NB/SH/T 0474-2010 Determination of Diluted Gasoline Content in In-Service Gasoline Engine Oils Gas Chromatography

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Card type: Test method

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

• Standard number: NB/SH/T 0474—2010
• Chinese full name: Determination of Diluted Gasoline Content in In-Service Gasoline Engine Oils Gas Chromatography
• English name: Standard test method for gasoline diluent in used gasoline engine oils by gas chromatography
• Replacement relationship: replaces SH/T 0474—2000 "Determination of Diluted Gasoline Content in Used Gasoline Engine Oils (Gas Chromatography)"
• Adoption relationship: modified adoption of ASTM D3525-04 "Determination of Diluted Gasoline Content in In-Service Gasoline Engine Oils (Gas Chromatography)"
• Publication/implementation: published on 2011-01-09, implemented on 2011-05-01
• Issuing authority: National Energy Administration
• Custodian: Subcommittee on Lubricating Oil Drain Criteria of the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC280/SC6)
• Proposed by: China Petrochemical Corporation
• Revision unit: Lubricant Research and Development (Shanghai) Center of China Petroleum & Chemical Corporation
• Participating revision unit: Dalian Lubricant Research and Development Center of PetroChina Company Limited
• Main drafters: Yang Lijun, Lü Wenji, Yu Bing
• Version history: first published in 1992, first revision in 2000, this is the second revision

Main differences from ASTM D3525-04 (original foreword):

• Difference in test conditions: initial column temperature changed from 30 ℃ to 40 ℃; initial peak retention time changed from 15 s or more to 10 s or more.
• Temperature programming changed from first-order temperature programming to second-order temperature programming, and the final temperature changed to 290 ℃.
• Vaporization chamber temperature changed from 255 ℃ to 300 ℃.
• Modified the carrier gas flow rate when using a capillary column.
• Deleted the requirement for capillary column resolution.
• Cancelled the normative reference documents.
• Cancelled the discussion content in the terms chapter.
• Changed the purity of the reagents n-tetradecane, n-hexadecane and n-octane to chromatographic purity.
• Replaced the calculation formula of single-point calibration in the original standard with the formula of multi-point calibration curve.
• The expressions of repeatability and reproducibility were modified to the customary expressions of our country.

Main differences from SH/T 0474—2000 (original foreword):

• The standard name was changed to "Determination of Diluted Gasoline Content in In-Service Gasoline Engine Oils Gas Chromatography".
• Added a method for testing diluted gasoline content using a capillary column.
• Adopted the calibration curve quantitative method instead of the formula method (single-point calibration) to calculate gasoline content.
• Detector temperature changed from the original 290 ℃ to 300 ℃.

2. Scope of application and non-applicability

• 1.1 This standard specifies a method for the determination of diluted gasoline content in in-service gasoline engine oils by gas chromatography.
• 1.2 There is no limit to the range of diluted gasoline content of the samples measured, as long as the sample and internal standard content are within the detection range of the gas chromatograph.
• 1.3 This standard is limited to the use of a gas chromatograph equipped with a hydrogen flame ionization detector and having a temperature programming function. Note: The use of other detectors and configurations has also been reported, but the precision of this method is only applicable to the specified instrument.
• 1.4 For gelled gasoline engine oils, this standard has not yet conducted sufficient investigation of its repeatability and reproducibility to confirm its feasibility. Gelled gasoline engine oil refers to oil that has denatured under static conditions but can recover its fluidity under slight stirring.
• 1.5 This standard uses International System of Units (SI) units.
• 1.6 This standard involves certain safety issues related to the use of the standard. However, it is not intended to address all safety issues. Therefore, users should establish appropriate safety and protective measures and determine applicable management systems before using this standard.

3. Method principle

The sample is analyzed by gas chromatography, and n-tetradecane of known percentage content is added as an internal standard to determine the mass fraction of gasoline in the gasoline engine oil. A calibration curve is established in advance, that is, the ratio of the response values of gasoline to n-tetradecane is plotted against the mass percentage of gasoline in the lubricating oil mixture containing a constant amount of internal standard. The mass fraction of gasoline in the sample is determined by the calibration curve or calculation formula.

(Chapter 4 Significance and use: During normal operation of an engine, a certain amount of gasoline may be diluted into the engine lubricating oil. However, an excessively large diluted gasoline content may indicate a problem with engine performance. This standard provides a method for detecting diluted gasoline content, which helps users predict engine performance so as to take appropriate measures.)

