GB/T 37160-2019 Determination of trace metal elements in heavy distillate oils, residual oils and crude 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: GB/T 37160—2019
• Chinese title: Determination of trace metal elements in heavy distillate oils, residual oils and crude oils — Inductively coupled plasma atomic emission spectrometry
• English title: Standard test method for determination of trace metals in heavy distillate, residual oil and crude oil—Inductive coupled plasma optical emission spectrometry (ICP-OES)
• Replacement relationship: not provided in the available source (the foreword only states that it was drafted in accordance with GB/T 1.1—2009, and does not mention replacing any standard)
• Publication / implementation: published on 2019-03-25, implemented on 2019-10-01
• Secretariat: National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280)
• Drafting organizations: Petrochemical Research Institute of PetroChina Company Limited, Research Institute of Petroleum Processing of China Petroleum & Chemical Corporation
• Main drafters: He Jing, Yang Xiaoyan, Wang Jieming, Sun Lijun, Zhang Jingyuan, Yao Yuan, Chen Yang, Liu Jingxin, Huo Mingchen, He Lina, Sun Xinchan

2. Scope of application and non-applicability

• Applicable: use ICP-OES to determine the content of aluminum, calcium, iron, potassium, magnesium, manganese, molybdenum, sodium, nickel, lead, vanadium and zinc elements in heavy distillate oils, residual oils and crude oils.
• Description of applicable objects (note): heavy distillate oil refers to components distilled under reduced pressure, such as heavy diesel, wax oil, catalytic feedstock, vacuum gas oil, etc.
• Concentration range: see Table 1 (determination concentration range and recommended wavelength for each element).
• Not applicable: no explicit "not applicable" clause is provided in the available source. The source mentions that "for samples whose concentration range exceeds the specified range, this standard may also be used for determination, but its precision has not been verified" (12.1).

3. Method principle

Weigh a certain amount of sample into a quartz cup, and add sulfuric acid according to the sample amount. Place the quartz cup containing the sample on an electric hot plate and heat to burn off organic matter, then transfer it into a muffle furnace and burn off carbon deposits under the conditions of 550 ℃. Dissolve the sample ash with aqua regia, add scandium internal standard element standard solution, and determine with an inductively coupled plasma atomic emission spectrometer.

