NB/SH/T 0824-2010 Determination of additive element content in lubricating oils — Inductively coupled plasma atomic emission spectrometry

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Card type: Test method

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

• Standard number: NB/SH/T 0824—2010
• Chinese title: Determination of additive element content in lubricating oils — Inductively coupled plasma atomic emission spectrometry
• English title: Standard test method for determination of additive elements in lubricating oils by inductively coupled plasma atomic emission spectrometry
• Replacement relationship: not provided in the available source (the foreword only states modified adoption of ASTM D4951-06, and does not mention replacing an old standard number)
• Adoption relationship: modified adoption of ASTM D4951-06 "Standard Test Method for Determination of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectrometry", redrafted according to ASTM D4951-06
• Main technical differences from ASTM D4951-06: some referenced standards were changed to the corresponding Chinese national standards and industry standards; the wording of repeatability and reproducibility was modified according to Chinese practice
• Issued / implemented: issued by 2010-05-01, implemented by 2010-10-01
• Issuing authority: National Energy Administration
• Proposing authority: China Petrochemical Corporation
• Technical committee: Sinopec Research Institute of Petroleum Processing
• Drafting organization: Sinopec Lubricant Research and Development (Shanghai) Center
• Participating drafting organization: Sinopec Lubricant Shanghai Branch
• Main drafters: Lü Wenji, Zhang Ruili, Hu Pengcheng, Lu Meiyu, Chen Ying
• Appendices: Appendix A and Appendix B are both informative appendices

2. Scope of application and non-applicability

• 1.1 is applicable to the determination of barium, boron, calcium, copper, magnesium, molybdenum, phosphorus, sulfur and zinc contents in unused lubricating oils and additive packages.
• 1.2 precision is applicable to samples diluted in solvent at a mass ratio of 1%~5%.
• The concentration ranges given in the 1.3 precision table are the sample concentration ranges of the interlaboratory study; this standard is also applicable to samples with concentrations above and below the concentration ranges given in the precision table. The lower limit of determinable concentration depends on instrument sensitivity and sample dilution factor, and the upper limit depends on the highest concentration of the calibration curve and the sample dilution factor.
• 1.4 instruments capable of operating at wavelength 180 nm can determine sulfur content.
• 1.5 uses [SI] International System of Units units.
• 1.6 The standard involves certain hazardous materials, operations and equipment, but does not address all safety issues associated with them; users must establish appropriate safety and protective measures before use and determine corresponding management systems.
• Non-applicability: no explicit "non-applicability" clause is provided in the available source.

3. Method principle

Weigh a portion of test sample and dilute it in mixed xylene or another solvent at a certain mass ratio. If necessary, weigh the internal standard directly into the sample solution or pre-mix the internal standard with the dilution solvent. Prepare calibration standards in the same manner. Introduce the sample solution into an inductively coupled plasma atomic emission spectrometer (ICP-AES) by free aspiration or peristaltic pump for measurement, and calculate the concentration of the element being determined in the sample solution by comparing the emission intensities of the element in the test sample and the standard solutions (the source text here has source-text extraction as "degree", suspected to be "concentration", requires confirmation against the source standard (source-text extraction)).