4. Reagents and materials (purity / preparation)

• 6.1 Unless otherwise specified, all reagents used in the test are of analytical purity. Other grades may also be used as long as the reagent purity can ensure that the determination precision is not reduced.
• 6.2 Stationary liquid: methyl silicone resin and other stationary liquids that can meet the requirements of this standard for chromatographic column characteristics.
• 6.3 Support: appropriately sized crushed firebrick and diatomaceous earth are used as packing column supports, and their particle size and stationary liquid coating amount are based on obtaining the best resolution and analysis time. Generally refers to (requires confirmation against the source standard source-text extraction), particle size range 60 mesh to 100 mesh, coating amount 8% to 10% (requires confirmation against the source standard source-text extraction).
• 6.4 Carrier gas: helium or nitrogen, purity not less than 99.90% (mole fraction). It is recommended to use molecular sieves or other suitable substances to further purify the carrier gas to remove moisture, oxygen and hydrocarbon impurities. The gas source pressure must ensure the stability of the carrier gas flow rate. Warning: nitrogen and helium are compressed gases.
• 6.5 Hydrogen: high purity, not less than 99.99% (mole fraction), combustion gas for the hydrogen flame ionization detector. Warning: hydrogen under high pressure (requires confirmation against the source standard source-text extraction).
• 6.6 Air: compressed air, combustion-supporting gas. Warning: compressed air has high pressure and supports combustion.
• 6.7 n-Tetradecane, chromatographic purity. Warning: flammable liquid, vapor harmful.
• 6.8 n-Hexadecane, chromatographic purity. Warning: flammable liquid, vapor harmful.
• 6.9 n-Octane, chromatographic purity. Warning: flammable liquid, vapor harmful.
• 6.10 Carbon disulfide. Warning: carbon disulfide is extremely volatile.
• 6.11 Calibration mixture: prepare (the original text is truncated at source-text extraction here, the specific preparation steps are not provided in the available source) and cover the range of gasoline content to be measured.

5. Instruments and equipment

• 5.1 Gas chromatograph: should have the following characteristic parameters.
  • 5.1.1 Detector: This standard uses a hydrogen flame ionization detector. Under the test conditions specified in this standard, the peak height of the detector for 1% n-C14 (requires confirmation against the source standard source-text extraction, original text as n-Ca) should not be less than 40% of the full scale of the data acquisition device, and at this sensitivity, the stability of the detector must achieve an extreme drift per hour of not more than 1% of full scale. It must be able to work continuously at the maximum operating temperature of the chromatographic column. The connection between the chromatographic column and the detector must ensure that there is no low (requires confirmation against the source standard source-text extraction) region (cold spot).
  • 5.1.2 The column temperature programmer should have a linear temperature programming function, and the range of temperature programming must ensure the retention time of the initial chromatographic peak (requires confirmation against the source standard source-text extraction), so that the internal standard is completely eluted, and the reproducibility of the retention time is not more than 1 s (requires confirmation against the source standard source-text extraction, original text as 18).
  • 5.1.3 Injection system: the function of continuous temperature control at the maximum operating temperature of the chromatographic column, or the use of an on-column injection port with a temperature programming function and capable of reaching (requires confirmation against the source standard source-text extraction) temperature quality. It should ensure that there is no region of low column temperature (cold spot) in the connection between the chromatographic column and the injection port.
• 5.2 Data acquisition system: should have the function of (requires confirmation against the source standard source-text extraction) chromatographic peak area, and can be an electronic integrator or computer with chromatographic data processing functions.
  • 5.2.1 The chromatographic software of the integrator or computer system must have a mode for calculating the retention time and area (peak detection mode) of chromatographic elution peaks, and process electronic signals within the linear range of the detector (e.g., 1V, 10V). The system preferably has the function of subtracting the blank baseline. The integration system can realize automated operation and obtain the best precision. The gas chromatography operating software can store the mathematical model of the baseline in memory, so that in subsequent sample analysis, the baseline is automatically subtracted from the detector signal to compensate for baseline deviation. Some integrators also have the function of automatically storing and automatically subtracting the baseline from the sample spectrum.
• 5.3 The chromatographic column used (requires confirmation against the source standard source-text extraction) original text as (requires confirmation against the source standard source-text extraction), must ensure that under the test conditions, the sample components can be obtained in order of increasing boiling point (requires confirmation against the source standard source-text extraction). The packed column resolution (requires confirmation against the source standard source-text extraction) is not less than 3 and not more than 8 (requires confirmation against the source standard source-text extraction), because this method requires a stable baseline, so it is necessary to compensate for chromatographic column bleed, detector temperature control, carrier gas flow rate stability and instrument drift.
• 5.4 Controller: The gas chromatograph must be equipped with a (requires confirmation against the source standard source-text extraction) flow controller to keep the carrier gas flow rate constant within the operating temperature range of the chromatographic column, with fluctuation within the range of ±1%. The pressure of the gas chromatograph (requires confirmation against the source standard source-text extraction) must be sufficiently large to compensate for the increase in back pressure in the (requires confirmation against the source standard source-text extraction) region when the column temperature rises. For the columns listed in Table 1, an inlet pressure of 550 kPa can meet the requirements.
• 5.5 Injector
  • 5.5.1 A 10 μL microsyringe is commonly used for injection.
  • 5.5.2 It is preferred to use an automatic injector to ensure the repeatability of the injection volume, and the injector should be synchronized with the operation of the gas chromatograph.
  • 5.5.3 Sample bottle, a bottle with a septum, the specification is compatible with the injector.

