NB/SH/T 0826-2010 Determination of Volatility of Engine Oils by Capillary Gas 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: NB/SH/T 0826-2010
• Chinese title: Determination of Volatility of Engine Oils by Capillary Gas Chromatography
• English title: Standard test method for estimation of engine oil volatility by capillary gas chromatography
• Replacement relationship: This standard is first published (not provided in the available source regarding replacement of other standards)
• Adoption relationship: Modified adoption of ASTM D6417-03 "Determination of Volatility of Engine Oils by Capillary Gas Chromatography", redrafted according to ASTM D6417-03
• Main differences from ASTM D6417-03: The referenced standards adopt the current national standards of our country; where our country has no corresponding national standard, it is explained in the text and its standard is no longer referenced; chromatographic conditions using nitrogen as carrier gas are added
• Publication/implementation: published on 2010-05-01, implemented on 2010-10-01
• Proposing unit: China Petrochemical Corporation
• Technical committee: Sinopec Research Institute of Petroleum Processing
• Drafting unit: Sinopec Research Institute of Petroleum Processing
• Main drafters: Jin Ke, Yang Haiying

2. Scope of application and non-applicability

• 1.1 specifies a method for determining the volatility of engine oils using a capillary gas chromatograph.
• 1.2 is applicable to the determination of the volatility of engine oils at 371 ℃; it is also applicable to the determination of the volatility of oils at any temperature point between 126 ℃~371 ℃. It is applicable to lubricating base oil samples whose initial boiling point is higher than 126 ℃ or whose first calibration component has a boiling point lower than the initial boiling point of the sample, and whose final boiling point is lower than 615 ℃ or whose last n-alkane in the calibration mixture has a boiling point higher than the final boiling point of the sample. By using certain instruments and chromatographic columns, it is possible to extend the scope of application of the method.
• 1.3 adopts the principle of the simulated distillation method.
• 1.4 can be used for lubricating base oils and finished lubricating oils containing composite additives. Composite additives usually contain high-molecular-weight non-volatile components that cannot flow out of the chromatographic column under the experimental conditions of this method. The calculation formula of this method assumes that all components in the sample can flow out of the chromatographic column and are detected with the same response factor; if non-volatile additives are present in the sample, this assumption does not hold, and in this case the results obtained will have a large deviation compared with the SH/T 0695 determination method that uses an internal standard to determine non-eluted substances; therefore, this method directly expresses volatility as the area percentage of the sample.
• 1.5 adopts International System of Units (SI) units.
• 1.6 This standard does not put forward suggestions for all safety issues involved; before use, users should establish appropriate safety and protection measures and formulate corresponding management systems.
• 5.2 This test method is intended to be used as an alternative method to the SH/T 0059 method, the SH/T 0695 method, and the DIN 51581 method for determining the volatility of engine oils. The data obtained from this test method are not directly equivalent to the SH/T 0059 method. For additives (polymers) that cannot all flow out of the gas chromatographic column or heavy base oils that cannot all flow out of the chromatographic column, the oil volatility results calculated by this test method may have deviations; for non-hydrocarbon synthetic lubricating oils, the results of this test method may also have no correlation with other oil volatility determination methods.
• 5.3 This test method can be used for lubricating oil products not covered by the scope of other simulated distillation test methods (such as the SH/T 0558 method).

3. Method principle

• 4.1 The method uses a non-polar open-tubular capillary gas chromatographic column to allow the hydrocarbon components in the sample to elute in order of increasing boiling point.
• 4.2 The sample is diluted with solvent to reduce viscosity and then introduced into the gas chromatograph, but at least one laboratory analyzing the sample shall use the pure sample without solvent dilution. The precision of the method is calculated based on diluted oil samples; if the laboratory chooses to use pure sample injection, it should first determine that similar results can be obtained. Sample vaporization may use either independent heating at the injection point or heating synchronized with the column temperature.
• 4.3 A repeatable linear programmed temperature rate is used to raise the chromatographic column temperature, so that hydrocarbon components elute in order of increasing boiling point. A hydrogen flame ionization detector (FID) is used to quantitatively determine the eluate, and the detector integral signal of continuous retention time segments during the analysis is recorded as area slices.
• 4.4 Within the span of the test method scope (n-C8~n-C100), the retention times of known hydrocarbons are determined and correlated with their boiling point temperatures. Using the calibration relationship constructed from n-alkanes, linear regression is used to calculate the retention time at 371 ℃. The volatility of the oil at 371 ℃ is calculated from the cumulative corrected area of the sample measured at the retention time at 371 ℃.

