GB/T 34101-2017 Determination of hydrogen sulfide content in fuel oils — Rapid liquid-phase extraction method

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Card type: Test method

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

• Standard number: GB/T 34101-2017
• Chinese full title: Determination of hydrogen sulfide content in fuel oils — Rapid liquid-phase extraction method
• English title: Determination of hydrogen sulfide in fuel oils—Rapid liquid phase extraction method
• Method number: This standard includes two test procedures, Method A and Method B (see Chapter 1, Chapter 3, 11.1)
• Replacement relationship: not provided in the available source (the foreword only states that it was drafted in accordance with GB/T 1.1-2009, and does not mention replacing any standard)
• Publication/implementation: published on 2017-07-31, implemented on 2018-02-01
• Custodian: National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280)

2. Scope of application and non-applicability

• Applicable to the determination of hydrogen sulfide content in the liquid phase of fuel oils by the rapid liquid-phase extraction method.
• Applicable to fuel oils with a kinematic viscosity at 50℃ not greater than 3000 mm²/s, including the determination of liquid-phase hydrogen sulfide in marine residual fuels, distillate fuels and petroleum blending component oils.
• Note 1: Also applicable to samples with a kinematic viscosity at 50℃ higher than 3000 mm²/s (see 7.2), but the precision will be affected.
• Note 2: For samples containing thiol or alkyl sulfide interferences at a content higher than 5 mg/kg, if Method B is used for the determination, a higher hydrogen sulfide content will be obtained; Method A may be used to eliminate this effect.
• Note 3: If the sample contains fatty acid methyl esters, there is no effect on the hydrogen sulfide content determination result.
• Not applicable: no explicitly listed non-applicable scope is provided in the available source.

3. Method principle

Inject a test portion of known mass into a heated test tube containing diluted base oil. Bubble air through the test portion oil liquid to extract the hydrogen sulfide gas therein. The purged hydrogen sulfide, together with the air, passes through a filter box cooled to −20℃ (Method A only) and then enters the detector, where the hydrogen sulfide content in the air is measured, thereby calculating the hydrogen sulfide content in the liquid phase of the test portion. Method B omits the relevant steps concerning the low-temperature filter box. (Chapter 3)

4. Reagents and materials (purity / preparation)

• 5.1 Dilution oil: a dedicated colorless API II type base oil, with a kinematic viscosity at 40℃ ranging from 90 mm²/s to 110 mm²/s. The dilution oil shall be ensured to contain no hydrogen sulfide under the test conditions. Note: Use of other diluents such as xylene or toluene will damage the detector.
• 5.2 Verification substance: verification gas or verification liquid.
  • Verification gas: compressed nitrogen as the balance gas, with a purity reaching a volume fraction of 99.999%, a verification gas containing hydrogen sulfide, whose nominal value is traceable to a national standard.
  • Verification liquid: contains a known concentration of liquid-phase hydrogen sulfide. The recommended hydrogen sulfide concentration is 2 mg/kg. Verification liquids will deteriorate over time. Commercially stable verification liquids shall be used within the shelf life specified by the supplier. Unstable verification liquids require special storage conditions to slow down the deterioration time (for example, nitrogen blanketing or storage in a refrigerator), and shall be used within a few hours after calibration. For unstable verification liquids, the user needs to establish storage and use regulations.
  • Note: The verification liquid may be a) a commercially stable verification solution with an independent liquid-phase hydrogen sulfide concentration assignment, or b) a liquid-phase hydrogen sulfide solution whose concentration is prepared and calibrated by a titration method before use.
• 5.3 Toluene: analytical reagent.
• 5.4 Petroleum ether: 60℃~90℃, analytical reagent.
• 5.5 Acetone: analytical reagent.
• 5.6 Filter box: see Figure A.4, individually packaged, used only for Method A.

