NB/SH/T 0606-2019 Determination of hydrocarbon types in middle distillates — Mass spectrometry

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

• Standard number: NB/SH/T 0606—2019
• Chinese title: Determination of hydrocarbon types in middle distillates — Mass spectrometry
• English title: Standard test method for determination of hydrocarbon types in middle distillates by mass spectrometry
• Replacement relationship: Replaces SH/T 0606—2005 "Determination of hydrocarbon types in middle distillates (mass spectrometry method)"
• Previous versions: SH/T 0606—1994, SH/T 0606—2005
• Adoption relationship: Modified adoption by redrafting method of ASTM D2425-17 "Determination of hydrocarbon types in middle distillates — Mass spectrometry"
• Publication/implementation: Published on 2019-06-04, implemented on 2019-10-01
• Custodian: National Technical Committee for Standardization of Petroleum Products and Lubricants, Subcommittee on Petroleum Fuels and Lubricants (SAC/TC 280/SC1)
• Drafting organization: Sinopec Research Institute of Petroleum Processing

2. Scope of application and non-applicability

• This standard specifies a method for determining hydrocarbon types in middle distillates by mass spectrometry.
• Applicable to middle distillates with a distillation range of 170 ℃~365 ℃ (recovery temperatures for volume fractions of 5%~95% as determined by GB/T 6536), including biodiesel blended fuels containing fatty acid methyl esters at a volume fraction not greater than 20%.
• Samples with an average carbon number of paraffins between C12 and C30 can be analyzed (original text is "CIr2 to Co", requires confirmation against the source standard (source-text extraction)).
• Eleven hydrocarbon types can be determined: paraffins, one-ring naphthenes, two-ring naphthenes, three-ring naphthenes, alkylbenzenes, indans and/or tetralins, CₙH₂ₙ₋₁₀ (indenes and/or bicyclic alkylbenzenes, etc.), naphthalenes, CₙH₂ₙ₋₁₄ (acenaphthenes and/or biphenyls, etc.), CₙH₂ₙ₋₁₆ (fluorenes, etc.) and tricyclic aromatics.
• Not applicable: no explicit "not applicable" clause is provided in the available source.
• Interferences: sulfur-containing and nitrogen-containing non-hydrocarbon compounds are not included in the matrix calculation of this standard; if the sulfur content mass fraction is greater than 0.25%, it will interfere with the spectral peaks used for hydrocarbon calculation; if the olefin content mass fraction is greater than 5.0%, it will affect the determination results of various saturated hydrocarbons.

3. Method principle

According to Annex A, the saturated hydrocarbon and aromatic hydrocarbon fractions obtained by separating a middle distillate (including biodiesel blended fuel) sample are respectively subjected to mass spectrometric determination. The concentrations of various hydrocarbon types are determined by summing characteristic mass fragments. The average carbon number of hydrocarbons is estimated from the mass spectral data, and calculation is performed based on correction data determined from the average carbon numbers of various hydrocarbon types. The results for each fraction are normalized according to the mass fractions obtained by separation, and the results are expressed as mass fractions.

4. Reagents and materials (purity / preparation)

• n-Hexane: analytical reagent (A.5.1)
• Dichloromethane: analytical reagent (A.5.2), Warning: toxic, harmful to humans if ingested or absorbed through the skin
• Ethanol: anhydrous, analytical reagent (A.5.3)
• n-Hexadecane: chromatographic grade (A.5.4)
• n-Triacontane: chromatographic grade (A.5.5)
• Methyl oleate: >99% (A.5.6)
• Internal standard solution: n-triacontane dissolved in n-hexane, concentration 0.001 g/mL~0.005 g/mL (A.5.7)
• Gas: hydrogen, nitrogen or helium, purity not less than 99.99% (A.5.8)
• Sample for determining fatty acid methyl ester correction factor: accurately weigh a certain mass of methyl oleate and n-hexadecane standard and mix (mass ratio about 1:1), add an appropriate amount of n-hexane to dissolve, so that the sample mass fraction is about 1% (A.5.9); any fatty acid methyl ester in the range C16~C20 may be used (purity >99%)
• Quality control sample (method 1): prepared or purchased from aromatic hydrocarbon fraction and saturated hydrocarbon fraction obtained by separation using the chromatographic method in Annex B (A.5.10)
• Quality control check sample (method 2): prepared from aromatic hydrocarbon fraction, saturated hydrocarbon fraction and pure biodiesel obtained by separation using the chromatographic method in Annex B (A.5.11)
• Middle distillate reference sample: middle distillate with known contents of saturated hydrocarbon and aromatic hydrocarbon fractions (A.5.12)
• Biodiesel blended fuel reference sample containing fatty acid methyl esters (A.5.13)
• n-Pentane: chemical reagent (B.4.1)
• Dichloromethane: chemical reagent (B.4.2)
• Fine-pore silica gel: 75 μm~150 μm (B.4.3)

