SH/T 0753-2005 Determination of Chemical Group Composition of Lubricant Base Oils (Thin-Layer Chromatography)

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

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

• Standard number: SH/T 0753—2005
• Chinese title: Determination of Chemical Group Composition of Lubricant Base Oils (Thin-Layer Chromatography)
• English title: Standard test method for determination of chemical group composition in lube base oil by thin-layer chromatography
• Replacement relationship: not provided in the available source (the foreword does not list any replaced standard)
• Publication/implementation: published on 2005-04-11, implemented on 2005-09-01
• Issuing authority: National Development and Reform Commission of the People's Republic of China
• Technical committee: Sinopec Research Institute of Petroleum Processing
• Drafting organization: Sinopec Maoming Branch
• Appendix: Appendix A is a normative appendix

2. Scope of application and non-applicability

• 1.1 specifies a method for determining the chemical group composition of lubricant base oils by thin-layer chromatography.
• 1.2 is applicable to the determination of lubricant base oils produced by different processing technologies; applicable to the determination of lubricant distillates, refined oils and dewaxed oils from different processing stages; and also applicable to the determination of the chemical group composition of rubber extender oils and rubber process oils.
• 1.3 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 before use and determine applicable management systems.
• Non-applicability: not provided in the available source; no non-applicable objects are explicitly listed.

3. Method principle

• 4 Method summary: According to the thin-layer chromatography (TLC) separation principle, the sample is dissolved in toluene, developed on a silica gel rod with n-heptane and toluene developing solvents respectively, then detected by hydrogen flame (FID) scanning technology, and finally the mass fractions of the three components—saturated hydrocarbons, aromatic hydrocarbons, and polar compounds (resins + asphaltenes)—are calculated by the area normalization method.
• Term definitions (3):
  • 3.1 Saturated hydrocarbons saturates: under specified conditions, the substances that are developed with n-heptane on a silica gel rod from the origin to a development height of 50mm~100mm.
  • 3.2 Aromatic hydrocarbons aromatics: under specified conditions, after first developing the sample with n-heptane to 100mm and then developing with toluene, the substances on the silica gel rod from the origin to a development height of 20mm~50mm.
  • 3.3 Polar compounds (resins + asphaltenes) polar compounds: under specified conditions, the substances remaining near the origin on the silica gel rod after developing the sample with n-heptane and toluene respectively.

4. Reagents and materials (purity / preparation)

• 6.1 n-Heptane: analytical reagent, tested according to A.6 in Appendix A, and the transmittance should be greater than 85%. If it does not meet the requirement, treat it according to Appendix A.
• 6.2 Toluene: analytical reagent.
• 6.3 Fuel gas: hydrogen, purity greater than 99.99%.
• 6.4 Combustion-supporting gas: air.
• Appendix A Reagents and materials:
  • A.3.1 n-Heptane: analytical reagent.
  • A.3.2 Fine-pore silica gel: pore size 0.124mm–0.246mm. Note: after activating the silica gel at 150℃ for 5h–6h, cool it to room temperature in a desiccator before use.
• Developing solvent preparation (8.9):
  • 8.9.1 Add 70mL or 150mL n-heptane to a 150mL or 250mL developing tank as the first development solvent, and label it with the word n-heptane.
  • 8.9.2 Add 70mL or 150mL toluene to the other two 150mL or 250mL developing tanks as the second development solvent, and label them with the word toluene.
  • Note: n-Heptane and toluene are flammable and toxic reagents; operations should be carried out in a fume hood.