5. Apparatus and equipment

• 4.1 For the hydrogen sulfide determination apparatus, see Annex A. The apparatus for Method A includes a gas-phase processor; Method B does not include a gas-phase processor.
• 4.2 Analytical balance: single-pan or double-pan, with a readability of 0.001 g.
• 4.3 Syringe or burette: 20 mL, used for injecting dilution oil (5.1), with an accuracy of ±1%.
• 4.4 Pipette: capacity 1 mL, used for adding the test portion. The accuracy shall, as stated by the instrument manufacturer, achieve an error not exceeding ±0.25% at 1000 mL, with a coefficient of variation of 0.04%. For systematic optimization of operation, it is recommended to use a pipette of the model specified by the manufacturer.
• 4.5 Disposable syringe: capacity 5 mL or 10 mL, used for injecting the test portion, with an accuracy of ±1%. A needle may be attached or a rubber tube may be added, to withdraw the test portion from a depth of 3 cm below the sample surface, and at the same time it shall be possible to avoid the test portion adhering to the tube wall when injected into the test tube.
• 4.6 Refrigerator (optional): used for storing samples (see 6.4). The refrigerator should be an explosion-proof refrigerator suitable for storing volatile substances.
• 4.7 Electric furnace/water bath (optional): can heat the sample to 40℃, with a temperature control accuracy of ±2℃ (see 7.2). The electric furnace should be suitable for heating volatile substances.
• 4.8 Ultrasonic cleaner (optional): used for cleaning test tubes (see 11.2.3 and the note after 11.3.3).
• Annex A Apparatus components (A.2):
  • A.2.1 Air pump filter: 5 μm nylon encapsulation, to remove dust from the air.
  • A.2.2 Air pump: capable of providing air at a flow rate of 375 mL/min±55 mL/min.
  • A.2.3 Air inlet filter: carbon type, used for removing moisture and contaminants from the inlet air.
  • A.2.4 Solenoid valve: can cut off the inlet air from the test tube according to the requirements of the normal test procedure; if the hydrogen sulfide concentration is too high, which would cause saturation of the detector, the hydrogen sulfide gas can be cut off from the detector.
  • A.2.5 Flow sensor: an integrated electronic sensor can ensure that the air/hydrogen sulfide mixed gas enters the detector, so that the air flow is controlled, and can detect any flow problems that occur.
  • A.2.6 Liquid trap: 25 mL borosilicate glass tube with an internal inlet tube, used for trapping any liquid and heavy vapor. The top of the glass tube should be filled with loose quartz wool.
  • A.2.7 Moisture filter: 5 μm nylon encapsulation, to remove moisture from the air/hydrogen sulfide mixed gas.
  • A.2.8 Heater: 50 W aluminum heating block, controlling the temperature at 60.0℃±1.0℃, with an overheat protection function.
  • A.2.9 Temperature sensor: platinum resistance thermometer, used for measuring and controlling the heater temperature.
  • A.2.10 Test tube: 50 mL borosilicate glass tube, with an internal inlet tube for conveying air. See Figure A.3. The test tube is heated by the heater.
  • A.2.11 Hydrogen sulfide detector: electrochemical type, dedicated to hydrogen sulfide detection; (gas) measurement range 0 μmol/mol~50 μmol/mol, repeatability 1%, response time T90 less than 30 s.
  • A.2.12 Gas-phase processor (VPP) (Method A only): an electric heating device used for cooling the filter box (5.6) to −20℃, allowing the gas generated in the test tube to pass through the filter box into the hydrogen sulfide detector.

6. Recommended operating conditions

• Air flow rate: 375 mL/min±55 mL/min (9.1, A.2.2).
• Test tube heater temperature: 60.0℃±1.0℃ (9.2, 11.2.2, 11.3.2, A.2.8).
• Gas-phase processor (condenser) temperature: −20.0℃±2.0℃ (Method A only, 9.4).
• The gas-phase processor cooling process is expected to require 10 min (11.2.5).
• Detector reading recording: throughout the entire 15 min test process, the millivolt reading (mV) is recorded at least once every 4 s (11.4.11).
• Instrument use location: should be used in a suitable fume hood, or the exhaust pipe should be connected to an exhaust fan (8.2).