5. Instruments and equipment

• Mass spectrometer: applicability shall be verified by the performance tests in the applicable standard (7.1)
• Sample introduction system: any sample introduction system that does not cause loss, contamination, or change in composition during introduction may be used; it shall be maintained at a temperature rising within the range 125 ℃~325 ℃ (7.2)
• Microsyringe: 5 μL or 10 μL (7.3)
• Solid-phase extraction column: 3 mL solid-phase extraction column containing 1.5 g stationary phase (A.4.1)
• Conical flask: 25 mL (A.4.2); 25 mL, 250 mL (B.3.2)
• Syringe: 2 mL, 0.25 mL (A.4.3)
• Pipette gun: 100 μL (A.4.4)
• Pipette: 1 mL (A.4.5)
• Gas chromatograph: shall include a vaporization chamber, temperature-controlled column oven, chromatographic column, flame ionization detector and chromatography workstation (A.4.6)
• Chromatographic column: quartz capillary chromatographic column, column length 30 m, internal diameter 0.25 mm, film thickness 0.25 μm, non-polar, such as 100% dimethylpolysiloxane or 5% phenyl-methylpolysiloxane (Table A.1)
• Chromatographic column (B.3.1): as shown in Figure B.1
• Graduated cylinder: 100 mL (B.3.3)
• Water bath (B.3.4)
• Analytical balance: accurate to 1 mg (B.3.5)

6. Recommended operating conditions

• Mass spectrometer calibration conditions (8.1):
  • Adjust the repeller of the ion source so that the n-hexadecane molecular ion peak m/e 226 is maximized (8.1.1)
  • Perform mass scanning from m/e 40~292 (8.1.2)
  • Ionization voltage 70 eV, ionization current 10 μA–70 μA (original text is "70eY, ionization current 101A–701A", requires confirmation against the source standard (source-text extraction))
  • Note: The correction coefficients are obtained under conditions where the ion source parameters are adjusted so that the ratio of Σ67/Σ71 of n-hexadecane is 0.26/1; collaborative studies indicate that the acceptable range of the Σ67/Σ71 ratio is between 0.20/1 and 0.30/1
• Gas chromatography conditions (Table A.1):
  • Vaporization chamber temperature: 300 ℃
  • Detector temperature: 350 ℃
  • Column oven: hold at 60 ℃ for 2 min, then raise to 300 ℃ at 40 ℃/min, and hold for 5 min
  • Carrier gas: helium or nitrogen
  • Column flow rate: 1.0 mL/min
  • Split ratio: 20:1
  • Detector: flame ionization detector
  • Injection volume: 0.5 μL
  • Note: The instrument parameters given in the table are optional parameter conditions; a chromatographic column with column length 15 m–30 m and internal diameter 0.15 mm–0.32 mm may be used, and an appropriate column temperature program may be selected, as long as it ensures complete separation of the solvent, sample and internal standard in the analyzed sample