6. Recommended operating conditions

Table 1 Typical chromatographic operating conditions

Note: When using an inlet with programmed temperature capability, the carrier gas flow rate may be appropriately increased.

Clauses related to other operating conditions:

• 7.3 Gas chromatography and related equipment: Set operating conditions according to the instrument (requires confirmation against the source standard source-text extraction) manual; typical operating conditions are given in Table 1.
• 7.3.1 When using a hydrogen flame detector, deposits formed on the detector by silicone rubber or stationary phase (requires confirmation against the source standard source-text extraction) products must be periodically removed to avoid affecting the detector response characteristics.
• 7.3.2 If the inlet heating temperature exceeds 300 ℃, then a blank analysis must be performed after each replacement of a new inlet septum to eliminate interference signals caused by septum bleed. At the sensitivity typically used in this standard, allowing the septum to age for several hours at the inlet operating temperature can reduce this interference. It is recommended to replace the septum after completing the analysis task rather than before starting the analysis.

7. Sampling and Test Sample Preparation

Chapter 8 Sample preparation:

• Using a 1 mL syringe, inject 0.5 mL of test sample into a sample vial, weigh the test sample, then inject 10 μL n-C14 of internal standard, weigh the internal standard, and record.
• If the test sample is relatively viscous at room temperature and difficult to inject, a verified suitable dilution solvent such as 0.5 mL n-C10 may be added, cap the vial and shake for at least 2 min to ensure the sample is homogeneous.
• If a capillary column is used, the sample must be further diluted CS2 times with 10.
• Note: When testing samples with a capillary column, if the peak area of CS2 (experimentally proven that CS2 responds on the hydrogen flame detector) is larger than the peak area of gasoline, the dilution factor of CS2 may be reduced or another dilution solvent such as n-hexadecane may be used.

8. Analytical Procedure

Chapter 7 Instrument preparation:

• 7.1 Column preparation
  • 7.1.1 Packed column may be prepared as follows (requires confirmation against the source standard source-text extraction):
    1. Connect the column to the inlet (requires confirmation against the source standard source-text extraction);
    2. (requires confirmation against the source standard source-text extraction) thoroughly purge with carrier gas (requires confirmation against the source standard source-text extraction) the mixture of gas source and lubricating oil; the mixture should be similar to the type of sample being analyzed;
    3. (requires confirmation against the source standard source-text extraction) aging (requires confirmation against the source standard source-text extraction) 80 m (requires confirmation against the source standard source-text extraction); disconnect the column from the detector, set the carrier gas (requires confirmation against the source standard source-text extraction) the loss is very low, but aging treatment is still required, flow rate. Purge with carrier gas at room temperature (requires confirmation against the source standard source-text extraction).
  • 7.2 Resolution
    • 7.2.1 (not provided in the available source)
    • 7.2.2 From the consistency of the results of n-C14 (requires confirmation against the source standard source-text extraction), according to formula (1) (requires confirmation against the source standard source-text extraction) of the mixture, to determine the column (requires confirmation against the source standard source-text extraction) specified experimental procedure to obtain the chromatogram.
      • Formula (1): R = ... (original text source-text extraction truncated)
      • Where: R— (requires confirmation against the source standard source-text extraction); d— (requires confirmation against the source standard source-text extraction); d— (requires confirmation against the source standard source-text extraction); Y— (requires confirmation against the source standard source-text extraction); retention time of n-C14; peak at the baseline of the n-C14 peak (requires confirmation against the source standard source-text extraction); peak at the baseline of the n-C14 peak (requires confirmation against the source standard source-text extraction).

