken below room temperature, because expansion of the sample at room temperature may damage the container, do not fill such containers completely and leave sufficient space for sample expansion.
• 8.2 If the sample is not to be used immediately, the sample in the container shall be mixed thoroughly before taking a test portion.
• 11.1 The sulfur concentration of the test sample must be within the sulfur concentration range of the standard solutions used for calibration, that is, greater than the low-concentration standard solution and less than the high-concentration standard solution. If necessary, the sample may be diluted by mass or by volume.
  • 11.1.1 Mass dilution: Record the mass of the sample and the total mass of the sample plus solvent.
  • 11.1.2 Volume dilution: Record the mass of the sample and the total volume of the sample plus solvent.

8. Analytical procedure

• 9 Instrument preparation:
  • 9.1 Install the instrument according to the manufacturer's instructions and perform leak testing.
  • 9.2 According to the injection mode, adjust the instrument according to the conditions listed in Table 1.
  • 9.3 According to the manufacturer's requirements, adjust the sensitivity and baseline stability of the instrument, and perform blank correction of the instrument.
• 10 Calibration:
  • 10.1 Select one of the curves recommended in Table 2. Dilute the sulfur standard solution (stock solution) with the selected solvent to prepare a series of calibration standard solutions whose concentration range shall cover the concentration of the test sample and whose sulfur type and matrix shall be similar to those of the test sample.
  • 10.2 Before analysis, rinse the syringe several times with the standard solution. If bubbles are present in the liquid column, rinse the syringe and draw the standard solution again.
  • 10.3 Determine the standard solution injection amount from the curve selected in Table 2, and inject the quantitative standard solution into the combustion tube or sample boat; there are two optional injection methods.
    • Table 2 Sulfur standard solutions:
      • Curve 1: Sulfur μg/mL: 0.50, 2.50, 5.00; injection amount μL: 10～20
      • Curve 2: Sulfur μg/mL: 5.00, 25.00, 50.00; injection amount μL: 5～10
      • Curve 3: Sulfur μg/mL: 100.00, 500.00, 1000.00; injection amount μL: 5
      • Note: Within the selected operating range, the injection amounts of all test samples shall be the same or similar in order to establish consistent combustion conditions.
    • 10.3.1 To determine the injection volume, fill the syringe to the required scale, pull back so that the lowest liquid level falls to the 10% mark, record the liquid volume in the syringe, after injection, pull back the syringe again so that the lowest liquid level falls to the 10% mark, record the liquid volume in the syringe, the difference between the two volume readings is the injected sample volume. Note: Automatic injection or syringe equipment may be used to replace the manual injection step.
    • 10.3.2 Draw the standard solution with a syringe according to the method described in 10.3.1, or the injection volume may be determined by weighing the syringe before and after injection. If this method uses a precision balance with a readability of ±0.01 mg, better accuracy than the volumetric method can be obtained.
  • 10.4 Once the appropriate amount of standard solution in the microsyringe has been determined, the standard solution should be immediately and quantitatively injected into the instrument; two injection techniques are available for selection.
    • 10.4.1 Direct injection technique: Carefully insert the syringe into the inlet of the combustion tube and position it on the injector. Allow a certain time for the residual standard solution in the needle to first volatilize and burn (needle blank); when the baseline is stable again, immediately start the analysis; when the instrument returns to a stable baseline, remove the syringe.
    • 10.4.2 Boat injection technique: Slowly and quantitatively inject the standard solution into the quartz wool in the sample boat, being careful not to leave the last drop of standard solution on the needle; remove the syringe and start the analysis. Before the sample boat enters the furnace and the sample vaporizes, the instrument baseline should remain stable. Before the sample boat is withdrawn from the furnace, the instrument baseline will stabilize again (see Note 1). When the sample boat has fully returned to its original position, it should remain for at least 1 min to cool before the next injection (see Note 2).
      • Note 1: Slowing the boat injection speed or allowing the boat to remain briefly in the furnace is necessary to ensure complete combustion of the sample.
      • Note 2: The degree of cooling required for the sample boat and the start time of the next injection are related to the volatility of the sample being tested. Before the sample boat enters the furnace, a recirculating chiller is needed to minimize sample volatilization.
  • 10.5 Select one of the following two techniques to calibrate the instrument.
    • 10.5.1 Using one of the methods described in 10.2 to 10.4, measure each calibration standard solution and blank solution, and repeat each measurement three times. Before determining the average integrated response value, subtract the average blank from the measured value of each calibration standard solution (see 6.4) response value. Establish a curve with the average response value as the Y axis and the sulfur content of the calibration standard solution (μg) as the X axis. This curve should be linear. The system performance must be checked with a calibration standard solution at least once per day.
    • 10.5.2 If the system has a calibration function, use one of the methods described in 10.2 to 10.4, measure each calibration standard solution and blank solution three times, and use the average of the three results to calibrate the instrument. If blank correction is required but cannot be performed (see 6.4), a curve may be established according to the manufacturer's instructions using the sulfur content (ng) value of each calibration standard solution and its corresponding average response value; this curve should be linear. The system performance must be checked with a calibration standard solution at least once per day.
  • 10.6 If a curve different from Table 2 is used to calibrate the instrument, select a sample injection volume based on the curve used and close to the concentration of the solution being measured. Note: Injecting a standard solution of concentration 100 ng/μL 10 μL is equivalent to establishing a calibration point of 1000 ng or 1.0 μg sulfur.
• 11 Test procedure:
  • 11.1 Obtain the test sample according to the method described in Chapter 8. The sulfur concentration of the test sample must be within the sulfur concentration range of the standard solutions used for calibration, that is, greater than the low-concentration standard solution and less than the high-concentration standard solution. If necessary, the sample may be diluted by mass or volume.
  • 11.2 Determine the response value of the sample solution according to one of the methods described in 10.2 to 10.4.
  • 11.3 Inspect the combustion tube and other components in the flow path to determine whether the sample has completely combusted.
    • 11.3.1 Direct injection system: If carbon deposits or soot are found, reduce the sample injection volume or lower the injection speed, or take both measures simultaneously.
    • 11.3.2 Boat injection system: If carbon deposits or soot are found on the sample boat, extend the residence time of the sample boat in the furnace; if carbon deposits or soot are found at the outlet end of the combustion tube, reduce the boat injection speed or reduce the sample injection volume, or take both measures simultaneously.
    • 11.3.3 Cleaning and recalibration: According to the manufacturer's instructions, clean the components with carbon deposits or soot. After cleaning and adjustment, reinstall the instrument and check for leaks. Before analyzing samples again, recalibrate the instrument.
  • 11.4 Repeat the determination three times for each sample and calculate the average response value.