4. Reagents and materials (purity / preparation)

• 7.1 Reagent purity: all reagents used in the test are of analytical grade. If reagents of other grades are used, their purity must be proven sufficiently high that use will not reduce detection accuracy (the source text has source-text extraction as "detection accurate", requires confirmation against the source standard (source-text extraction)).
• 7.2 Base oil: white oil whose viscosity at room temperature is as close as possible to that of the sample being analyzed, or a lubricating oil base oil that does not contain the elements being determined. Note: lubricating oils contain sulfur; when determining sulfur content, it is recommended to use sulfur-free white oil to prepare standards and additive package samples.
• 7.3 Internal standard (as needed): an oil-soluble internal standard element is required; the following oil-soluble internal standards have been successfully used in interlaboratory precision verification tests: Ag, Be, Cd, Co (most common), Mn, Pb, Y (the source text has source-text extraction as "Co (most common PwJa", requires confirmation against the source standard (source-text extraction)).
• 7.4 Organic standard substances: multi-element standard substances may be prepared from single-element standard substances according to the preparation method of ASTM D4307, with each element concentration at about 0.1% (mass fraction); when preparing multi-element mixed standard substances, ensure mixing uniformity. It is recommended to use commercial multi-element mixed standard substances with each element concentration at 0.1% (mass fraction).
  • 7.4.1 To cover all elements, consideration may be given to using multiple multi-element standards, which facilitates selection of multi-element standard concentrations and element combinations, and also facilitates selection of typical concentrations for unused lubricating oils. Rules that must be observed: the emission intensity of the selected working standard concentrations must be accurately measurable (that is, the emission intensity must be significantly greater than the background), and the calibration curve measured with these standards should be in the linear region. Instrument manufacturers (the source text has source-text extraction as "[garbled preceding text]. instrument manufacturer [name garbled]", requires confirmation against the source standard (source-text extraction)) will print the linear detection range in the operation manual.
  • 7.4.2 Some commercially available organometallic standards are made from metal sulfonates and therefore contain sulfur; when determining sulfur, a separate sulfur standard needs to be prepared, or it may be prepared by mixing NIST SRM 1622 (the source text has source-text extraction as "NISTYSRMI622", requires confirmation against the source standard (source-text extraction)).
  • 7.4.3 If the sulfur content has been determined by a suitable method (such as SH/T 0631), metal sulfonates may be used as sulfur standards (the source text at source-text extraction is severely noisy; this item is inferred and organized, requires confirmation against the source standard (source-text extraction)).
  • 7.4.4 Petroleum additives may also be used as organometallic standards if they neither affect determination precision nor introduce determination bias.
• 7.5 Diluents: mixed xylene, o-xylene and kerosene have all been used in interlaboratory precision tests.

5. Instruments and equipment

• 6.1 Inductively coupled plasma atomic emission spectrometer (ICP-AES): an atomic emission spectrometer equipped with a quartz ICP torch and radio frequency generator capable of forming and maintaining plasma, either sequential or simultaneous type.
• 6.2 Analytical balance: readability 0.001 g or 0.0001 g, maximum load 150 g.
• 6.3 Peristaltic pump (recommended): use of a peristaltic pump is especially recommended to ensure stable solution introduction flow rate. Pump speed range 0.5 mL/min~3 mL/min (the source text has source-text extraction as "3[unreadable characters]mn", requires confirmation against the source standard (source-text extraction)). The pump tubing must withstand contact with organic solvent (diluent) for at least 6 h (the source text has source-text extraction as "6I", requires confirmation against the source standard (source-text extraction)); fluororubber tubing is recommended (the source text has source-text extraction as "[uncertain prefix]rubber tubing", requires confirmation against the source standard (source-text extraction)).
• 6.4 Solvent dispenser (optional): a calibrated solvent dispenser capable of accurately adding the required mass of solvent. Ensure that the minimum drop amount of solvent does not affect accuracy (the source text has source-text extraction as "[garbled wording about minimum solvent amount and accuracy]", requires confirmation against the source standard (source-text extraction)).
• 6.5 Sample receiving container: a glass or polyolefin bottle of appropriate size with an inner cap (the source text has source-text extraction as "sample collection container [garbled name]: suitably sized glass or polyolefin bottle with inner cap [garbled wording]", requires confirmation against the source standard (source-text extraction)).
• 6.6 Vortex mixer (optional): used to stir the sample with added diluent so that the sample dissolves completely.
• 6.7 Ultrasonic homogenizer (optional): a water bath type or probe type ultrasonic homogenizer may be used to homogenize the sample solution.

