SH/T 0631-1996 Determination of barium, calcium, phosphorus, sulfur and zinc in lubricating oils and additives (X-ray fluorescence spectrometry)

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Card type: Test method

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

• Standard number: SH/T 0631-1996
• Chinese full title: Determination of barium, calcium, phosphorus, sulfur and zinc in lubricating oils and additives (X-ray fluorescence spectrometry)
• English name: not provided in the available source (the foreword mentions equivalent adoption of ASTM D4927-93, but does not give the English name of this standard)
• Replacement relationship: not provided in the available source (no mention of replacing any old standard)
• Adoption relationship: equivalent adoption of the B method (mathematical correction method) in ASTM D4927-93 "Determination of barium, calcium, phosphorus, sulfur and zinc in lubricating oils and additives (X--ray fluorescence spectrometry)"
• Main differences from the ASTM D4927-93 B method (foreword):
  1. Standard sample preparation: the ASTM D4927-93 B method recommends 20 samples, this standard recommends 32 samples, with component ratios spanning the entire measurement range.
  2. Reagents: the reagents recommended by the ASTM D4927-93 B method are difficult to purchase domestically; this standard instead selects relevant domestically readily available reagents as substitutes, achieving the same effect.
  3. Sample loading amount: the ASTM D4927 B method recommends "half cup"; this standard proposes loading "half cup" for downward-irradiation spectrometers and "full cup" for upward-irradiation spectrometers.
• Publication/implementation: published on 1996-05-24, implemented on 1996-12-01
• Issuing unit: China Petrochemical Corporation
• Drafting unit: Research Institute of Daqing Petrochemical General Plant, Sinopec
• Main drafters: Chen Suozhi, Li Jiandong, Ji Guifen

2. Scope of application and non-applicability

• Applicable to the determination of the content of barium, calcium, phosphorus, sulfur and zinc in lubricating oils and additives with an element concentration range of 0.03% (m/m) to 1.0% (m/m) [for sulfur, 0.01% (m/m) to 2.0% (m/m)].
• Lubricating oils and additives with high element concentrations can also be determined after dilution.
• Not applicable: no explicit non-applicability clause is provided in the available source.

3. Method principle

• Use a mathematical method to correct the measured intensity of the analysis element to prevent interference from other elements in the sample; using a mathematical method for correction requires knowing the X-ray fluorescence spectral intensity of all elements in the sample.
• Place the sample in the X-ray beam, measure the X-ray fluorescence intensity and background intensity of the analytical lines of barium, calcium, phosphorus, sulfur and zinc; the concentration of the analysis element is obtained by calculation from the measured net intensity (analytical line intensity minus background intensity) and the correction coefficients obtained from standard samples.
• Use a series of standard samples to obtain inter-element correction coefficients by regression analysis, and at the same time perform initial calibration of the X-ray fluorescence spectrometer.
• For subsequent instrument calibration, only a small number of samples are needed; this calibration is performed only when the inter-element correction coefficients need to be redetermined. When performing a large number of analyses, any one of these samples can be used to monitor instrument drift.
• When determining additives or composite additives, the sample may be diluted with a diluent (white oil, kerosene, xylene, etc.) so that the concentration of the analysis element is within the range described in Chapter 1.

4. Reagents and materials (purity / preparation)

4.1 Reagents (6.1)

• All reagents should use reagent-grade chemicals, with known contents of barium, calcium, phosphorus, sulfur and zinc. Reagents with purity of 97% (m/m) or above may be used without standardization; reagents with purity below 97% (m/m) may also be used after accurate standardization of the target elements in the relevant organic chemicals according to relevant standards.
• 6.1.1 Barium octoate (or barium naphthenate, barium alkylphenate)
• 6.1.2 Calcium octoate (or calcium naphthenate, calcium salicylate)
• 6.1.3 Di(2-ethylhexyl) phosphate (or di-n-butyl phosphite)
• 6.1.4 Di-n-butyl sulfide (or sulfurized isobutylene)
• 6.1.5 Zinc octoate (or zinc naphthenate)
• Adoption note 1] The reagents listed in parentheses are substitutes recommended by this standard for the reagents recommended by the ASTM D4927-93 B method.

4.2 Materials (6.2)

• 6.2.1 Helium: used in the optical path of the spectrometer.
• 6.2.2 P-10 ion gas: argon containing 90% (V/V) and 10% (V/V) methane, used for the flow proportional counter.
• 6.2.3 Dilution solvent: a suitable solvent that does not contain metals and phosphorus and has a sulfur content below 0.01% (m/m) (e.g., kerosene, white oil, trimethylbenzene, etc.).

5. Instruments and equipment

• 5.1 To achieve detection of soft 0.1nm to 1nm X rays, the X-ray fluorescence spectrometer should have the following configuration:
  • 5.1.1 X-ray tube: chromium, rhodium, scandium; other targets may also be used.
  • 5.1.2 Helium optical path.
  • 5.1.3 Replaceable crystals: germanium, lithium fluoride (LiF200), graphite, polyethylene terephthalate (PET), or combinations thereof; other crystals may also be used.
  • 5.1.4 Pulse height analyzer or other energy discriminator.
  • 5.1.5 Detector: flow proportional counter, scintillation counter, or a combination of both.
• 5.2 Plastic cup with thin-film window: suitable films include Mylar, polypropylene or polyimide film, with a thickness of 6.3 to 8.8 pm (requires confirmation against the source standard (source-text extraction): the unit is suspected to be μm).
  • Note: Some films contain substances that contaminate the analysis elements; the degree of contamination should be evaluated, and the same batch number of film should be used throughout the analysis.