4. Reagents and materials (purity / preparation)

• 7.1 Carrier gas: helium, nitrogen (or hydrogen). It is recommended to add a purifier, using molecular sieves or other removal agents to remove water, oxygen, and hydrocarbons. Adjust the pressure to ensure a constant carrier gas flow rate. Warning: compressed gas under high pressure; hydrogen under high pressure is a very flammable gas.
• 7.2 Hydrogen: high-purity hydrogen (for example, hydrocarbon-free), used as FID combustion gas. Warning: hydrogen under high pressure is a very flammable gas.
• 7.3 Air: high-purity (for example, hydrocarbon-free) compressed air, used as combustion-supporting gas for FID. Warning: supports combustion under high pressure.
• 7.4 Carbon disulfide (CS2): purity 99%, used as a solvent to reduce viscosity. It mixes easily with oils containing asphaltenes and has a small response on FID. Before selecting it as the sample diluent for this method, its hydrocarbon content should be determined. Warning: carbon disulfide is very flammable and toxic.
• 7.5 Cyclohexane: purity greater than 99%, used as a solvent to reduce viscosity. It mixes easily with oils containing asphaltenes but has a large response on FID. Before selecting it as the sample diluent for this method, its hydrocarbon content should be determined. Warning: cyclohexane is flammable.
• 7.6 Calibration mixture: a mixture of n-alkanes dissolved in a suitable solvent (conventionally n-C8 to n-C100). The final concentration is about 1 parts n-alkanes mixed into 100 parts solvent. According to the scope specified in this method (see 1.1), the mixture is required to have at least one compound whose boiling point is lower than the initial boiling point of the sample to be tested. The calibration mixture contains at least 11 known n-alkanes (for example, n-C8, n-C9, n-C10, n-C12, n-C16, n-C20, n-C30, n-C40, n-C50, n-C52 and n-C60). The boiling points of n-alkanes are listed in Table 1. Note: A suitable calibration mixture can be obtained by dissolving synthetic wax in a volatile solvent (for example, carbon disulfide or cyclohexane). Prepare a solution of 1 parts synthetic wax to 200 parts solvent. Lower-boiling n-alkanes should be added to ensure consistency with clause 7.5.
• 7.7 Response linearity mixture: prepare a mixture of about 10 individually quantitatively weighed alkanes (purity greater than 99%) that can cover the boiling range of this method. The component with the highest boiling point should be at least n-C40. The mixture should contain n-C40. Use a suitable solvent to prepare a solution with a mass fraction of each component from 0.5% to 2.0%.
• Table 1 Boiling points of n-alkanes: the source lists carbon numbers 2~100 corresponding to boiling points (℃), the source-text extraction table has misalignment and noise, specific values require confirmation against the source standard (source-text extraction).