7. Sampling and sample preparation

• Sampling: Unless otherwise specified, sampling shall be carried out in accordance with GB/T 4756. Samples shall be stored in sealed containers (A.6).
• Solid-phase extraction separation (method 1, A.8.1.1):
  • Take one solid-phase extraction column and wet the stationary phase with 0.5 mL n-hexane
  • Take about 100 μL of sample and drip it onto the upper frit in the solid-phase extraction column so that it is completely adsorbed
  • Place a 25 mL conical flask below the sample outlet at the lower end of the solid-phase extraction column, rinse the stationary phase with 2 mL n-hexane, and after the n-hexane has just completely entered the stationary phase, rinse the stationary phase with 0.5 mL of a mixed solution of dichloromethane and ethanol in a volume ratio of 5:1 to elute the adsorbed saturated hydrocarbon fraction, at an elution rate of about 2 mL/min, and collect the eluate of the saturated hydrocarbon fraction in this 25 mL conical flask. After the added 0.5 mL of the mixed solution of dichloromethane and ethanol in a volume ratio of 5:1 has just completely entered the stationary phase, replace with another 25 mL conical flask, then rinse the stationary phase with 2 mL of a mixed solution of dichloromethane and ethanol in a volume ratio of 5:1 to elute the adsorbed aromatic hydrocarbon fraction, at an elution rate of about 2 mL/min, and collect the eluate of the aromatic hydrocarbon fraction in this 25 mL conical flask
  • Use a pipette to accurately measure 1.0 mL of internal standard solution, add it respectively to the 25 mL conical flasks receiving the aromatic hydrocarbon fraction and the saturated hydrocarbon fraction, and shake well
• Solid-phase extraction separation (method 2, A.8.2.1):
  • Take one solid-phase extraction column and wet the stationary phase with 0.5 mL n-hexane
  • Take about 100 μL of sample and drip it onto the upper frit in the solid-phase extraction column so that it is completely adsorbed
  • Place the first 25 mL conical flask below the sample outlet of the solid-phase extraction column, rinse the stationary phase with 2 mL n-hexane, and after the n-hexane has just completely entered the stationary phase, rinse the stationary phase with a mixed solution of 0.5 mL dichloromethane and n-hexane in a volume ratio of 1:1 to elute the adsorbed saturated hydrocarbon fraction, at an elution rate of about 2 mL/min, and collect the saturated hydrocarbon fraction eluate in the first 25 mL conical flask. When the added mixed solution of 0.5 mL dichloromethane and n-hexane in a volume ratio of 1:1 has just completely entered the stationary phase, replace with the second 25 mL conical flask, rinse the stationary phase with a mixed solution of 2 mL dichloromethane and n-hexane in a volume ratio of 1:1, and after the mixed solution of 2 mL dichloromethane and n-hexane in a volume ratio of 1:1 has just completely entered the stationary phase, rinse the stationary phase with a mixed solution of 0.5 mL dichloromethane and ethanol in a volume ratio of 1:1 to elute the adsorbed aromatic hydrocarbon fraction, at an elution rate of about 2 mL/min, and collect the aromatic hydrocarbon fraction eluate in the second 25 mL conical flask. When the added mixed solution of 0.5 mL dichloromethane and ethanol in a volume ratio of 1:1 has just completely entered the stationary phase, replace with the third 25 mL conical flask, and finally elute the adsorbed fatty acid methyl ester fraction with a mixed solution of 6 mL dichloromethane and ethanol in a volume ratio of 1:1, at an elution rate of about 2 mL/min, and collect the fatty acid methyl ester fraction eluate in the third 25 mL conical flask
  • Accurately measure 1.0 mL of the internal standard solution with a pipette, and add it respectively to the three 25 mL conical flasks receiving the aromatic hydrocarbon fraction, saturated hydrocarbon fraction and fatty acid methyl ester fraction, and shake well
• Chromatographic method (Appendix B):
  • Activate the silica gel at a constant temperature of 150 ℃ for 5 h, and place it in a glass bottle with a stopper for later use (B.5.1)
  • Weigh about 2 g of the sample, to the nearest 1 mg (B.5.2)
  • Fix the adsorption column vertically, and plug the end of the column tightly with degreased cotton. Then add silica gel, and tap the silica gel tight up to the marked line, and add 30 mL n-pentane to wet the chromatographic column. After the wetting liquid has completely entered the adsorption layer, transfer the weighed sample into the chromatographic column. Rinse the 25 mL conical flask containing the sample three times continuously with 30 mL n-pentane, and add the rinse liquid to the chromatographic column. After the sample has completely entered the adsorption layer, successively add n-pentane 150 mL and dichloromethane 150 mL to respectively rinse out the saturated hydrocarbon and aromatic hydrocarbon fractions. Use a 250 mL conical flask below the chromatographic column to receive the rinse liquid. The rinse rate is 1 mL/min. Then evaporate the solvent from the n-pentane and dichloromethane rinse liquids received in the 250 mL conical flasks respectively on a water bath. Transfer the saturated hydrocarbons and aromatic hydrocarbons from which the solvent has been removed respectively to weighed 25 mL conical flasks and bring to constant weight, for 5 min one cycle, until the loss between two consecutive weighings is less than 20 mg. However, its yield should reach above 95% (B.5.3)