Chapter 9 Calibration:

• 9.1 Analyze each calibration mixture prepared in 6.11 according to the procedure described in 8 and 10, recording the total area of the gasoline response and the area of the n-C14 response in each calibration mixture.
• 9.2 Calculate the ratio R for each calibration mixture according to formula (2):
  • R = A/B ... (2)
  • Where: A— total area of gasoline peaks; peak area of B—n-C14.
• 9.3 Plot the ratio R against the mass percentage of gasoline prepared according to 6.11 to obtain the calibration curve.

Chapter 10 Experimental Procedure:

• 10.1 Set the chromatographic operating conditions according to Table 1.
• 10.2 Inject a certain volume of test sample into the gas chromatograph.
  • 10.2.1 Note to select an appropriate sample injection volume so that all sample peaks do not exceed the linear range of the detector. For packed columns, the injection volume is 0.2 μL～1.0 μL; for capillary columns, for sample solutions after dilution by a factor of 10, the injection volume is 0.1 μL～0.2 μL.
• 10.3 After injecting the test sample, immediately start the programmed temperature ramp; the ramp rate depends on the separation required by Table 1 or 5.3. The data acquisition system must be started synchronously with the sample injection.
• 10.4 When the peak of n-C14 has eluted, integration of peak areas may be stopped; the peak area of gasoline engine oil is not required for quantification.
• 10.5 Backflushing or raising the system temperature may be used to elute heavy components.

9. Qualitative and Quantitative Analysis and Calculation Formulas

Chapter 11 Calculation:

• 11.1 Record the area corresponding to the gasoline peak and the area corresponding to the n-C14 peak from 0 min to before the elution of n-C14.
• 11.2 Determine the mass percentage of gasoline in the sample from the R value and the pre-established calibration curve; if the chromatography processing software does not have this function, calculate according to formula (3) or (4):
  • Formula (3): (original text source-text extraction truncated)
  • Formula (4): Cs = Rs × (C2 - C1) / (R2 - R1) (original text source-text extraction truncated, requires confirmation against the source standard)
  • Where:
    • Cs— diluted gasoline content in the sample;
    • C1— diluted gasoline content in the calibration mixture, corresponding to R1, calculated by formula (2);
    • C2— diluted gasoline content in the calibration mixture, corresponding to R2, calculated by formula (2);
    • Rs— ratio of the gasoline peak area to the n-C14 peak area in the sample;
    • R1— ratio of the gasoline peak area to the n-C14 peak area for the calibration mixture with a lower diluted gasoline content than the sample;
    • R2— ratio of the gasoline peak area to the n-C14 peak area for the calibration mixture with a higher diluted gasoline content than the sample.
  • Note: When abnormal peaks appear on the chromatogram, it indicates that degradation processes may exist; the calibration curve can be used to correct the diluted gasoline content.

10. Precision

Chapter 13 Precision and Bias:

• 13.1 Judge the reliability of test results according to the following provisions (95% confidence level):
  • 13.1.1 Repeatability: The difference between two consecutive test results obtained by the same operator, using the same instrument, according to the same test method, on the same test sample shall not exceed 0.28% (mass fraction).
  • 13.1.2 Reproducibility: The difference between two single, independent test results obtained by different operators, in different laboratories, using different instruments, with the same method, on the same test sample shall not exceed 1.64% (mass fraction).
• 13.2 Bias: Because no suitable reference material is available, the bias of the method cannot be evaluated.

11. Report

Chapter 12 Report:

• 12.1 Report the gasoline content in the sample in the following form, with the result accurate to 0.01%:
  • Gasoline content: ×x.× ×% (mass fraction)

12. Referenced Documents

The original foreword states: normative referenced documents have been deleted. No list of normative referenced documents is found in the main text.

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