5. Instruments and equipment

• 6.1 Gas chromatograph:
  • 6.1.1 Column oven: a gas chromatographic system capable of performing linear programmed temperature operation from ambient temperature (for example, to 50 ℃) to within the range of 400 ℃.
  • 6.1.2 Column programmed temperature: the chromatograph should be capable of linear programmed temperature operation up to 400 ℃ at an optional linear rate up to 20 ℃/min. The programmed temperature rate should be sufficiently reproducible so that each component in the calibration mixture described in clause 7.6 obtains a retention time repeatability of 0.1 min (6 s).
  • 6.1.3 Detector: a hydrogen flame ionization detector (FID) is required. The detector should meet or exceed the following indicators.
    • 6.1.3.1 Operating temperature can be as high as 400 ℃.
    • 6.1.3.2 Sensitivity: >0.005 C (unit requires confirmation against the source standard (source-text extraction))
    • 6.1.3.3 Minimum detectability: 1 (value requires confirmation against the source standard (source-text extraction))
    • 6.1.3.4 Linear range: not provided in the available source
    • 6.1.3.5 The connection between the column and the detector should be made while the column is being heated.
  • 6.1.4 Injection system: any injection system with the performance parameters in clause 6 may be used. Programmed temperature vaporization (PTV) and on-column injection systems have been used successfully.
• 6.2 Microsyringe: for on-column injection devices, use a microsyringe with a stainless steel needle of size 23 or smaller. Syringes with capacities of 0.1 μL~10 μL have been used.
  • 6.2.1 It is recommended to use an autosampler to obtain the best precision.
• 6.3 Chromatographic column: this method specifies the use of a highly thermally stable non-polar wall-coated open-tubular column (WCOT). Glass, quartz, and stainless steel columns with a diameter of 0.53 mm have been used successfully, and columns with cross-linked or bonded methyl silicone stationary phase with a liquid film thickness of 0.10 μm~1.0 μm have been used. The selection of column length and liquid film thickness is based on the premise of ensuring that at least C100 n-alkane (boiling point 615 ℃) can elute from the column. A chromatographic column and conditions should be used that separate the hydrocarbons in the oil product in order of increasing boiling point and meet the column resolution requirement of 8.2.1.
• 6.4 Flow/pressure control: the chromatographic column and gas chromatographic system should use the optimal carrier gas flow rate. It is recommended that the system be equipped with a constant-pressure/constant-flow device capable of maintaining a constant carrier gas flow rate throughout the temperature program.
• 6.5 Data acquisition system: composed of a recorder or equivalent equipment meeting the following requirements.
  • 6.5.1 Recorder: a potentiometric recorder with a range of 0 mV~1 mV or equivalent equipment, with a full-scale response time of 2 s or shorter, capable of graphical display.
  • 6.5.2 Integrator: A device capable of determining the cumulative area under chromatographic peaks. This device may be an electronic integrator/workstation based on a chromatographic data system. The integrator/workstation system shall have conventional chromatographic software for determining retention times and chromatographic peak areas (peak detection mode). In addition, the system shall be capable of converting the continuous integration signal from the detector into area slices at fixed intervals (area slice mode). These area slices for the entire collected analysis are then stored. The voltage range of the integrator/workstation (e.g., 1 V, 10 V) shall cover the linear range of the detector/potentiometer system. The operating software installed on the gas chromatograph allows the data mode of the baseline plot to be stored in memory. In subsequent sample runs, the baseline is automatically subtracted from the detection signal to correct for baseline drift. This integration system can also store and automatically subtract blanks from subsequent determinations.

