SH/T 0607-1994 Determination of group composition of rubber filling oils, process oils and petroleum-derived oils (clay-silica gel adsorption chromatography)

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

• Standard number: SH/T 0607-94 (confirmed in 2004)
• Chinese full name: Determination of group composition of rubber filling oils, process oils and petroleum-derived oils (clay-silica gel adsorption chromatography)
• English name: not provided in the available source
• Replacement relationship: not provided in the available source
• Adoption relationship: equivalent adoption of the American Society for Testing and Materials standard ASTM D2007-91 "Standard Method for Determination of Group Composition of Rubber Filling Oils, Process Oils and Petroleum-Derived Oils by Clay-Silica Gel Adsorption Chromatography"
• Approval/implementation: approved by China Petrochemical Corporation 1994-10-07, implemented on 1995-07-01
• Technical committee: technical coordination by the Research Institute of Petroleum Processing
• Drafting unit: responsible drafting by Dalian Petrochemical Company
• Main drafter: Du Jizhou

2. Scope of application and non-applicability

• This standard specifies a method for determining the group composition of rubber filling oils, process oils and petroleum-derived oils by clay-silica gel adsorption chromatography.
• Applicable to the determination of group composition of samples with an initial boiling point greater than 260℃.
• For samples with n-pentane insolubles greater than 0.1%, this standard cannot be used directly; the n-pentane insolubles in the sample must first be removed before determination, but the precision will be reduced.

3. Method principle

After the sample is diluted with solvent, it is added to an adsorption column packed with adsorbent. It is eluted with an eluent, and the effluent is collected as specified. The solvent in the effluent is removed, the residue is weighed, and the contents of saturated hydrocarbons and polar compounds are calculated. Aromatics are calculated by difference, or determined by desorption through a silica gel column and evaporation of toluene.

4. Reagents and materials (purity / preparation)

4.1 Materials

• Calcium chloride: anhydrous granules.
• Clay: 30～60 mesh. Its quality can be checked by the test method in Appendix A. The azobenzene activity value of the clay should be between 30～35.
• Silica gel: 30～200 mesh (requires confirmation against the source standard (source-text extraction), original text is "30[unreadable separator]20(】mesh"), macroporous. Before use, activate in an oven at 190℃ for 4h.

4.2 Reagents

• Acetone: analytical reagent.
• n-Pentane: chemical reagent.
• Toluene: analytical reagent.
• Toluene-acetone mixed liquid: volume ratio 1:1 (see 6.1.7).
• Azobenzene solution [1%(m/m)] (Appendix A): dissolve 10g±0.001g (requires confirmation against the source standard (source-text extraction), original text is "log[unreadable sign]0.00[unreadable character]") of chemically pure azobenzene in 990g of isooctane. Note: ① Azobenzene may be a carcinogen; ② Isooctane is flammable.

5. Instruments and equipment

• Beaker: 100mL.
• Clay-silica gel adsorption column: see Figure 1. The adsorption column is made of glass, and the upper and lower columns are connected by a 24/40 ground joint.
• Conical flask: 250, 500mL.
• Graduated cylinder: 100, 250, 500mL.
• Funnel: ordinary glass funnel.
• Separatory funnel: 500mL.
• Heating plate: adjustable power, explosion-proof, and capable of heating in the range of 100～105℃.
• Extraction apparatus: see Figure 2.
• Oven.
• Azobenzene adsorption column (Appendix A): made of glass, composed of two standard glass tubes with outer diameters of 12.0mm and 6.0mm respectively and an approximately 125mL liquid reservoir on top. The top of the column should have a ground glass joint (see Figure A1 for details).
• Graduated cylinder (Appendix A): 5 or 10mL, with graduations of 0.1mL.
• Gas or air pressure system (Appendix A): adjustable pressure.
• Spectrophotometer (Appendix A): with a measurement wavelength of 446nm, equipped with a 1mm (or 0.5mm) thick absorption cell.

6. Recommended operating conditions

• Clay azobenzene activity value: 30～35.
• Silica gel activation: activate in an oven at 190℃ for 4h.
• Solvent evaporation heating plate surface temperature: 100～105℃.
• Toluene reflux rate: 10mL/min±2mL/min, reflux 2h (6.2.2).
• Azobenzene adsorption column flow rate: 1mL/min (Appendix A5.5).
• Azobenzene adsorption column normal pressure: 6.7×10³～2.0×10⁴Pa (requires confirmation against the source standard (source-text extraction), original text is "6.7x 1[unreadable characters]2. O x I[unreadable character]Pa").