5. Instruments and equipment

• 5.1 Thin-layer chromatograph equipped with a hydrogen flame ionization detector.
• 5.2 Electronic data acquisition system: any data acquisition system and integrator used for quantification must meet or exceed the following minimum requirements:
  • 5.2.1 Can display chromatograms.
  • 5.2.2 Displays chromatographic peak area data.
  • 5.2.3 Retention time confirms the chromatogram.
  • 5.2.4 Calculation and use of response factors.
  • 5.2.5 Internal standard calculation and data display.
  • 5.2.6 Has the function of eliminating interference.
  • 5.2.7 Sufficient detection sensitivity for narrow peaks and broad peaks.
  • 5.2.8 Can perform perpendicular drop and tangent skim when needed.
  • 5.2.9 Can set and modify relevant parameters related to detection, such as threshold, scanning speed, paper speed, etc.
• 5.3 Silica gel rod: a quartz rod with a diameter less than 1mm and a total length of 150mm. Its outer layer is sintered from silica gel with a pore size of 6μm (requires confirmation against the source standard; the original text of source-text extraction is "6ym") and particles of 5μm (requires confirmation against the source standard; the original text of source-text extraction is "5pm") and an inorganic binder, and the silica gel portion is 135mm long.
  • Note 1: The silica gel rod should be stored in an environment free of solvents and contamination.
  • Note 2: The silica gel rod can be activated by blank scanning and reused.
• 5.4 Silica gel rod support frame.
• 5.5 Spotting plate.
• 5.6 Developing tank: 150mL or 250mL.
• 5.7 Purification tube filled with activated carbon in the combustion-supporting gas line.
• 5.8 Microsyringe: 1μL or 2μL (requires confirmation against the source standard; the original text of source-text extraction is "1g or 2L").
• 5.9 Ground-glass-stoppered test tube: 5mL, 10mL.
• 5.10 Pipette: 5mL.
• Appendix A Instruments:
  • A.4.1 Glass adsorption column: length about 90cm, inner diameter 5cm~8cm. The drawn-out lower end is about 5cm long with an inner diameter of 0.8cm.
  • A.4.2 Fixing frame.
  • A.4.3 UV-visible spectrophotometer: wavelength range 190nm~800nm. Or an instrument with equivalent performance.
  • A.4.4 Quartz absorption cell: optical path length 1cm.

6. Recommended operating conditions

• 7 Operating environment: indoor ambient temperature of 15℃~30℃ and humidity less than 65% are preferred.
• 8.1 Open the hydrogen valve and adjust its pressure to 0.3MPa, then open the hydrogen inlet valve of the thin-layer chromatograph.
• 8.2 Ignite the hydrogen burner.
• 8.3 Turn on the instrument power switch.
• 8.4 Turn on the hydrogen control switch and adjust the hydrogen flow rate to 160mL/min.
• 8.5 Turn on the combustion-supporting gas control switch and adjust the air flow rate to 2000mL/min.
• 8.6 Install the silica gel rod in the corresponding position on the silica gel rod support frame and secure it.
• 8.7 Place the silica gel rod support frame in the corresponding position of the thin-layer chromatograph and adjust it to level.
• 8.8 Baseline scan:
  • 8.8.1 Turn on the electronic data acquisition system and set the test parameters according to the instrument manual, such as attenuation, paper speed, scanning time, number of scans, end time, threshold, peak width, peak height, calculation method, etc.
  • 8.8.2 Start the instrument origin scanning switch to perform an origin scan on the silica gel rod.
  • 8.8.3 Set the blank scanning parameters according to 8.8.1, perform a blank scan, and observe the baseline smoothness.
  • Note: When the baseline is a straight line without spikes, the baseline can be considered smooth. Otherwise, repeat according to 8.8.2 and 8.8.3 until the baseline is smooth.

7. Sampling and sample preparation

• 9.1.1 Weigh 0.09g~0.10g of sample into a ground-glass-stoppered test tube, measure 4mL of toluene with a pipette to dilute, and shake well.
  • Note: If the sample contains water, dehydrate it before analysis.
• 9.1.2 Take out the silica gel rod support frame (8.8.3) and place it in the corresponding position on the spotting plate.
• 9.1.3 Use a microsyringe to draw 1μL (requires confirmation against the source standard; the original text of source-text extraction is "1") of the diluted sample, spot it evenly on the silica gel rod at the marked line position of the spotting plate in 5 portions, and air-dry at room temperature for 10min.
  • Note: The spotted spot should preferably not exceed 3mm.