4. Reagents and materials (purity / preparation)

• 4.1 (original text 5.1) reagent purity: all reagents are analytical grade or higher purity; when using reagents of other grades, check whether the purity is sufficient to ensure that the accuracy of the results is not affected.
• Hydrochloric acid (5.2): mass fraction 36%～38%. Warning: corrosive acid, can cause burns.
• Nitric acid (5.3): mass fraction 65%～68%. Warning: corrosive acid, can cause burns.
• Aqua regia (5.4): nitric acid and hydrochloric acid mixed in a volume ratio of 1∶3, and must be freshly prepared before each use. Warning: corrosive acid, can cause burns.
• Sulfuric acid (5.5): mass fraction 95%～98%. Warning: corrosive acid, can cause burns.
• Water (5.6): deionized water, meeting the grade two water requirements in GB/T 6682—2008.
• Scandium internal standard element standard solution (5.7): concentration 1000 mg/L, commercially available standard solution may be used.
• Metal element standard solution (5.8): aluminum, calcium, iron, potassium, magnesium, manganese, molybdenum, sodium, nickel, lead, vanadium and zinc concentrations are respectively 1000 mg/L, commercially available standard solution may be used.
• Scandium internal standard element standard stock solution (8.2.1): 100 mg/L. Pipette 10 mL 1000 mg/L scandium standard solution (5.7) into a 100 mL volumetric flask, add 5 mL hydrochloric acid (5.2), dilute to volume with water and mix well, store in a 100 mL plastic bottle. Shelf life one month.
• Scandium internal standard element standard solution (8.2.2): 10 mg/L. Pipette 10 mL 100 mg/L scandium stock solution (8.2.1) into a 100 mL volumetric flask, add 5 mL hydrochloric acid, dilute to volume with water and mix well, store in a 100 mL plastic bottle. Shelf life one month.
• Metal element standard stock solution A (8.3.1): respectively pipette 10 mL 1000 mg/L of aluminum, calcium, iron, potassium, magnesium, manganese standard solution (5.8) into a 100 mL volumetric flask, add 4 mL aqua regia (5.4), dilute to the mark with water, to obtain concentration 100 mg/L. Shelf life one month.
• Metal element standard stock solution B (8.3.2): respectively pipette 10 mL 1000 mg/L of molybdenum, sodium, nickel, lead, vanadium, zinc standard solution (5.8) into a 100 mL volumetric flask, add 4 mL aqua regia (5.4), dilute to the mark with water, to obtain concentration 100 mg/L. Shelf life one month.
• Blank solution (8.4): pipette 1 mL 100 mg/L scandium internal standard stock solution (8.2.1) into a 100 mL volumetric flask, add 4 mL aqua regia, dilute to the mark with water, shake well, to obtain the standard blank solution. Shelf life one month.
• 5 mg/L metal element standard working solution (8.5): respectively pipette 1 mL 100 mg/L scandium internal standard stock solution (8.2.1), 5 mL stock solution A (8.3.1), 5 mL stock solution B (8.3.2) and 4 mL aqua regia into a 100 mL volumetric flask, dilute to the mark with water, shake well, to obtain a standard working solution of aluminum, calcium, iron, potassium, magnesium, manganese, molybdenum, sodium, nickel, lead, vanadium and zinc at concentration 5 mg/L. Shelf life one month.
• 10 mg/L metal element standard working solution (8.6): respectively pipette 1 mL 100 mg/L scandium internal standard stock solution (8.2.1), 10 mL stock solution A (8.3.1), 10 mL stock solution B (8.3.2) and 4 mL aqua regia into a 100 mL volumetric flask, dilute to the mark with water, shake well, to obtain a standard working solution of aluminum, calcium, iron, potassium, magnesium, manganese, molybdenum, sodium, nickel, lead, vanadium and zinc at concentration 10 mg/L. Shelf life one month.

5. Instruments and equipment

• 4.1 Inductively coupled plasma atomic emission spectrometer (ICP-OES): the wavelength range can cover 160 nm～760 nm, with sufficient resolving power, and can satisfy the determination of aluminum, calcium, iron, potassium, magnesium, manganese, molybdenum, sodium, nickel, lead, vanadium, zinc and scandium.
• 4.2 Balance: accurate to 0.001 g.
• 4.3 Quartz cup: 250 mL, recommended cup body diameter 7 cm.
• 4.4 Stirring rod: quartz material, length exceeding the cup mouth by 5 cm or more.
• 4.5 Watch glass: quartz material, used to cover the quartz cup, recommended diameter 8 cm or more.
• 4.6 Volumetric flask: 25 mL and 100 mL.
• 4.7 Pipette: 1 mL, 5 mL and 10 mL.
• 4.8 Graduated cylinder: 2 mL, 5 mL and 10 mL.
• 4.9 Plastic bottle: narrow-mouth with screw thread, 100 mL, suitable for long-term storage of dilute acid solutions.
• 4.10 Muffle furnace: operating temperature can reach 600 ℃, temperature control accuracy ±5 ℃.
• 4.11 Electric hot plate: adjustable temperature, working temperature can reach 500 ℃.
• 4.12 Crucible tongs: for gripping the quartz cup.
• 4.13 Dropper: 2 mL.
• 4.14 Oven: capable of controlling temperature at 50 ℃～60 ℃.
• 4.15 Water bath: capable of controlling temperature at 50 ℃～100 ℃.