6. Recommended Operating Conditions

• 8.1.1 Place the gas chromatograph and auxiliary equipment according to the manufacturer's instructions. Recommended operating conditions are given in Table 2.
• Table 2 Typical Chromatographic Operating Conditions:
  • Injector: Condition 1 cold on-column; Condition 2 cold on-column
  • Injector temperature: oven temperature tracking mode; oven temperature tracking mode
  • Autosampler: required for obtaining optimum precision; required for obtaining optimum precision
  • Data acquisition: acquire data in area slice mode (average data acquisition rate of 3 slices per second); acquire data in area slice mode (average data acquisition rate of 3 slices per second)
  • Column: capillary column 5 m × 0.53 mm, film thickness 0.15 μm (polymethylsilicone); capillary column 5 m × 0.53 mm, film thickness 0.15 μm (polymethylsilicone)
  • Flow control: UHP helium 12 mL/min (constant flow mode) or optimum column flow (helium makeup 18 mL/min); nitrogen 5 mL/min (constant flow mode) (nitrogen makeup 25 mL/min)
  • Detector: flame ionization detector, temperature 390 ℃; flame ionization detector, temperature 390 ℃
  • Oven temperature program: initial temperature 50 ℃, initial time 0 min, program rate 10 ℃/min, final temperature 380 ℃, final time 12 min, equilibration time 2 min; initial temperature 50 ℃, initial time 0 min, program rate 10 ℃/min, final temperature 380 ℃, final time 12 min, equilibration time 2 min
  • Injection volume: 1 μL; 1 μL
  • Sample dilution: diluted with carbon disulfide to 2% (mass fraction); diluted with carbon disulfide to 2% (mass fraction)
  • Calibration mixture dilution: diluted with carbon disulfide to 1% (mass fraction); diluted with carbon disulfide to 1% (mass fraction)
• 8.2 System performance requirements:
  • 8.2.1 Column resolution: Column resolution affects the determination of the entire boiling range distribution, and resolution is affected by the physical parameters of the column and operating conditions. Determine the column resolution using equation (1) and the n-C50 and n-C52 alkanes in the calibration mixture (see 7.6). Use the same conditions for sample analysis; the resolution (R) shall be at least 1.
    • R = [2(t2 - t1)] / [1.699(w1 + w2)] (1)
    • Where: R— resolution; t1— retention time of n-pentacontane, s; t2— retention time of n-dopentacontane, s; w1— half-peak width of n-pentacontane, s; w2— half-peak width of n-dopentacontane, s.
  • 8.2.2 Detector response calibration: This method assumes that the response of petroleum product hydrocarbons on FID is proportional to the mass of the individual compounds. Verification shall be performed when the system is placed in service and whenever the system or operating parameters change. Determine the linear response mixture (see 7.7) using the same operating procedure as for sample analysis (see Chapter 9). Calculate the relative response factor for each n-alkane (relative to n-tetracontane) according to equation (2).
    • Fn = (Mn / An) / (M40 / A40) (2)
    • Where: Fn— relative response factor; Mn— mass of the n-alkane in the mixture, g; An— peak area of the n-alkane in the mixture; M40— mass of n-tetracontane in the mixture, g; A40— peak area of n-tetracontane in the mixture.
    • The Fn of each n-alkane shall remain constant (the original text is truncated at source-text extraction here; the specific criterion requires confirmation against the source standard (source-text extraction)).
  • 8.2.3 Column temperature: The column temperature selected shall be such that the n-alkane with the highest boiling point (615 ℃) can elute from the chromatographic column before reaching the final temperature. The influence of other operating variables such as column diameter and sample amount. The temperature program rate actually used will be affected by other operating variables such as column diameter and sample amount.
  • 8.2.4 The column stationary phase is nonpolar, such as 100% polymethylsilicone.

7. Sampling and Sample Preparation

• 9.5 Sample preparation: Prepare the sample as a solution in a suitable solvent (e.g., carbon disulfide or cyclohexane) and then introduce it into the gas chromatograph.
  • 9.5.1 Place 0.1 g~1 g of sample into a screw-cap or crimp vial.
  • 9.5.2 Dilute the sample with solvent to 2% (mass fraction).
  • 9.5.3 Cap the vial and mix the mixture thoroughly and uniformly.
• 9.6.1 Carefully select an injection volume that does not exceed the linear range of the detector. Typical injection volumes range from 0.2 μL~2.0 μL of the diluted sample. The maximum sample signal shall not exceed the maximum calibration signal in 9.4.1.