6. Recommended operating conditions

• 10.1 Instrument conditions: because of differences in the design of various instruments and inductively coupled plasma (ICP) excitation sources and differences in the analytical wavelengths selected by various spectrometers, detailed instrument operating conditions cannot be given. Please refer to the operating conditions for organic solvent introduction in the instrument operation manual and set the instrument operating conditions according to the selected diluent.
• 10.2 Peristaltic pump: if a peristaltic pump is used, inspect the pump sample introduction tubing before start-up each day and replace it if necessary. Check the solution uptake rate and adjust it to the required sample introduction rate.
• 10.3 ICP Excitation source
  • 10.3.1 Sample analysis may be carried out only after the plasma has been ignited for at least 30 min; during the warm-up period, nebulize the dilution solvent and check whether carbon deposits form after the torch is ignited; once carbon deposits occur, immediately replace the torch and take appropriate measures with reference to the instrument operation manual. Note 2: using argon (the source text has source-text extraction as "[garbled gas name]", requires confirmation against the source standard (source-text extraction)) containing oxygen at 1% (volume fraction) as the nebulizer gas can eliminate carbon deposits accumulated at the nozzle port of the torch.
  • 10.3.2 Generally, increasing the intermediate argon flow or lowering the position of the flame torch relative to the load coil, or both, can reduce torch carbon deposition. Note 3: some instrument manufacturers recommend a longer warm-up time to reduce changes in the slope of the calibration curve.
• 10.4 Spectral line profile: perform spectral line profile scanning according to normal instrument operation.
• 10.5 Operating parameters: set appropriate instrument operating parameters in this method document so that they are suitable for determination of the elements to be measured. These parameters include: element, wavelength, background correction (optional), correction factor (see clause 5.1), integration time and internal standard correction (as needed); each measurement requires multiple integrations (generally 3 times), and the typical integration time is 10 s.
• Table 1 Elements to be determined and suggested wavelengths (unit: nm):
  • Barium: 233.53, 455.40, 493.41
  • Boron: 182.59, 249.68
  • Calcium: 315.88, 317.93, 304.4 (the source text has source-text extraction as "304.4. H22. 67", requires confirmation against the source standard (source-text extraction))
  • Copper: 324.75
  • Magnesium: 279.08, 279.55, 285.21
  • Molybdenum: 202.03, 281.62
  • Phosphorus: 177.51, 178.29, 213.62, 214.91, 253.40 (the source text has source-text extraction as "177.51,178.-29. 213.62, -214,91,253.40", requires confirmation against the source standard (source-text extraction))
  • Sulfur: 180.73, 182.04, 182.62
  • Zinc: 202.55, 206.20, 213.86, 334.58, 481.05
  • Note: these wavelengths are only suggested choices and do not mean that all must be selected. Determination of boron, phosphorus and sulfur at wavelengths below 190 nm requires a vacuum optical chamber or purging of the optical path with inert gas (the source text has source-text extraction as "purge the optical path with [incomplete gas name]", requires confirmation against the source standard (source-text extraction)).

7. Sampling and Sample Preparation

• 9.1 The purpose of sampling is to obtain a representative test sample. Therefore, the sampling technique will affect the measurement precision of this method. Sampling shall be carried out in accordance with the provisions of GB/T 4756.
• 11.1 Diluent: refers to the dilution solvent containing the internal standard (see clause 8.2).
• 11.2 The preparation of the sample solution is the same as the preparation of the calibration standard (see clause 12.2); the mass percentage of diluent in the calibration standard and the sample solution must be equal.
  • 11.2.1 Lubricating oil sample: weigh an appropriate amount of sample (accurate to 0.001 g); the weighed amount is determined according to the metal content in the sample; dilute with diluent on a mass percentage basis and mix uniformly.
  • 11.2.2 Composite additive sample: the elemental concentration values in composite additives are usually ten times those in lubricating oil; therefore, before adding diluent, first mix the composite additive with base oil.
    • 11.2.2.1 Weigh an appropriate amount of composite additive (accurate to 0.001 g); the weighed amount can be determined according to the metal content in the sample; add approximately ten times the amount of base oil (accurate to 0.001 g); dilute this mixture with diluent and mix uniformly.
• 11.3 Record all masses; divide the sample mass by the sum of the masses of diluent, sample, and base oil (if any) to obtain the dilution factor.