6. Recommended operating conditions

• Ashing temperature: 550 ℃ (muffle furnace, 8.7.4).
• Ashing time: generally 5 h; for samples that are more difficult to ash, it may be extended (8.7.4).
• Aqua regia dissolution: add 10 mL aqua regia to dissolve the residue and rinse the stirring rod, heat on an electric hot plate and evaporate to about 1 mL (8.7.5).
• Instrument wavelength range: 160 nm～760 nm (4.1).
• Recommended wavelengths and determination concentration ranges: see Table 1 (see Section 9).
• The wavelengths provided in Table 1 are for user reference only; users may select other suitable wavelengths for determination according to the instrument used and the sample conditions.

7. Sampling and sample preparation

• 7.1 Unless otherwise specified, all laboratory samples shall be sampled according to the methods specified in GB/T 4756, GB/T 27867.
• 7.2 The sample weighed shall be representative; viscous samples may be heated to make them flow freely. For most samples, heating in a water bath can give satisfactory results; samples with excessively high viscosity need to be heated on an electric hot plate until they flow freely.
• 7.3 For some water-containing samples, they should be heated on an electric hot plate with a watch glass covering, and the temperature should be raised slowly to evaporate water.
• 7.4 For samples with relatively low or excessively high content of the elements to be determined, the sample amount may be increased or decreased.
• Sample solution preparation (8.7):
  • 8.7.1 Weigh a certain amount of sample into a quartz cup (4.3); the sample amount is usually 5 g～10 g, accurate to 0.001 g, and cover with a watch glass (4.5).
  • 8.7.2 Measure 2 mL sulfuric acid (5.5), and using a dropper (4.13), add it dropwise to the sample from between the watch glass and the mouth of the quartz cup until the reaction gradually weakens and no more bubbles are generated, then add all the remaining sulfuric acid. Note 1: The dropper may be inserted between the watch glass and the mouth of the quartz cup to control the reaction rate. Note 2: 2 mL sulfuric acid is suitable for treating samples of about 10 g; larger amounts of sample require more sulfuric acid.
  • 8.7.3 Place the quartz cup covered with a watch glass on an electric hot plate (4.11) and heat it, raising the temperature slowly to avoid splashing; if large lumps of coking appear, they may be broken up with a stirring rod (4.4), and the stirring rod should be left in the quartz cup so that the watch glass can still cover most of the cup mouth. The stirring rod should remain in the quartz cup until after step 8.7.5 before being removed.
  • 8.7.4 After the sample stops smoking and has completely coked, place the covered quartz cup together with the stirring rod into a 550 ℃ muffle furnace (4.10) for ashing, ensuring that the carbon deposit is completely ashed, then remove and cool to room temperature.
  • 8.7.5 Add 10 mL aqua regia (5.4) to the quartz cup to dissolve the residue and rinse the stirring rod, place it on the electric hot plate and heat it, and when the solution has evaporated to about 1 mL remaining, remove and cool to room temperature. If the sample has not completely dissolved, cool the test solution, add another 10 mL aqua regia, and evaporate again.
  • 8.7.6 Quantitatively transfer the test solution in the quartz cup with water (5.6) to a 25 mL volumetric flask (4.6), use a 5 mL pipette (4.7) to transfer 2.5 mL 10 mg/L scandium internal standard element standard solution (8.2.2) into the volumetric flask, dilute to the mark with water, and shake well for testing.
  • 8.7.7 Prepare a reagent blank according to 8.7.2～8.7.6.