8. Analysis steps

• For middle distillate samples that do not contain a fatty acid methyl ester fraction, separate the sample into saturated hydrocarbon and aromatic hydrocarbon fractions according to method 1 in Appendix A and quantitatively determine the mass fraction of each fraction. For biodiesel blended fuel samples that contain a fatty acid methyl ester fraction, separate the sample into saturated hydrocarbon, aromatic hydrocarbon and fatty acid methyl ester fractions according to method 2 in Appendix A and quantitatively determine the mass fraction of each fraction. Subject the separated saturated hydrocarbon and aromatic hydrocarbon fractions respectively to mass spectrometric determination (10.1).
• Inject a sufficient amount of sample into the injection system with a microsyringe. Record the mass spectrum of m/e 40–292 using the instrument conditions described in 8.1.1–8.1.3 (10.2).
• Warning: hydrocarbon samples in this distillate range are flammable.
• Gas chromatographic analysis (A.8.1.2 / A.8.2.2):
  • Preparation of the gas chromatograph: before analyzing samples, the instrument needs to be run blank once according to the analysis steps to remove residual substances in the gas chromatograph (A.8.1.2.1)
  • Subject the eluates of the aromatic hydrocarbon fraction and saturated hydrocarbon fraction to which the internal standard has been added respectively to gas chromatographic analysis to obtain chromatograms, and calculate the mass fractions of the aromatic hydrocarbon fraction and saturated hydrocarbon fraction based on the peak areas of the aromatic hydrocarbon peaks and internal standard peaks in the aromatic hydrocarbon fraction chromatogram and the peak areas of the saturated hydrocarbon peaks and internal standard peaks in the saturated hydrocarbon fraction chromatogram obtained by integration with the chromatography workstation (A.8.1.2.2)
  • Method 2: subject the sample for determining the fatty acid methyl ester correction factor to gas chromatographic analysis, and calculate the fatty acid methyl ester correction factor B based on the peak areas of methyl oleate and n-hexadecane and the masses of methyl oleate and n-hexadecane weighed when preparing the sample (A.8.2.2.2); subject the solutions of the aromatic hydrocarbon fraction, saturated hydrocarbon fraction and fatty acid methyl ester fraction containing the internal standard respectively to gas chromatographic analysis to obtain chromatograms, and calculate the mass fractions of the aromatic hydrocarbon fraction, saturated hydrocarbon fraction and fatty acid methyl ester fraction of the sample based on the peak areas; calculate the volume fraction of the fatty acid methyl ester fraction in the sample based on the density of the sample (A.8.2.2.3)
  • Note: Check the integration status of the chromatograms by the chromatography workstation to confirm that all chromatographic peaks have been reasonably integrated (perpendicular drop integration); if unreasonable, the integration parameters may be changed or the manual integration function may be used for re-integration