8. Analytical Procedure

• 14.1 Determine the sample solution in the same manner as the conditions for establishing the calibration curve (i.e., the same integration time, background correction points (optional), and plasma conditions, etc.). Between two sample solution measurements, pre-spray the diluent for at least 60 s.
• 14.2 When the concentration of the analyte element exceeds the linear range of the calibration curve, re-mix the sample with base oil and then dilute with diluent (see 11.2.2.1), and re-analyze the sample solution.
• 14.3 After every 15 samples analyzed, test a check standard once. If the obtained result exceeds the confirmed value ±5% (relative value), in order to ensure the accuracy of the results, it is necessary to recalibrate the instrument and re-analyze the samples after the previous check.
• Internal standard calibration (8):
  • 8.1 It shall be ensured that the same concentration (or a known concentration) of the internal standard element is added to each solution to be measured (sample solution or standard solution), and that this element is not present in the original solution. Usually, the internal standard element is added to the dilution solvent. Internal standard compensation can use the following two different methods:
    • 8.1.1 By measuring the ratio of the spectral line intensity of each analyte element to the internal standard intensity per unit concentration, a ratio calibration curve is established; the concentration of each analyte element in the sample solution can be read directly from the calibration curve.
    • 8.1.2 After dissolving the organometallic compound used as the internal standard in the diluent, transfer it to a solvent dispenser. The stability of the solution shall be monitored. When there is a significant change in the internal standard element, it shall be re-prepared (usually once a week). The concentration of the internal standard element shall be at least 100 times its detection limit; the typical concentration range is between 10 mg/kg~20 mg/kg.
  • Note 1: This test method specifies that the internal standard be added to the dilution solvent because this technique is common and effective in sample preparation. As long as the internal standard concentration is constant or its exact value is known, it may also be added separately during sample preparation.
• Calibration (13):
  • 13.1 When the instrument is in use, the linear range of all calibration curves must be examined. The linear range is examined by measuring standards with concentrations between the blank and the calibration standard and standards with concentrations higher than the calibration standard. Sample analysis must fall within the linear range of the calibration curve.
  • 13.2 Before starting the testing of each group of sample solutions, establish a two-point calibration curve using the blank and the calibration standard.
  • 13.3 Determine each element in the check standard on the calibration curve. If the difference between the test result and the confirmed value of the check standard does not exceed ±5% (relative value), analysis testing may proceed; otherwise, it is necessary to adjust the instrument and re-establish the calibration curve.
  • 13.4 Different calibration curves can be established according to the internal standard compensation method.
    • 13.4.1 When the calibration curve is established using the ratio of the emission intensity of the analyte element to the emission intensity of the internal standard element versus the concentration of the analyte element, the expression for the relative intensity I(Re) of the analyte element is given in formula (1): I(Re) = (I(e) − I(Be)) / I(is) …(1); where: I(Re)— relative intensity of analyte element e; I(e)— intensity of element e; I(Be)— blank intensity of element e; I(is)— intensity of the internal standard element.
    • 13.4.2 When internal standard compensation is performed by multiplying the ratio of the actual concentration of the internal standard to its measured concentration by the test result of a certain sample, the calibration curve is in fact the relationship curve of [I(e) − I(Be)] versus the concentration of the analyte element.
• Preparation of calibration standards and check standards (12):
  • 12.1 Diluent: refers to the dilution solvent containing the internal standard (see clause 8.2).
  • 12.2 This method allows the dilution factor to be selected, i.e., the relative amounts of sample and diluent. However, throughout the entire test process, the mass percentage of the standard and sample in the diluent must remain consistent and must be between 1%~5% (mass fraction).
    • 12.2.1 The type of dilution solvent, the preparation of the internal standard-containing diluent, and the dilution factor are chosen by the user of this standard.
  • 12.3 Blank: prepare the blank by diluting base oil or white oil with diluent.
  • 12.4 Calibration standard: weigh 1 g~3 g (accurate to 0.001 g) of each multi-element standard into the corresponding sample solution container, and dilute with diluent on a mass percentage basis.
  • 12.5 Check standard: prepare the check standard required for instrument checking by the method used to prepare the calibration standard, with a concentration close to that of the sample solution. It is preferable to use organometallic reference materials from other sources to prepare the check standard.
• Quality assurance and quality control (15, as needed):
  • 15.1 Confirm the validity of the instrument and the test process by analyzing quality control (QC) samples.
    • 15.1.1 If the testing equipment includes quality control and quality assurance protocol documents, they may be used to confirm the reliability of the test results.
    • 15.1.2 If the testing equipment does not include quality control and quality assurance protocol documents, quality assurance control may be carried out with reference to Appendix A.
  • 15.2 It is recommended that users who already have a protocol make Appendix A a mandatory part for one or more parties to the protocol.