7. Sampling and test portion preparation

• 6.1 Unless otherwise specially specified, sampling shall be carried out in accordance with GB/T 4756. The sampling process shall ensure the integrity of the sample and shall minimize possible hydrogen sulfide loss. When the sampling process cannot ensure minimum hydrogen sulfide vapor loss (for example, continuous drip sampling), a separate dedicated sample shall be taken for the hydrogen sulfide determination.
• 6.2 Place the collected sample directly into a clean hydrogen sulfide inert container, with a container capacity of at least 500 mL. The container closure should facilitate withdrawal of the test portion by pipette (4.4) or syringe (4.5). To ensure the integrity of the sample, the collected sample should fill about 95% of the space of the sample container, and the container cap should be immediately put on and tightened after sampling.
  • Note 1: It is recommended to use a dark brown borosilicate glass bottle or an epoxy resin-lined container, with an impermeable airtight cap.
  • Note 2: A sampling container of slightly smaller capacity may also be used, but the determination precision will be affected.
  • Note 3: Sampling equipment for sampling from the top of a storage tank, and closed-system samplers commonly used for ship compartments surrounded by inert gas, may not allow the sample to be directly taken out and placed into the sample container; in such cases, the sample may be transferred through the sampler into the sample container. However, during the transfer process, hydrogen sulfide loss shall be minimized.
• 6.3 If an epoxy resin-lined container is used, a visual inspection is required to ensure that the lining is not damaged and that the container has no dents.
• 6.4 After sampling, the sample should be sent to the laboratory as quickly as possible for determination. If the sample cannot be determined immediately, it should be stored in a refrigerator (4.6). The sample should be determined within three days after sampling.
• 6.5 The hydrogen sulfide determination should be the first test item for the sample, because any sample handling process will cause hydrogen sulfide loss, resulting in a low determination result.
• 7.1 To reduce hydrogen sulfide loss, do not homogenize the sample, avoid unnecessary agitation of the sample, do not transfer the sample from one container to another, and avoid unnecessary opening of the bottle cap before taking the test portion.
• 7.2 The sample needs to have a certain fluidity to facilitate drawing the test portion with a pipette (4.4) or syringe (4.5). If the sample is difficult to flow at room temperature, it may be gently heated with a water bath or electric furnace (4.7), and the set heating temperature shall not exceed 40℃. Note: Samples with a kinematic viscosity exceeding 500 mm²/s at 50℃ usually require heating.