8. Analysis Procedure

• 8.1 Quartz cup cleaning: Clean the quartz cup before each use. Measure 10 mL hydrochloric acid (5.2) into the quartz cup, place it on an electric hot plate (4.11) and boil, rinse clean with water (5.6), and dry for use.
• 9.1 Start ICP-OES and ignite the plasma torch, and wait for the instrument to stabilize. Sequentially aspirate the blank solution (8.4), the 5 mg/L metal element standard working solution (8.5), and the 10 mg/L metal element standard working solution (8.6), and establish a standard working curve for each element to be determined. Table 1 lists the measurement concentration range and spectral line wavelength for each element to be determined. If spectral line overlap occurs, other wavelengths may also be used. The selected wavelength should maintain sufficient sensitivity to achieve the necessary detection limit.
• 9.2 Sequentially aspirate the reagent blank (8.7.7) and the test solution (8.7.6), determine the content of each element in the test solution, and calculate the final result for each element to be determined in the sample based on the sample mass and constant volume.
• 9.3 If the concentration of one or more elements is relatively high and exceeds the concentration range of the calibration curve, dilute the test solution with the blank solution (8.4) to within the reading range of the calibration curve and re-measure.
• Safety matters (6): This standard requires the use of high-pressure gases and corrosive acids. During the use of nitric acid, hydrochloric acid, sulfuric acid, and aqua regia, appropriate personal protective equipment should be provided, and special tools should be used when opening high-pressure gases such as argon and compressed air.
• Preparation work warning (8): Corrosive acids are required in the preparation work. During the use of nitric acid, hydrochloric acid, sulfuric acid, and aqua regia, operations should be carried out in a fume hood, and gloves and goggles should be worn.
• Sample solution preparation warning (8.7): Because the addition of sulfuric acid causes a violent reaction, all sulfuric acid treatment should be carried out in a fume hood, with goggles and gloves worn and the fume hood sash pulled low.

9. Qualitative and Quantitative Determination and Calculation Formulas

• Table 1 Element measurement concentration range and recommended wavelengths:

• Calculation (10):

  • 10.1 After the operator inputs the sample mass and dilution volume, the calculation is automatically performed by the calculation software.

  • 10.2 Manual calculation of the sample element content C is carried out according to formula (1):

    C = R·V·D / m ……………………（1）

    Where:

    • C——— element content of the sample, in milligrams per kilogram (mg/kg);
    • R——— element content in the test solution, in milligrams per liter (mg/L);
    • V——— constant volume, in milliliters (mL);
    • D——— dilution factor;
    • m——— sample mass, in grams (g).
• Expression of results (11): The measurement results for each element content are retained to two decimal places, and the results are expressed in mg/kg.

10. Precision

• 12.1 Overview: The precision of this standard is determined according to GB/T 6683 through interlaboratory statistical analysis results. It was obtained through statistical analysis results from 6 laboratories on 4 crude oils, 3 heavy distillate oils, 1 residual oils, and 4 standard oils, totaling 12 samples. For samples whose concentration range exceeds the specified range, this standard may also be used for determination, but its precision has not been verified. The reliability of test results is judged according to the following provisions (95% confidence level).
• 12.2 Repeatability: For the same operator, in the same laboratory, using the same instrument, according to the same test method, conducting continuous determinations on the same sample, the difference between the two results obtained shall not be greater than the value specified in Table 2.
• 12.3 Reproducibility: For different operators, in different laboratories, using different instruments, according to the same test method, testing the same sample, the difference between the two single and independent test results obtained shall not exceed the value specified in Table 2.
• 12.4 Bias: Because there is no suitable reference material, the bias of this standard cannot be determined.
• Table 2 Precision:

Note: m——— arithmetic mean of two determination results, mg/kg.

11. Report

No independent "Report" section is provided in the available source. The relevant result expression requirements are given in Section 11 (Expression of Results): the measurement results for each element content are retained to two decimal places, and the results are expressed in mg/kg.

12. Referenced Documents

Normative referenced documents (Chapter 2):

• GB/T 4756 Petroleum liquids — Manual sampling
• GB/T 6682—2008 Water for analytical laboratory use — Specification and test methods
• GB/T 27867 Petroleum liquids — Automatic pipeline sampling

References (References section):

• [1] GB/T 6683 Petroleum products — Determination of precision data in relation to methods of test

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