8. Analysis Procedure

• 9.1 Analysis sequence: In order to obtain maximum reproducibility in these determinations, define and use a sequence table set according to the analytical method, which includes: injection and initial injector temperature (initial temperature), the time for the column temperature to reach the initial temperature and equilibrate (equilibration time), sample injection and system start, final temperature and final temperature hold time, etc. For details, see the typical chromatographic operating conditions listed in Table 2.
  • 9.1.1 After the chromatographic conditions meet the specified requirements, program the column temperature to the maximum usable temperature and hold at this temperature for the selected time, and according to the set analysis sequence, cool the column to the starting temperature.
  • 9.1.2 At the initial temperature and equilibration time, prepare the integrator/workstation; if retention time calibration is to be performed, use peak detection mode. For baseline determination (with or without solvent injection), operate in area slice mode. If peak integration software is used, this calculation is not required. This test method requires a slice rate of 5.0 Hz (5 slices per second). Other slice rates may also be used if the time or width of each slice is limited to within 0.02% and 0.12% of the retention time of the calibration component (C100). In the determination of the boiling range distribution, if it is ensured that the cumulative (bunched) slice data made are within these limits, other slice rates may also be used for other reasons.
  • 9.1.3 At the time set by the sequence table, inject the calibration mixture, solvent, or sample into the chromatograph; or when injecting an empty sample (baseline blank injection), start the chromatographic cycle and data acquisition of the integrator/workstation. Repeat all analyses or calibrations according to the proposed analysis sequence.
  • 9.1.4 Complete separation of sample peaks is not expected, so do not change the set detection sensitivity during the analysis.
• 9.2 Baseline: Perform one blank analysis on the sample (baseline blank). The blank analysis may be no injection or injection of the same volume of solvent as used in the sample determination, relying on subsequent data processing functions for baseline/solvent compensation. A typical blank analysis is completed before sample determination. In order to provide information about instrument operation or residual sample remaining from the previous sample determination, a blank determination may also be performed between two sample determinations or at the end of a sample sequence.
• 9.3 Solvent blank run: Because not all substances contained in engine oil samples can completely elute from the chromatographic column, it is recommended that additive-free base oil samples and engine oil sample liquids be analyzed in the same batch. After the analysis of the same batch of engine oil samples is completed, a solvent blank shall be run. Note: If the gas chromatograph already provides automatic baseline correction (see 6.5.2), no further area slice correction is required. If the electronic offset of the chromatograph is added to the signal after baseline compensation, additional area slice correction is required to subtract the electronic offset. Refer to the instructions of the instrument used to check whether the electronic offset is added to the signal. If the algorithm used is unclear, further correction is required by examining the area slice data. Determine whether the electronic offset is added to the compensated signal by examining the area slices before any chromatographic peaks elute (called corrected area slices). If these corrected area slice values (representing the true baseline) deviate from zero, the average value of these corrected area slices is subtracted from each corrected area slice.
• 9.4 Retention time versus boiling point calibration: Retention time-boiling point calibration shall be completed before each batch of sample analysis. Inject an appropriate amount (0.2 μL~2.0 μL) of the calibration mixture (7.6 clause) into the chromatograph, use the analysis sequence settings, and obtain the conventional (peak detection) data record of the measured peak retention times and peak areas of each component. If a boiling point distribution range report is required, acquire a record of time area slices. Figure 1 is an example of a calibration analysis plot.
  • 9.4.1 The chromatographic peaks of the calibration mixture sample shall be checked for asymmetry (non-Gaussian peak shape). Asymmetric peak shape indicates that the sample is overloaded on the column, causing the peak apex to shift relative to a non-overloaded peak, thereby affecting the determination of retention time. Therefore, the calibration of boiling point temperature will be erroneous due to sample overload on the column; the amount of stationary liquid coated on the column determines the amount of sample that can be tolerated. After reducing the injection volume of the calibration mixture or further diluting the sample, re-analyze the calibration mixture sample to avoid chromatographic peak deformation.
  • 9.4.2 Based on the mixture analysis, establish a calibration table by recording the time (retention time) of each n-alkane and the boiling point temperature of each component in the mixture. Table 1 lists the boiling point temperatures of n-alkanes. An example of typical calibration data showing the retention time and boiling point of each n-alkane is given in Table 3.
  • Table 3 Typical calibration report: The original text lists the corresponding data of retention time/min and boiling point/℃; the source-text extraction table has misalignment and noise; the specific values require confirmation against the source standard (source-text extraction).
• 9.6 Sample analysis: using the sample sequence settings, inject the sample into the gas chromatograph. Collect a continuous area slice record of the entire analysis (area slice mode).