6. Recommended operating conditions

• Table 2 Instrument operating conditions (Note: the operating conditions in Table 2 vary with different instruments and are for reference only):

• Detector description: S is a scintillation detector; F is a flow proportional detector; FS is both detectors.
• Counting time: the counting time for the analytical line at each wavelength position is at least 60s (see 8.2).

7. Sampling and sample preparation

• 7.1 Accurately dilute barium octoate, calcium octoate, di(2-ethylhexyl) phosphate, di-n-butyl sulfide and zinc octoate with dilution solvent to the concentrations listed in Table 1.
• Table 1 Reference concentrations of standard samples % (m/m) (standard sample numbers 1 to 5):

• Table 1 (continued) Standard sample numbers 7 to 32 (Note: the data row for standard sample number 6 is not found in Table 1 of the original text; requires confirmation against the source standard (source-text extraction)):

• Adoption note 2] Prepare with standard samples; the ASTM D4927-93 B method recommends 20 samples, while this standard recommends 32 samples.
• Note: Some cells in Table 1 have severe source-text extraction noise (e.g., “◎” and “0” are confused with blanks); the values in the above table are based on the original text layer, and doubtful points have been marked as requires confirmation against the source standard (source-text extraction).

8. Analysis Procedure

• 8.1 Fill each plastic cup pre-fitted with a thin-film window separately with the calibration standard solution; for a downward-irradiation spectrometer, fill half a cup; for an upward-irradiation spectrometer, fill a full cup, ensuring the film is flat.
• 8.2 Place the plastic cup in the X radiation beam, and under the conditions specified in Table 2, measure and record the net intensity of the analyte element in each standard sample (analyte line intensity minus background intensity). The counting time for the analyte line at each wavelength position shall be at least 60s.
• 8.3 The inter-element calibration coefficients and the slope and intercept of the calibration curve can be obtained by regression analysis using the program supplied with the instrument or a model similar to the following form.
• 8.4 When determining the slope, intercept, and inter-element correction coefficients, only one initial calibration is required; for subsequent recalibrations, only two standard samples are needed to check the slope and intercept. The two selected standard samples cover the concentration range expected for unknown samples. Alternatively, one (optional) stable standard sample may be prepared and measured periodically to detect instrument drift.
• 9.1 Load the sample according to the procedure in 8.1.
• 9.2 The net intensity of each element in all test samples can be obtained by the method for determining standard samples described in 8.2.
• 9.3 Using the measured intensities and the correction coefficients obtained as described in 8.3, calculate the concentration of the analyte element in each test sample.
• 9.4 When the concentration of barium, calcium, phosphorus, and zinc in the test sample exceeds 1% (m/m), or the concentration of sulfur exceeds 2% (m/m), the test sample shall be diluted and steps 9.1 to 9.3 shall be repeated.

9. Qualitative and Quantitative Calculation Formulas

• The concentration C_i % (m/m) of the analyte element i is calculated according to formula (1):

  C_i = (D_i + E_i I_i)(1 + Σ a_ij C_j)

  Where:

  • D_i — intercept of the calibration curve for element i;
  • E_i — slope of the calibration curve for element i;
  • I_i — net intensity of element i;
  • a_ij — inter-element correction coefficient of interfering element j on analyte element i;
  • C_j — concentration % (m/m) of interfering element j.

• Using formula (1), the slope, intercept, and a series of inter-element correction coefficients for each analyte element can be calculated.

• Note: In the original formula, the subscripts and the summation symbol source-text extraction have considerable noise; the above formula has been organized according to the original semantics, and symbol details require confirmation against the source standard (source-text extraction).

10. Precision

• 10.1 The reliability of test results shall be judged using the following provisions (95% confidence level).
  • 10.1.1 Repeatability — the difference between two successive test results obtained by the same operator, using the same instrument, under constant operating conditions, and with normal and correct operation according to the test method on the same test material shall not exceed the value listed in Table 3.
  • 10.1.2 Reproducibility — the difference between two single and independent results obtained by different operators working in different laboratories, with normal and correct operation according to the test method, on the same test material shall not exceed the value listed in Table 3.
• Table 3 Precision % (m/m) (Note: X represents the average value of the measured analyte element concentration):

• Table 3 also contains several values (0.001, 0.003, 0.004, 0.006, 0.016, 0.016, 0.018, 0.019, 0.002, 0.012, 0.050 9 (X+0.0214), 0.019 3X, etc.) that, due to source-text extraction serialization, cannot be reliably matched to specific element rows; requires confirmation against the source standard (source-text extraction).
• 10.2 Bias — because there is no suitable reference material with known composition, the bias of this standard method has not been determined.

11. Report

not provided in the available source.

12. Referenced Documents

• ASTM D4927-93 “Determination of Barium, Calcium, Phosphorus, Sulfur, and Zinc in Lubricating Oils and Additives (X- X-ray Fluorescence Spectrometry)” (equivalent to adopting its B method)
• Other referenced documents: not provided in the available source.

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