7. Sampling and sample preparation

• Weigh the corresponding sample amount according to the following polar compound content ranges:

• Note: If the polar compound content range in the sample is not known in advance, use a 10g±0.5g sample.
• Dilute the sample with 25mL n-pentane to completely dissolve it. At this time, no precipitate or floc should appear. If precipitate or floc appears, the asphaltenes should be removed according to the procedure in Appendix B, but the precision no longer applies. It is important that the polar compound content obtained cannot be greater than the polar compound content corresponding to the sample amount specified above. Because at these concentrations, the ability of the clay to retain polar components is limited. If the determination result exceeds the above specification, repeat the test with a smaller sample amount. The separation between polar compounds and aromatics is affected by the sample amount; using different sample amounts will give different results.
• Note: For viscous samples, diluting the sample with 25mL cyclohexane does not affect the test results, but a small amount of asphaltenes cannot be detected.

8. Analysis procedure

8.1 Group separation

• 6.1.1 Column packing: The bottoms of both the upper and lower columns are tightly plugged with degreased cotton (an adsorption column with a filter plate may also be used). Add 100g of clay adsorbent to the upper column. Add 200g of silica gel to the lower part of the lower column, and add 50g of clay to the upper part. Tap gently at different positions on each column with a tapping rod with soft rubber until the adsorbent surface no longer settles. Then, loosely place some glass wool (about 25mm thick) on the surface of the clay in the upper column to prevent the clay surface from being washed into depressions when the eluent is added. Connect the two columns.
• 6.1.2 Weigh the sample amount according to the table in Section 7.
• 6.1.3 Dilute the sample with 25mL n-pentane to completely dissolve it. At this time, no precipitate or floc should appear. If precipitate or floc appears, the asphaltenes should be removed according to the procedure in Appendix B.
• 6.1.4 Pre-wet the clay with 25mL n-pentane. After the n-pentane has completely entered the clay, add the diluted sample. Rinse the beaker several times with a small amount of n-pentane, and pour the rinse liquid into the column. After all the sample has entered the clay layer, rinse the inner wall of the column where a small amount of sample remains with n-pentane. The sample and n-pentane should be added to the column through a wide-neck funnel with a diameter of 65mm (the funnel can be placed on top of the column). During the operation, air must not enter the clay layer.
• 6.1.5 When the rinse liquid has completely entered the clay layer, add n-pentane to the column and keep the top of the clay layer intact. Rinse the saturated hydrocarbon components of the sample in the adsorption column, and collect 280mL±10mL of n-pentane effluent below the column with a graduated cylinder.
• 6.1.6 Disconnect the combined column and continue rinsing the upper adsorption column with n-pentane. Control the amount of n-pentane added so that an appropriate liquid level is maintained above the clay layer. When 150mL of effluent has been collected in the graduated cylinder, the liquid level in the adsorption column should be 25mm. At this point, stop adding n-pentane and let the liquid flow out of the column. Approximately 200mL of effluent should be collected in the graduated cylinder. If the aromatic content is to be determined by difference, the n-pentane effluent obtained in this step should be discarded. If aromatics are to be recovered, this 200mL effluent should be added to the aromatic solution obtained from the silica gel column when evaporating the solvent.
  • Note: The clay layer must be rinsed with sufficient n-pentane to ensure that the aromatics are rinsed clean.
• 6.1.7 Add a toluene-acetone mixed liquid with a volume ratio of 1:1 to the upper adsorption column. Collect the effluent in a 500mL separatory funnel. Collect 250mL of effluent, or collect until the effluent is colorless.
• 6.1.8 Shake the separatory funnel several times to deposit water, then let it stand for 5min, and drain off the water. Add about 50g of anhydrous calcium chloride to the separatory funnel, stopper it, shake for 30s, opening the stopcock to release pressure while shaking, then let it settle for at least 10min.
• 6.1.9 Filter the above components with filter paper, and collect the filtrate in a 500mL conical flask. Wash the separatory funnel with about 25mL of n-pentane, then wash the filter paper with 10～15mL of n-pentane, and add the rinse liquid to the conical flask.
  • Note: All transfers of organic solvents in the separatory funnel must be covered to avoid introducing water during transfer, which would deposit in the calcium chloride.

8.2 Desorption of aromatics

• 6.2.1 If the separation method is used to determine aromatics, the silica gel column that has collected 280mL±10mL of n-pentane should be installed in the extraction apparatus according to Figure 2 for extraction.
• 6.2.2 Add 200mL±10mL of toluene to a 500mL round-bottom flask, and reflux at a rate of 10mL/min±2mL/min for 2h.
  • Note: The toluene reflux rate can be measured by valve A in Figure 2 and collecting 1min in a graduated cylinder.
• 6.2.3 After refluxing, open valve A and release about 50mL of toluene. The remaining solution mixed with the 200mL n-pentane effluent obtained in 6.1.6 is the aromatic recovery liquid.