8. Analysis Procedure

• 8.1 Overview: Set up, verify, calibrate, and operate the instrument correctly according to the manufacturer's instructions.
• 8.2 Instrument location: Because a small amount of hydrogen sulfide may be released, the instrument should be used in a suitable fume hood, or the exhaust pipe should be connected to an exhaust fan.
• 8.3 Filters and connecting tubes:
  • 8.3.1 The air inlet filter needs to be replaced every three months or when discoloration is visually observed.
  • 8.3.2 Determine the replacement interval for the air pump filter and moisture filter according to the manufacturer's instructions.
  • 8.3.3 If discoloration is visually observed, the moisture filter should be replaced.
  • 8.3.4 If discoloration is visually observed, the connecting rubber tube of the test tube should be replaced.
• 9 Verification:
  • 9.1 Air flow rate: At least once a month, connect a calibrated flow meter to the air outlet tube, and verify that the air flow rate is within the range of 375 mL/min±55 mL/min. If the flow rate is inaccurate, recalibrate the flow (10.1).
  • 9.2 Test tube heater: At least once every six months, insert a calibrated platinum resistance thermocouple and verify that the heater temperature is 60.0℃±1.0℃. If the temperature is incorrect, recalibrate the heater temperature (10.2).
  • 9.3 Effectiveness of the hydrogen sulfide detector: At least once a month or when replacing with a new detector, verify the detector performance according to the instrument manufacturer's instructions. Use air (hydrogen sulfide 0 μmol/mol) and nitrogen verification gas containing about 25 μmol/mol hydrogen sulfide (5.2) for verification. If the detection result deviates from the nominal value 10%, replace the moisture filter and check the cleanliness of the liquid trap, test tube, and connecting lines. After purging with air for 30 min, perform the verification again. If the detection result still exceeds the allowable range, the detector needs to be recalibrated or replaced. Verification work should be carried out at room temperature.
  • 9.4 Effectiveness of the gas phase processor (applicable only to Method A): Verify the temperature of the gas phase processor at least once every six months. Insert a calibrated platinum resistance thermocouple and verify that the condenser temperature should be −20.0℃±2.0℃. If the temperature is incorrect, recalibrate the temperature of the gas phase processor (10.4).
  • 9.5 Overall instrument condition verification:
    • 9.5.1 The laboratory may use a verification fluid (5.2) to verify the overall condition of the instrument. It is recommended to perform verification at least once every three months; when a new detector is installed, or according to the laboratory's quality control requirements, measure the hydrogen sulfide verification fluid. It is recommended to perform overall instrument condition verification by participating in interlaboratory proficiency testing programs (PTS).
      • If a commercial verification fluid is used for verification, and the measurement result exceeds the range of the certified reference value of the verification fluid ARV±R/√2 (where R is the method reproducibility), check whether the verification fluid is within its validity period, and re-verify using a verification fluid within the validity period; if it still does not meet the requirement, check according to 9.5.2.
      • If a verification fluid obtained from an interlaboratory proficiency testing program (PTS) is used, and the measurement result exceeds the range of the statistical value or certified reference value ARV of ±R/√2, check according to 9.5.2.
      • Note: This calculation assumes that the uncertainty of the certified reference value ARV of the commercial verification fluid used or the statistical value of the verification fluid obtained from PTS is negligible compared to R/√2. Users are advised to verify this assumption.
      • If an unstable verification fluid is used, and the measurement result exceeds the range of the nominal value ±R/√2, the verification fluid needs to be re-prepared and the verification test re-performed.
    • 9.5.2 If the requirements in 9.5.1 cannot be met, check the air flow rate (9.1) and verify the effectiveness of the hydrogen sulfide detector (9.3); if the requirements still cannot be met, troubleshoot according to the instrument instructions or recalibrate the instrument.
• 10 Calibration:
  • 10.1 Air flow rate: Calibrate the air flow rate according to the instrument manufacturer's instructions.
  • 10.2 Test tube heater: Calibrate the test tube heater temperature according to the instrument manufacturer's instructions.
  • 10.3 Hydrogen sulfide detector calibration: The detector's response to static and dynamic hydrogen sulfide has been calibrated by the instrument manufacturer. Calibration information is stored digitally in the detector assembly and can be read directly by the computer in the instrument. After calibration, measurement results are calculated in units of mg/kg. Install a new detector according to the manufacturer's instructions, and immediately verify its effectiveness (9.3).
  • 10.4 Gas phase processor temperature calibration (applicable only to Method A): Calibrate the gas phase processor temperature according to the instrument manufacturer's instructions.
• 11 Test procedure:
  • 11.1 Overview—Method A and Method B: Method A is recommended for determining the liquid-phase hydrogen sulfide concentration in distillate fuel oils and residual fuel oils. Results determined by Method B will be high due to the presence of mercaptans (mercaptides) or alkyl sulfides in the sample.
  • 11.2 Method A— is applicable to instruments with a filter cartridge and gas phase processor:
    • 11.2.1 Check the moisture filter and liquid trap. If liquid is visually observed or discoloration occurs, replace the filter, empty and clean the liquid trap.
    • 11.2.2 Turn on the instrument and confirm that the heater temperature is 60.0℃±1.0℃. Pump air directly into the detector to purge the instrument.
    • 11.2.3 Clean the test tube and cap before each test. The test tube should be clean and dry before use. Tighten the cap. Note: Cleaning sequentially with toluene (5.3), petroleum ether (5.4), and acetone (5.5) using an ultrasonic cleaner (4.8) is an effective method for cleaning the test tube, cap, and liquid trap.
    • 11.2.4 Insert a new filter cartridge (5.6) into the gas phase processor and tighten the cap.
    • 11.2.5 Start the cooling process of the gas phase processor; it is expected to take 10 min. Before drawing the test portion, ensure that the gas phase processor has completed the cooling cycle and stabilized at the required test temperature. Note: Before the filter cartridge is fully cooled and ready for testing, the detector and gas phase processor are in a locked state, which prevents the sample mass from being input.
    • 11.2.6 Proceed according to the steps in 11.4.
  • 11.3 Method B— is applicable to instruments without a filter cartridge and gas phase processor:
    • 11.3.1 Check the moisture filter and liquid trap. If liquid is visually observed or discoloration occurs, replace the filter, empty and clean the liquid trap.
    • 11.3.2 Turn on the instrument and confirm that the heater temperature is 60.0℃±1.0℃. Pump air directly into the detector to purge the instrument.
    • 11.3.3 Clean the test tube and cap before each test. The test tube should be clean and dry before use. Tighten the cap. Note: Cleaning sequentially with toluene (5.3), petroleum ether (5.4), and acetone (5.5) using an ultrasonic cleaner (4.8) is an effective method for cleaning the test tube, cap, and liquid trap.
    • 11.3.4 Proceed according to the steps in 11.4.
  • 11.4 Method A and Method B:

    • 11.4.1 Unscrew the test tube cap, inject 20 mL±0.5 mL of dilution oil (5.1) with a syringe or burette (4.3), and tighten the cap. Place the test tube into the temperature-controlled heater and connect the input and output lines.

    • 11.4.2 Pump air through the dilution oil in the test tube into the detector for 5 min, so as to warm the dilution oil and purge the system.

    • 11.4.3 Next, pump air directly into the detector without passing through the test tube, so that the hydrogen sulfide concentration in the test portion injected into the test tube will not be affected by the purge air. Before injecting the test portion, ensure that the instrument is operating in bypass mode. Injecting the test portion before this condition is met will cause premature loss of hydrogen sulfide and yield erroneously low results. If this situation is suspected, discard and retest. If an attempt is made to inject the test portion before bypass mode is activated, the instrument will issue a warning.

    • 11.4.4 Table 1 gives the test portion amount required for the test. The test portion should be drawn from below the sample surface by 3 cm, using a disposable syringe (4.5) or a 1 mL pipette (4.4), and avoid touching the bottom of the sample container. Do not draw the test portion under high vacuum, and ensure that the sample container is sealed immediately after the test portion is drawn, so as to minimize possible hydrogen sulfide loss. Do not push air into the test portion with the syringe or pipette. Weigh the test portion with an analytical balance (4.2) to the nearest 0.001 g. Input the total mass including the syringe or pipette and the test portion into the instrument.

    • 11.4.5 Note: If the balance can tare, the net injected amount of the test portion can be input directly instead of inputting the masses before and after injection. If the measured hydrogen sulfide concentration does not match the test portion amount and predicted concentration shown in Table 1, repeat the test with the correct test portion amount. Note: If an incorrect test portion amount is selected, the test precision will be affected.

    • Table 1 Sampling amount determined according to predicted hydrogen sulfide concentration:

      Predicted hydrogen sulfide concentration/(mg/kg)	Sampling amount/mL	Sampling method
      0~10	5	Disposable syringe
      >10~20	2	Disposable syringe
      >20	1	Pipette

    • 11.4.6 Inject the test portion into the test tube, ensuring that the syringe or pipette is vertical to avoid the test portion adhering to the tube wall. Ensure that the syringe or pipette does not touch the surface of the dilution oil. Any dilution oil adhering to or inside the syringe or pipette will increase the mass of the empty syringe or pipette (11.4.8), thereby causing erroneously high results. If this occurs, discard and retest.