9. Qualitative and Quantitative and Calculation Formulas

• 12.1 For instruments calibrated using a standard working curve, the sulfur content X(mg/kg) in the sample is calculated according to formula (1) or formula (2):
  • X=(I−Y)/(S·M·K_g) ……(1)
  • X=(I−Y)/(S·V·K_v) ……(2)
  • Where:
    • D— Density of the sample solution, g/mL;
    • I— Average response value of the sample solution;
    • K_g— Mass dilution factor, i.e., sample mass/total mass of sample plus solvent, g/g;
    • K_v— Volume dilution factor, i.e., sample mass/total volume of sample plus solvent, g/mL;
    • M— Mass of the injected sample solution, measured directly or calculated from injection volume and density, V×D, g;
    • S— Slope of the standard curve, response value/(μg);
    • V— Volume of the injected sample solution, measured directly or calculated from injection mass and density, M/D, μL;
    • Y— Average response value of the blank.
• 12.2 For analyzers equipped with a calibration function but without blank correction, the sulfur content X(mg/kg) in the sample is calculated according to formula (3) or formula (4):
  • X=1000G/(M·K_g) ……(3)
  • X=1000G/(V·D) ……(4)
  • Where:
    • D— Density of the sample mg/μL( without dilution injection), or concentration of the sample solution (volume dilution injection), mg/μL;
    • K_g— Mass dilution factor, i.e., sample mass/total mass of sample plus solvent, g/g;
    • M— Mass of the injected sample solution, measured directly or calculated from injection volume and density, V×D, mg;
    • V— Volume of the injected sample solution, measured directly or calculated from injection mass and density, M×D, μL (original text source-text extraction is "Mx D,[unreadable unit]", requires confirmation against the source standard (source-text extraction));
    • G— Mass of sulfur in the sample displayed by the instrument, μg.

10. Precision

• 13.1 Repeatability: The difference between two test results obtained by the same operator, on the same instrument, under the same operating conditions, on the same sample, under correct operation, only one in 20 times exceeds the following value:
  • r=0.1867X^0.63 (original text source-text extraction is "r[unreadable symbol]0.1867[unreadable exponent symbol]63", requires confirmation against the source standard (source-text extraction))
  • Where: X represents the average of two test results.
• 13.2 Reproducibility: The difference between two independent test results obtained in different laboratories, by different operators, on the same sample, under correct operation, only one in 20 times exceeds the following value:
  • R=0.2217X^0.62 (original text source-text extraction is "R =0.2217X0"2", requires confirmation against the source standard (source-text extraction))
  • Where: X represents the average of two test results.
• 13.3 Bias: The bias of this standard is determined by analyzing a hydrocarbon standard reference material with known sulfur content (SRM); the test results obtained are within the repeatability of this standard.
• 13.4 An example of precision estimation is shown in Table 3:
  • Table 3 Repeatability r and Reproducibility R:
    • Sulfur content mg/kg: 1, 5, 10, 50, 100, 1000, 5000 (original text source-text extraction column order is "1 5 1 0 5 0 [garbled trailing values]", requires confirmation against the source standard (source-text extraction))
    • Repeatability r: 0.187, 0.515, 0.796, 2.195, 3.397, 9.364, 14.492, 39.948 (original text source-text extraction numerical values and sulfur content column correspondence requires confirmation against the source standard (source-text extraction))
    • Reproducibility R: 0.222, 0.975, 1.844, 8.106, [unreadable digit]338 (requires confirmation against the source standard (source-text extraction)), 67.425, 127.575, 560.813

11. Report

not provided in the available source.

12. Referenced Documents

• GB/T 4756 Manual sampling of petroleum liquids

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