8. Analysis procedure

• 9.2 Development of the sample:
  • 9.2.1 Place the silica gel rod (9.1.3) in a developing tank (8.9.1) containing n-heptane for development; the development height should preferably not exceed the scanning area of the hydrogen flame, generally controlled at 100mm±2mm.
  • 9.2.2 Take out the silica gel rod and air-dry at room temperature for 10min, place it in a developing tank (8.9.2) containing toluene for development; the development height is generally controlled at 20mm~50mm, then take out the silica gel rod and air-dry at room temperature for 20min.
  • Note: The operator may select different development heights according to the properties of the sample. This can avoid analytical errors caused by overlapping chromatographic peaks due to improper selection of development height.
• 9.3 Detection of the sample:
  • 9.3.1 Set the sample analysis parameters according to 8.8.1.
  • 9.3.2 Place the silica gel rod (9.2.2) in the corresponding position of the thin-layer chromatograph and adjust it to level.
  • 9.3.3 Start the normal scanning program of the instrument to scan. The data acquisition system acquires a chromatogram as shown in Figure 1.
  • Figure 1 Chromatogram (peak assignment): 1— chromatographic peak of saturated hydrocarbons; 2, 3, 4— chromatographic peaks of aromatic hydrocarbons; 5— chromatographic peak of polar compounds.
• Appendix A Treatment method for n-heptane:
  • A.1 Scope: This method is applicable to the removal of aromatic hydrocarbons from n-heptane.
  • A.2 Method summary: This method uses silica gel as an adsorbent; n-heptane passes through the silica gel adsorbent, and the aromatic hydrocarbons in the n-heptane are adsorbed by the silica gel, thereby achieving the purpose of dearomatizing n-heptane.
  • A.5 Test procedure: Plug the lower end of a glass adsorption column about 90cm long with an inner diameter of 5cm–8cm with cotton, load activated silica gel from the upper end all at once to three-quarters of the height of the glass adsorption column while tapping, the amount of silica gel loaded is about 1kg, continue tapping the glass adsorption column until the silica gel surface no longer drops. Clamp the glass adsorption column on the fixing frame, then add the n-heptane to be dearomatized; the liquid flow rate in the glass adsorption column can be controlled at 4mL/min–5mL/min.
  • A.6 Detection of n-heptane: The n-heptane flowing out of the glass adsorption column is detected with an ultraviolet-visible spectrophotometer, with an absorption cell path length of 1cm, using air as reference, at a wavelength of 270nm, and its transmittance shall be greater than 85%; if it does not meet the requirement, repeat the step of A.5 until the requirement is met.

9. Qualitative and Quantitative and Calculation Formulas

• 10 Division of saturated hydrocarbons, aromatic hydrocarbons, and polar compounds: According to the retention time on the chromatogram (RT), divide into three components: saturated hydrocarbons, aromatic hydrocarbons, and polar compounds. Among them, chromatographic peaks with RT not greater than 0.2min are saturated hydrocarbons; RT between 0.2min and 0.4min is aromatic hydrocarbons; and RT greater than 0.4min is polar compounds.
• 11 Calculation: The contents of saturated hydrocarbons, aromatic hydrocarbons, and polar compounds in the sample are calculated according to formula (1):
  • m = A_i / (A_1 + A_2 + A_5) × 100% …… (1)
  • Where:
    • m—— the content of the measured i component, % (mass fraction);
    • A_i—— the peak area of the measured i component;
    • A_1—— the peak area of saturated hydrocarbons in the measured sample;
    • A_2—— the peak area of aromatic hydrocarbons in the measured sample;
    • A_5—— the peak area of polar compounds in the measured sample.
  • Note: The original formula source-text extraction contains noise (“m=A+A2+A5×100%”); the above denominator terms are restored according to the original definitions of A_1, A_2, and A_5, and requires confirmation against the source standard (source-text extraction).

10. Precision

• Judge the reliability of test results according to the following provisions (95% confidence level).
• Note: This precision was obtained from statistical tests using 10 samples in 5 laboratories from year 2000 to year 2001, and the test results were processed and analyzed according to GB/T 6683.
• 12.1 Repeatability (r): The difference between two results obtained by the same operator in the same laboratory using the same instrument on the same sample according to the same test method shall not exceed the repeatability value in Table 1.
• 12.2 Reproducibility (R): The difference between two results obtained by different operators in different laboratories using different instruments on the same sample according to the same test method shall not exceed the reproducibility value in Table 1.
• Table 1 Precision (Unit: % (mass fraction)):

• Note: X represents the arithmetic mean of two measurement results.

11. Report

• 13 Report: Take the arithmetic mean of two repeated measurement results as the measurement result. Report the result to two decimal places.

12. Referenced Documents

• GB/T 6683 Determination method for precision data of petroleum product test methods (GB/T 6683-1997, ISO 4259:1992, NEO)
  • Note: The original text is “NEO”, suspected to be “NEQ”, requires confirmation against the source standard (source-text extraction).

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