8.3 Evaporation and recovery of solvent

• 6.3.1 Take half of the volume of the effluent (saturated hydrocarbons from 6.1.5, aromatics from 6.1.6 and 6.2.3, polar compounds from 6.1.9) and inject them into three weighed conical flasks respectively. Then place them on an electric heating plate with a surface temperature of about 100～105℃ to evaporate and recover the solvent. When the volume is reduced to about one quarter, continue adding the above effluent and evaporate. A nitrogen stream can be used to protect the liquid surface; the nitrogen stream should neither be too strong nor should the nozzle contact the liquid surface. The conical flask containing the effluent should be rinsed clean with n-pentane and poured into the weighed conical flask for evaporation.
• 6.3.2 After all the solvent has evaporated to dryness, wait for the conical flask to cool to room temperature, and weigh the conical flask at intervals of every 10min. When the difference between two consecutive weighings is less than 10mg, the solvent is considered to have evaporated to dryness.

9. Qualitative and quantitative determination and calculation formulas

The saturated hydrocarbon content X₁ [%(m/m)], aromatic content X₂ [%(m/m)], and polar compound content X₃ [%(m/m)] in the sample are calculated according to formulas (1)～(4).

• X₁=(m₂/m₁)×100 ………………(1)
• X₂=(m₃/m₁)×100 ………………(2)
• X₃=(m₄/m₁)×100 (for 10g sample) ………………(3)
• X₃=[0.88×(m₄/m₁)]×100 (for 5g sample) ………………(4)

Where:

• m₁—mass of sample used, g;

• m₂—mass of residue after evaporation of n-pentane effluent, g;

• m₃—mass of residue after evaporation of toluene effluent from the lower column and n-pentane rinse from the upper column (200mL), g;

• m₄—mass of residue after evaporation of toluene-acetone effluent, g.

• 7.2 The total amount of all recovered components shall be greater than or equal to 97%(m/m) of the amount of sample added; otherwise the test is invalid and shall be re-tested.

  • Note: For rubber extender oils, the factors in calculation formula (4) maintain continuity of results over a wide range of polar compound content.

• 7.3 If aromatics are not desorbed, the n-pentane insolubles, saturated hydrocarbon content, and polar compound content calculated in clause 7.1 may be used to calculate the aromatic content X₄[%(m/m)] according to formula (5):

  • X₄=100-(X₁+X₃) ………………(5)
  • Where: X₁—percentage content of saturated hydrocarbons, [%(m/m)]; X₃—percentage content of polar compounds, [%(m/m)].

10. Precision

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

10.1 Repeatability

The difference between two results obtained by the same operator in repeated determinations shall not exceed the value in Table 1.

Table 1 Repeatability values %(m/m)

10.2 Reproducibility

The difference between two results obtained by different operators in different laboratories shall not exceed the value in Table 2.

Table 2 Reproducibility values %(m/m)

Note: The above precision is obtained when samples from which n-pentane insolubles have been removed before testing (Appendix B) are not included.

10.3 Appendix A Precision (Clay-benzeneazo activity test method)

• Repeatability: The difference between two results obtained by the same operator shall not exceed 1mL.
• Note: If the difference between two repeated determination results is greater than 1mL, a third determination shall be made, and the average of the three values shall be taken as the final result.

10.4 Appendix B Precision (n-Pentane insolubles removal method)

• Because there were too few round-robin test samples to meet the requirements of the laboratory test method precision test, however, it may be roughly specified as repeatability: 1.3%(m/m), reproducibility: 7.8%(m/m).

11. Report

• 9.1 Take the arithmetic mean of two repeated determination results as the determination result, and round to two decimal places.
• 9.2 The test report shall include the following contents:
  • 9.2.1 Sample name.
  • 9.2.2 Percentage content of saturated hydrocarbons, aromatics, and polar compounds.
  • 9.2.3 Aromatic content determination method: desorption method or subtraction method.
  • 9.2.4 If aromatics are obtained by desorption, the recovery shall be given.

12. Referenced documents

• ASTM D2007-91 “Standard Method for Determination of Rubber Extender Oils, Process Oils, and Petroleum-Derived Oils by Clay-Silica Gel Adsorption Chromatography” (equivalent adoption)
• Appendix A: Clay-benzeneazo activity test method (supplementary document)
• Appendix B: n-Pentane insolubles removal method (reference document)

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.

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