9. Qualitative and quantitative and calculation formulas

• Definition of characteristic mass fragment sums (Chapter 3):
  • Σ71 (paraffins): total peak intensity of m/e 71 and 85
  • Σ67 (monocyclic naphthenes): total peak intensity of m/e 67, 68, 69, 81, 82, 83, 96 and 97
  • Σ123 (dicyclic naphthenes): total peak intensity of m/e 123, 124, 137, 138, 151, 152, 165, 166, 179, 180, 193, 194, 207, 208, 221, 222, 235, 236, 249 and 250
  • Σ149 (tricyclic naphthenes): total peak intensity of m/e 149, 150, 163, 164, 177, 178, 191, 192, 205, 206, 219, 220, 233, 234, 247 and 248
  • Σ91 (alkylbenzenes): total peak intensity of m/e 91, 92, 105, 106, 119, 120, 133, 134, 147, 148, 161, 162, 175 and 176
  • Σ103 (indans and/or tetralins): total peak intensity of m/e 103, 104, 117, 118, 131, 132, 145, 146, 159, 160, 173, 174, 187 and 188
  • Σ115 (indenes and/or CₙH₂ₙ₋₁₀): total peak intensity of m/e 115, 116, 129, 130, 143, 144, 157, 158, 171, 172, 185 and 186
  • Σ128 (naphthalene): peak intensity of m/e 128
  • Σ141 (naphthalenes): total peak intensity of m/e 141, 142, 155, 156, 169, 170, 183, 184, 197, 198, 211, 212, 225, 226, 239 and 240
  • Σ153 (acenaphthenes and/or CₙH₂ₙ₋₁₄): total peak intensity of m/e 153, 154, 167, 168, 181, 182, 195, 196, 209, 210, 223, 224, 237, 238, 251 and 252
  • Σ151 (fluorenes and/or CₙH₂ₙ₋₁₆): total peak intensity of m/e 151, 152, 165, 166, 179, 180, 193, 194, 207, 208, 221, 222, 235, 236, 249 and 250
  • Σ177 (tricyclic aromatic hydrocarbons): total peak intensity of m/e 177, 178, 191, 192, 205, 206, 219, 220, 233, 234, 247 and 248
  • Polycyclic aromatic hydrocarbons: sum of the contents of naphthalene, naphthalenes, acenaphthenes and/or CₙH₂ₙ₋₁₄, fluorenes and/or CₙH₂ₙ₋₁₆, and tricyclic aromatic hydrocarbons
  • Total aromatic hydrocarbons: sum of the contents of alkylbenzenes, indans and/or tetralins, indenes and/or CₙH₂ₙ₋₁₀, and polycyclic aromatic hydrocarbons
• Calculation of the aromatic hydrocarbon fraction (11.1):
  • Σ71 = 71 + 85 (Formula 1)
  • Σ67 = 67 + 68 + 69 + 81 + 82 + 83 + 96 + 97 (Formula 2)
  • Σ91 = Σ[(91 + 14N) + (92 + 14N)] (Equation 3)
  • Σ103 = Σ[(103 + 14N) + (104 + 14N)] (Equation 4)
  • Σ115 = Σ[(115 + 14N) + (116 + 14N)] (Equation 5)
  • Σ141 = Σ[(141 + 14N) + (142 + 14N)] (Equation 6)
  • Σ153 = Σ[(153 + 14N) + (154 + 14N)] (Equation 7)
  • Σ151 = Σ[(151 + 14N) + (152 + 14N)] (Equation 8)
  • Σ177 = Σ[(177 + 14N) + (178 + 14N)] (Equation 9)
• Calculation of alkylbenzene mole fraction (11.2, Equation 10): Kₙ = [Pₘ - Pₘ₋₁(Kᵢ)]/Kₛ
  • Kₙ: mole fraction of each alkylbenzene, n represents the carbon number of each molecular fragment
  • m: relative molecular mass of the calculated alkylbenzene
  • m-1: relative molecular mass minus 1
  • P: m, peak intensity of the m-1 peak
  • Kᵢ: isotope correction factor (see Table 1)
  • Kₛ: molar sensitivity of alkylbenzenes with n carbon numbers (see Table 1)
  • Note: This calculation step assumes that other hydrocarbons do not contribute to the molecular peak and the molecular ion minus 1 peak of alkylbenzenes. The choice of the lowest carbon number as 10 is based on the boiling point of C10 alkylbenzenes being lower than that of 204 ℃, and their concentrations being negligible