    • 11.4.7 Once the test portion is injected into the test tube, immediately tighten the top cap of the test tube.

    • 11.4.8 Weigh the empty syringe or pipette with an analytical balance (4.2) to the nearest 0.001 g, and input the mass into the instrument.

    • 11.4.9 Start the test. The following process will proceed automatically. Once the test portion is injected into the test tube, start the test immediately without delay to avoid possible sample degradation.

    • 11.4.10 The detector reading returns to zero. For method A, air is first pumped directly through filter box 3 min. After 3 min, the air is switched to the test tube and passed through the sample and dilution oil in the test tube. The released hydrogen sulfide is carried by the air stream through the filter box in the gas phase processor into the detector. For method B, air is pumped directly into the test tube containing the sample and dilution oil, and the released hydrogen sulfide is carried by the air stream into the detector.

    • 11.4.11 Throughout the entire 15 min test, the millivolt reading output by the detector (mV) is recorded at least once every 4 s; a typical graphical output for method A is shown in Figure A.5. The result is calculated automatically and displayed as mg/kg.

    • 11.4.12 Pump in air to purge the detector.

    • 11.4.13 Remove and clean the test tube (11.2.3 and 11.3.3). When removing the test tube for cleaning, check that the sample and dilution oil are completely mixed. If obvious two-phase coexistence occurs, check the gas line connections and repeat the test.

    • 11.4.14 For method A, remove the filter box.

9. Qualitative and Quantitative Determination and Calculation Formulas

Calculate the hydrogen sulfide content of the sample in the liquid phase X according to formula (1), expressed in milligrams per kilogram (mg/kg):

X = A·M / m …… (1)

Where:

• A— integral area of the cell output over the entire test duration, in millivolt-seconds (mV·s);
• M— calibration constant of the detector, in micrograms per millivolt-second (μg/mV·s);
• m— mass of the sample, in grams (g).

Expression of results (Chapter 13):

• If the hydrogen sulfide content of the sample is less than 10 mg/kg, the result is rounded to 0.01 mg/kg;
• If the hydrogen sulfide content of the sample is greater than or equal to 10 mg/kg, the result is rounded to 0.1 mg/kg;
• Record the test procedure (method A or method B).

10. Precision

• 14.1 Overview:

  • Method A: The precision data for distillate fuel oils and residual fuel oils are given in 14.2 and 14.3. At the same location, 8 operators using 8 instruments repeatedly determined 12 samples in random order; the hydrogen sulfide content of the samples ranged from 0.60 mg/kg to 12.5 mg/kg. Note: The data come from research conducted in 2012 at the laboratory of the British Energy Institute.
  • Method B (residual fuel oil): The precision data are given in 14.2 and 14.3. At the same location, 7 operators using 7 instruments repeatedly determined 15 samples in random order; the hydrogen sulfide content of the samples ranged from 0.40 mg/kg to 15.3 mg/kg. Note: The data come from research conducted in 2009 at the laboratory of the British Energy Institute.
  • Method B (distillate fuel oil): The precision data are given in 14.2 and 14.3. At the same location, 10 operators using 10 instruments repeatedly determined 8 samples in random order; the hydrogen sulfide content of the samples was 0.40 mg/kg to 9.70 mg/kg. Note: The data come from research conducted in 2011 at the laboratory of the British Energy Institute.
  • Because the data used to determine precision come from test results at the same location, when comparing test data obtained at different times and locations, the reproducibility data may not be comparable due to the influence of sampling, transportation, storage, and environmental factors. In practice, two results obtained from different locations are acceptable when the difference between them does not exceed the published reproducibility.