9. Qualitative and quantitative determination and calculation formulas

• 10.1 Tabulate the retention times of the obtained calibration standard (normal paraffin mixture) against their corresponding boiling points. Use linear regression and interpolation to calculate the retention times of 371 ℃ points.
  • 10.1.1 Descriptions of how to apply linear regression can be found in many mathematics textbooks. Scientific calculators and program software can also be used to complete the calculations.
• 10.2 Subtract the solvent blank (see 9.3) from the sample analysis (see 9.6). If automatic baseline subtraction is used (see 9.3 note), omit this step.
• 10.3 Determine the total sample area and the area up to the retention time of 371 ℃. The above determinations can be accomplished using the area slice summation or conventional peak integration functions of commercially available chromatographic data processing systems. For baseline determination of a complete finished lubricating oil sample, see Figure 2.
  • 10.3.1 If area slice summation is used, follow the calculation steps in determination methods SH/T 0558 to find the starting point and ending point of sample elution.
    • 10.3.1.1 The sum of the final area slices from the start of sample elution to the end of the run is the total sample area C.
    • 10.3.1.2 The sum of the area slices from the start of sample elution to the retention time corresponding to 371 ℃ found in clause 10.1 is the area of the sample up to 371 ℃, B.
  • 10.3.2 If peak integration software is used, set the integration parameters to determine the total sample area C.
    • 10.3.2.1 Set the integration parameters, use the horizontal baseline mode, and determine the total area from the start of sample elution to the retention time corresponding to 371 ℃ found in clause 10.1. This is the area of the sample up to 371 ℃, B.
• 10.4 Determine the volatility of the engine oil up to 371 ℃, calculated according to formula (3):
  • A = 100 × B / C (3)
  • Where: A— volatility of the sample up to 371 ℃, %; B— area of the sample up to 371 ℃; C— total area of the sample; 100— factor for converting the area ratio to %.
• 10.5 Report the volatility result of the engine oil sample up to 371 ℃ to the nearest 0.1%. Figure 3 shows a typical volatility calculation result and a chromatogram of a finished engine oil.

10. Precision

• 12.1 Precision (95% confidence level): The precision of this test method was determined by statistical testing of test results from cooperating laboratories for volatility between 1.8% and 19.8%. Typical precision values are shown in Table 4.
• Table 4 Typical precision values (unit: %): The original text lists repeatability and reproducibility values corresponding to volatility 2.0~19.0. The source-text extraction table has misalignment and noise; specific values require confirmation against the source standard (source-text extraction).
• Repeatability: The difference between two repeat results obtained by the same operator using the same instrument on the same sample shall not exceed: Repeatability = 0.1352 × 2.5 (the original formula source-text extraction is truncated, requires confirmation against the source standard (source-text extraction)); where 2.5 is the average of the two repeat test results (the original wording requires confirmation against the source standard (source-text extraction)).
• Reproducibility: The difference between two independent test results obtained by different operators in different laboratories using the same sample shall not exceed: Reproducibility = 0.6036 × (the original formula source-text extraction is truncated, requires confirmation against the source standard (source-text extraction)).
• 12.2 Bias: The volatility defined by this test method is from 371 ℃ (the original text here source-text extraction is truncated, requires confirmation against the source standard (source-text extraction)); engine oil (the original text here source-text extraction is truncated, requires confirmation against the source standard (source-text extraction)); therefore bias cannot be determined.

11. Report

• 10.5 Report the volatility result of the engine oil sample up to 371 ℃ to the nearest 0.1%.
• 11.1 Monitor the reliability of the test results of this method by determining one reference oil per batch of samples. The acceptance value of the reference material is determined through round-robin testing. The precision values estimated through round-robin testing yield the precision statistical results in Chapter 12 of this test method. Suitable reference materials can be obtained from standard material suppliers.
• Other reporting requirements: not provided in the available source.

12. Referenced documents

• SH/T 0059 Determination of evaporation loss of lubricating oils (Noack method)
• SH/T 0558 Determination of boiling range distribution of petroleum fractions (gas chromatography)
• SH/T 0695 Determination of volatility of engine oils (gas chromatography)
• DIN 51581 Noack volatility test method
• ASTM D6417-03 Determination of engine oil volatility by capillary gas chromatography (modified adoption)

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 Q&A reference