• Calculation of average carbon number of alkylbenzenes (11.3, Equation 11): A = (Σ nKₙ)/(Σ Kₙ), n=10~18
• Calculation of naphthalene mole fraction (11.4, Equation 12): Xₙ = [Pₘ - Pₘ₋₁(Lᵢ)]/Lₛ
  • Xₙ: mole fraction of each naphthalene, n represents the carbon number of each molecular fragment
  • m: relative molecular mass of the calculated naphthalenes
  • m-1: relative molecular mass minus 1
  • P: m, peak intensity of the m-1 peak
  • Lᵢ: isotope correction factor (see Table 1)
  • Lₛ: molar sensitivity of naphthalenes with n carbon numbers (see Table 1)
  • Note: This calculation step assumes that other hydrocarbons do not contribute to the molecular peak and the molecular ion minus 1 peak of naphthalenes. For naphthalene with a relative molecular mass of 128, only the intensity of a single multi-isotope peak m/e 128 is taken in the matrix calculation. The average carbon number of naphthalenes ranges from 11 (relative molecular mass 142) to 18 (relative molecular mass 240)
• Calculation of average carbon number of naphthalenes (11.5, Equation 13): B = (Σ nXₙ)/(Σ Xₙ), n=11~18
• Calculation of saturated hydrocarbon components (11.7):
  • Σ71 = 71 + 85 (Equation 14)
  • Σ67 = 67 + 68 + 69 + 81 + 82 + 83 + 96 + 97 (Equation 15)
  • Σ123 = Σ[(123 + 14N) + (124 + 14N)] (Equation 16)
  • Σ149 = Σ[(149 + 14N) + (150 + 14N)] (Equation 17)
  • Σ91 = Σ[(91 + 14N) + (92 + 14N)] (Equation 18)
• Report: Report the mass fraction of each hydrocarbon class, polycyclic aromatic hydrocarbons, and total aromatic hydrocarbons, with results accurate to 0.1% (11.9). For biodiesel blend fuel samples, report the mass fraction or volume fraction of fatty acid methyl esters according to A.10 in Annex A, with results accurate to 0.1% (11.10).
• Annex A calculation formulas:
  • Method 1 aromatic component mass fraction Xₐ (%) is calculated according to Equation (A.1)
  • Method 1 saturated hydrocarbon component mass fraction Xₛ (%) is calculated according to Equation (A.2)
  • Fatty acid methyl ester correction factor B is calculated according to Equation (A.3): B = (M₁ × Aₙ)/(M₂ × Aₘ) (original text is "M,/Ag", requires confirmation against the source standard (source-text extraction))
  • Method 2 aromatic component mass fraction Xₐ (%) is calculated according to Equation (A.4)
  • Method 2 saturated hydrocarbon component mass fraction Xₛ (%) is calculated according to Equation (A.5)
  • Method 2 fatty acid methyl ester component mass fraction Xբ (%) is calculated according to Equation (A.6)
  • Fatty acid methyl ester volume fraction Xₚ (%) is calculated according to Equation (A.7): Xₚ = (Xբ × d)/dₚ, where dₚ = 880.0 kg/m³ (density of fatty acid methyl esters at 20 ℃), d is the density of the sample at 20 ℃ (determined by method SH/T 0604)
• Annex B calculation formulas:
  • Aromatic mass fraction Xₐ (%) is calculated according to Equation (B.1): Xₐ = [mₐ/(mₐ+mₛ)] × 100
  • Saturated hydrocarbon mass fraction Xₛ (%) is calculated according to Equation (B.2): Xₛ = [mₛ/(mₐ+mₛ)] × 100
  • Where: mₐ is the mass of the received aromatic hydrocarbons (g); mₛ is the mass of the received saturated hydrocarbons (g)