• 14.2 Repeatability: For the same operator using the same instrument, the difference between two results obtained from repeated determination of the same sample shall not exceed the value given in Table 2. Typical repeatability values for method A and method B are given in Table 3.

• 14.3 Reproducibility: For different operators in different laboratories, the difference between two single and independent results obtained from determination of the same sample shall not exceed the value given in Table 2. Typical reproducibility values for method A and method B are given in Table 4.

• Table 2 Precision:

  Test procedure	Repeatability/(mg/kg)	Reproducibility/(mg/kg)
  Method A (distillate and residual fuel oils)	0.332 9 X^0.55	0.445 9 X^0.58
  Method B (distillate fuel oil)	0.209 9 X^0.61	0.238 9 X^0.38
  Method B (residual fuel oil)	0.297 0 X^0.59	0.523 2 X^0.55

  Note 1: X is the average of two determination results, in milligrams per kilogram (mg/kg). Note 2: Determination results outside the hydrogen sulfide content range in Table 2 are valid, but the precision will be affected. (Note: In Table 2, the repeatability index source-text extraction for method B (distillate fuel oil) is shown as "X01", and the repeatability index source-text extraction for method B (residual fuel oil) is shown as "X09", which is doubtful when inferred from the typical values in Table 3 and requires confirmation against the source standard (source-text extraction).)

• Table 3 Typical repeatability values (unit: mg/kg):

  Hydrogen sulfide content	Method A (distillate and residual fuel oils)	Method B (distillate fuel oil)	Method B (residual fuel oil)
  0.40	—	0.11	0.17
  0.60	0.25	0.15	0.22
  1.00	0.33	0.21	0.30
  1.50	0.42	0.28	0.38
  2.00	0.49	0.34	0.45
  3.00	0.61	0.45	0.57
  5.00	0.81	0.65	—
  10.0	1.18	1.05	—
  12.5	1.34	—	—
  15.0	—	—	—

  (Note: In Table 3, for method B (residual fuel oil), values are not provided in the available source at 5.00, 10.0, 12.5, 15.0; for method A, values are not provided in the available source at 15.0; for method B (distillate fuel oil), values are not provided in the available source at 12.5, 15.0. In Table 3, the column for method B (residual fuel oil) at 5.00 and above, the value source-text extraction appears to be misaligned in typesetting and requires confirmation against the source standard (source-text extraction).)

• Table 4 Typical reproducibility values (unit: mg/kg):

  Hydrogen sulfide content	Method A (distillate and residual fuel oils)	Method B (distillate fuel oil)	Method B (residual fuel oil)
  0.40	—	0.13	0.30
  0.60	0.34	0.27	0.39
  1.00	0.45	0.24	0.52
  1.50	0.56	0.32	0.67
  2.00	0.65	0.39	0.79
  3.00	0.82	0.52	1.01
  5.00	1.08	0.74	1.37
  10.0	1.59	—	2.08
  12.5	1.79	—	2.38
  15.0	—	—	2.66

  (Note: In Table 4, for method A, values are not provided in the available source at 15.0; for method B (distillate fuel oil), values are not provided in the available source at 10.0, 12.5, 15.0. In Table 4, for method B (distillate fuel oil), at 0.60, source-text extraction is shown as "0.27", which is non-monotonic compared with "0.24" at 1.00 and requires confirmation against the source standard (source-text extraction).)

11. Report

Chapter 15 Test report; the report shall contain at least the following information:

• Reference to this standard, and state whether method A or method B is used;
• Type and complete identification of the sample tested;
• Test results (see Chapter 13);
• Any deviation from the specified procedure by agreement or otherwise;
• Time and date of testing.

12. Reference Documents

• GB/T 4756 Petroleum liquids — Manual sampling (Chapter 2; dated/undated shall be implemented according to the original rules)
• GB/T 1.1-2009 (Foreword, drafting rules)

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 for Questions and Answers