9. Qualitative and Quantitative Determination and Calculation Formulas

• 16.1 Calculate the sample concentration according to formula (2). Usually, ICP-AES instrument software will automatically calculate the result. C = S × (W₁ + M + B) / M …(2) Where: C— concentration of the analyte element in the sample, % (mass fraction); S— concentration of the analyte element in the test sample solution, % (mass fraction); M— sample mass, g; W₁—diluent mass, g; B— base oil mass, g (the original text source-text extraction is "Wy base oil mass, 80", requires confirmation against the source standard (source-text extraction)).
• 16.2 For each element, report the result to three significant figures.
• Interferences (5):
  • 5.1 Spectral interferences: when measuring at the wavelengths listed in Table 1, there are no known spectral interferences among these elements. However, when spectral interferences occur due to the presence of other interfering elements or because other spectral lines are selected, correct spectral interferences using the method specified in GB/T 17476.
  • 5.2 Viscosity index improver interference: those viscosity index improvers that can be used in multigrade lubricating oils will cause measurement deviations; through specific dilution and the use of an internal standard, such deviations can be reduced to a negligible extent.

10. Precision

• 17.1 The precision of this test method was determined by statistical analysis of results among laboratories. Fourteen laboratories analyzed twelve identical samples; most laboratories used three dilution ratios: 1%, 3%, and 5%. The method used mixed xylene, o-xylene, and kerosene as diluents. The organometallic compound standards used by most laboratories were metal sulfonates. Most laboratories used peristaltic pumps, and nearly half of the laboratories performed background subtraction. The sample set consisted of eight oils, of which five were multigrade oils and four were composite additives. In the interlaboratory study for the determination of molybdenum, eleven laboratories determined molybdenum in ten lubricating oil samples and eight additive samples; all laboratories used an internal standard and a peristaltic pump.
• 17.2 Judge the reliability of the test results according to the following provisions (95% confidence level).
  • 17.2.1 Repeatability r: the difference between two results obtained by the same operator using the same instrument under the same operating conditions on the same sample shall not exceed the repeatability requirement specified in Table 2; typical values are shown in Table 4.
  • 17.2.2 Reproducibility R: the difference between two results obtained by different operators in different laboratories on the same sample shall not exceed the reproducibility requirement specified in Table 3; typical values are shown in Table 4.
• Table 2 Repeatability requirements (unit: % (mass fraction)):
  • Element Ba: lubricating oil 0.011; additive 0.20
  • Element B: lubricating oil 0.0017; additive 0.033
  • Element Ca: lubricating oil 0.0145(X+0.152) (the original text source-text extraction is "0.0145 (X¥.0.152)9.67", requires confirmation against the source standard (source-text extraction)); additive 0.0363X (the original text source-text extraction is "0. 0363.1", requires confirmation against the source standard (source-text extraction))
  • Element Cu: lubricating oil 0.0008; additive 0.0054
  • Element Mg: lubricating oil 0.0159X+0.7 (the original text source-text extraction is "Q.0159XD.7", requires confirmation against the source standard (source-text extraction)); additive 0.0473X
  • Element Mo: lubricating oil 0.002175X+0.486 (the original text source-text extraction is "0.002175 X.486", requires confirmation against the source standard (source-text extraction)); additive 0.01114X+0.805 (the original text source-text extraction is "0.01114X0805", requires confirmation against the source standard (source-text extraction))
  • Element P: lubricating oil 0.0264X; additive 0.0313(X+0.294)