10. Precision

• The precision was obtained from cooperative tests conducted in 7 laboratories on 28 samples (including 10 middle distillate samples without fatty acid methyl esters and 18 biodiesel blend fuel samples with a fatty acid methyl ester volume fraction of 0.5%~20%, with the aromatic mass fraction in the samples ranging from 5%~50%), using the separation method in Annex A. The cooperative test results were statistically analyzed and calculated according to method GB/T 6683. The reliability of test results is judged according to the following provisions (95% confidence level) (12.1).
• Repeatability: The difference between two results obtained by the same operator using the same instrument on the same sample for repeated determinations shall not exceed the repeatability value specified in Table 6 (12.1.1).
• Reproducibility: The difference between two results obtained by different operators in different laboratories using different instruments on the same sample shall not exceed the reproducibility value specified in Table 7 (12.1.2).
• Table 6 Method Precision (% (mass fraction)):
  • Paraffins: content 13~54, repeatability 0.8, reproducibility 3.4
  • One-ring naphthenes: content 7~24, repeatability 0.8, reproducibility 3.2
  • Two-ring naphthenes: content 7~15, repeatability 0.6, reproducibility 3.1
  • Three-ring naphthenes: content 2~5, repeatability 3, reproducibility 1.4 (requires confirmation against the source standard (source-text extraction), repeatability and reproducibility values are suspected to be misaligned)
  • Alkylbenzenes: content 2~11, repeatability 0.5, reproducibility 1.0
  • Indanes and/or tetralins: content 1~23, repeatability 0.5, reproducibility 0.9
  • CₙH₂ₙ₋₁₀: content 0~8, repeatability 0.3, reproducibility 1.3
  • Naphthalenes: content 0~8, repeatability 0.3, reproducibility 0.7
  • CₙH₂ₙ₋₁₄: content 0~3, repeatability 0.2, reproducibility 0.5
  • CₙH₂ₙ₋₁₆: content 0~3, repeatability 0.2, reproducibility 0.5
  • CₙH₂ₙ₋₁₈: content 0~1, repeatability 0.2, reproducibility 0.3
  • Polycyclic aromatic hydrocarbons: content 0.5~15, repeatability 0.2470.28 (requires confirmation against the source standard (source-text extraction)), reproducibility 0.54X0.41 (requires confirmation against the source standard (source-text extraction))
  • Total aromatic hydrocarbons: content 5~50, repeatability 0.24X0.45 (requires confirmation against the source standard (source-text extraction)), reproducibility 0.62X0.30 (requires confirmation against the source standard (source-text extraction))
  • Note: X is the average of two determination results, %
• Bias: Since there is no reference material for determining bias, the bias of this method cannot be determined (12.2).
• Appendix A Precision (A.10):
  • The precision of this method was obtained by collaborative testing in 7 laboratories on 10 middle distillate samples with aromatic hydrocarbon mass fraction ranging from 5% to 50% and 18 biodiesel blend fuel samples with fatty acid methyl ester volume fraction ranging from 0.5% to 20%. The reliability of test results shall be judged according to the following provisions (95% confidence level)
  • Repeatability: The difference between two results obtained by the same operator using the same instrument on the same sample for repeated determinations shall not exceed the repeatability value specified in Table A.3 (A.10.1.1)
  • Reproducibility: The difference between two single and independent results obtained by different operators in different laboratories using different instruments on the same sample shall not exceed the reproducibility value specified in Table A.2 and Table A.3 (A.10.1.2)
  • Bias: Since there is no reference material for determining bias, the bias of this method cannot be determined (A.10.2)
  • Table A.2 Repeatability and reproducibility of method 1 (% (mass fraction)):
    • Aromatic hydrocarbons: content 5 to 50, repeatability 0.2789X8.30 (requires confirmation against the source standard (source-text extraction)), reproducibility 0.3862X0.4303 (requires confirmation against the source standard (source-text extraction))
    • Saturated hydrocarbons: content 50 to 95, repeatability 374.95.X1308 (requires confirmation against the source standard (source-text extraction)), reproducibility 503.27X-1.3628 (requires confirmation against the source standard (source-text extraction))
    • Note: X is the average of two determination results, % (mass fraction)
  • Table A.3 Repeatability and reproducibility of method 2 (% (mass or volume fraction)):
    • Aromatic hydrocarbons: content 5 to 50, repeatability 0.3609X"323 (requires confirmation against the source standard (source-text extraction)), reproducibility 0.5836X0.3522 (requires confirmation against the source standard (source-text extraction))
    • Saturated hydrocarbons: content 30 to 95, repeatability 7.7236XD42N (requires confirmation against the source standard (source-text extraction)), reproducibility 11.551X-0.4231 (requires confirmation against the source standard (source-text extraction))
    • FAME: content 0.5 to 20, repeatability 0.1250X0.65:9 (requires confirmation against the source standard (source-text extraction)), reproducibility 0.1948X0.6549 (requires confirmation against the source standard (source-text extraction))
    • Note: X is the average of two determination results, % (mass fraction or volume fraction)

11. Report

• Report the mass fraction of each hydrocarbon class, polycyclic aromatic hydrocarbons, and total aromatic hydrocarbons, with results accurate to 0.1% (11.9).
• For biodiesel blend fuel samples, report the mass fraction or volume fraction of fatty acid methyl esters according to A.10 in Appendix A, with results accurate to 0.1% (11.10).
• Appendix A Report (A.11): For method 1, report the mass fractions of aromatic hydrocarbons and saturated hydrocarbons in the sample, with results taken to 0.1%. For method 2, report the mass fractions of aromatic hydrocarbons and saturated hydrocarbons and the mass fraction or volume fraction of fatty acid methyl esters in the sample, with results taken to 0.1%. And indicate the method used (method 1 or method 2).
• Appendix B Report (B.7): Report the mass fractions of aromatic hydrocarbons and saturated hydrocarbons in the sample, with results taken to 0.1%.

12. Normative References

• GB/T 4756 Manual sampling of petroleum liquids
• GB/T 6536 Determination of distillation characteristics of petroleum products at atmospheric pressure
• SH/T 0604 Determination of density of crude oil and petroleum products (U-shaped oscillating tube method)
• GB/T 6683 Determination of precision data for petroleum product test methods (reference document)
• ASTM D2425-17 (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 Reference Q&A