  • Element S: lubricating oil 0.016; additive 0.14
  • Element Zn: lubricating oil 0.0212(X+0.0041); additive 0.035
  • Note: X is the average of two replicate determination results.
• Table 3 Reproducibility requirements (unit: % (mass fraction)):
  • Element Ba: lubricating oil 0.019; additive 0.60
  • Element B: lubricating oil 0.0035; additive 0.016
  • Element Ca: lubricating oil 0.0208(X+0.152) (the source text source-text extraction is "0. 0208 (k+0.152) %5", requires confirmation against the source standard (source-text extraction)); additive 0.114X
  • Element Cu: lubricating oil 0.0017; additive 0.016
  • Element Mg: lubricating oil 0.0624X (the source text source-text extraction is "0.0624)$", requires confirmation against the source standard (source-text extraction)); additive 0.196X (the source text source-text extraction is "a.1g6x", requires confirmation against the source standard (source-text extraction))
  • Element Mo: lubricating oil 0.005904X+1.480 (the source text source-text extraction is "0.005904X1.480g", requires confirmation against the source standard (source-text extraction)); additive 0.650067+0.8 (the source text source-text extraction is "0,6500670.8", requires confirmation against the source standard (source-text extraction))
  • Element P: lubricating oil 0.101X; additive 0.115(X+0.294)
  • Element S: lubricating oil 0.061; additive 0.372
  • Element Zn: lubricating oil 0.0694(X+0.0041); additive 0.115
  • Note: X is the average of two independent results.
• Table 4 Precision at typical concentrations (unit: % (mass fraction)): the source text source-text extraction is severely noisy, the correspondence between concentration points and the corresponding repeatability/reproducibility values cannot be reliably reconstructed, requires confirmation against the source standard (source-text extraction). The identifiable concentration ranges include: 0.01–0.02, 0.11–0.13, 0.012–0.18, 0.8–4.1, 0.05–0.14, 0.35–0.82, 0.005–0.05, 0.043–0.50, 0.05–0.12, 0.7–1.3, 0.3–0.8, 3.0–3.2, 0.05–0.13, 0.7–1.4, etc.

11. Report

• 16.2 For each element, report the result to three significant figures.
• Appendix B Guidance on analytical operations (informative appendix) relevant requirements:
  • B.18 Report results according to the number of significant figures specified in this standard.
  • B.19 Dilute the calibration standard and test sample by the same dilution factor, and the dilution factor shall be within the range specified in the method.
  • B.20 Use an internal standard as specified in this method.
• Other report format requirements: not provided in the available source.

12. Normative references

• GB/T 4756 Petroleum liquids — Manual sampling (GB/T 4756-1998, eqv ISO 3710:1988) (the source text source-text extraction is "ISO 3710: 1988", requires confirmation against the source standard (source-text extraction))
• GB/T 17476 Standard test method for determination of additive elements, wear metals, and contaminants in used lubricating oils and determination of selected elements in base oils (inductively coupled plasma atomic emission spectrometry)
• SH/T 0172 Determination of sulfur content in petroleum products (high temperature method)
• SH/T 0631 Standard test method for determination of barium, calcium, phosphorus, sulfur, and zinc in lubricating oils and additives (X-ray fluorescence spectrometry) (the source text source-text extraction is "×-ray fluorescence spectrometry", requires confirmation against the source standard (source-text extraction))
• ASTM D4307 Preparation of liquid mixtures used as analytical standards
• ASTM D6299 Methods for evaluating analytical measurement system performance using statistical quality assurance techniques
• Appendix A references: ASTM D6299, ASTM MNL7 (manual for data presentation and control chart analysis)
• Appendix B references: not provided in the available source as a separate list of references

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