SH/T 0617-1995 Determination of Lead Content in Lubricating Oils (Atomic Absorption Spectrometry)

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Card type: Test method

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

• Standard number: SH/T 0617-95
• Chinese full title: Determination of Lead Content in Lubricating Oils (Atomic Absorption Spectrometry)
• English title: not provided in the available source
• Replacement relationship: not provided in the available source (only “(2〕) [unreadable year] confirmation” is seen, suspected to be “×× year confirmation”, requires confirmation against the source standard (source-text extraction))
• Approval/implementation: approved by China Petrochemical Corporation 1995-06-15, implemented on 1995-10-01
• Adoption relationship: non-equivalent adoption of German national standard DIN 51827-89 “Determination of Lead Content in Lubricating Greases (Atomic Absorption Spectrometry)”

2. Scope of application and non-applicability

• Applicable to new and used lubricating oils.
• Not applicable: not provided in the available source.

3. Method principle

The sample is ashed at high temperature, the ash is dissolved with nitric acid to prepare a nitric acid solution of the sample, and the absorbance of the standard solution and the sample solution is measured with an atomic absorption spectrometer at the wavelength 283.3 nm (written in the source as 283.3=, requires confirmation against the source standard (source-text extraction)) to determine the lead content in the sample.

4. Reagents and materials (purity / preparation)

• 4.2.1 Air: compressed air, purified to remove oil and water.
• 4.2.2 Acetylene gas: cylinder-packed, purity not lower than 99.9%.
• 4.2.3 Distilled water: double-distilled water.
• 5.1 Lead acetate (Pb(CH₃COO)₂·3H₂O): melting point 75 ℃ (source text “7540”, requires confirmation against the source standard (source-text extraction)), or high-purity lead granules (99.999%).
• 5.2 Nitric acid: guaranteed reagent grade, prepared as 5% (m/m) nitric acid solution.
• 5.3 Ammonium nitrate: analytical reagent grade, prepared as 100 g/L ammonium nitrate solution (source text “IOOg/L [garbled nitrate-solution name]”, requires confirmation against the source standard (source-text extraction)).
• 6.1 Blank solution: add 20 mL 5% (m/m) nitric acid solution to a 1000 mL volumetric flask, dilute to the mark with water, and mix well.
• 6.2 Lead stock solution (1 mg/mL):
  • Lead acetate method: weigh 1.8310 g (to the nearest 0.1 mg) of lead acetate into a 250 mL beaker, add distilled water to dissolve, transfer to a 1000 mL volumetric flask, add distilled water to the mark, and mix well.
  • High-purity lead granule method: weigh 1.0000 g of high-purity lead granules, dissolve with 1:2 (volume ratio) nitric acid solution, transfer with distilled water to a 1000 mL volumetric flask, add distilled water to the mark, and mix well.
• 6.3 Standard working solution: accurately pipette 0.1, 0.5, 1.0, 2.0 and 5.0 mL of lead standard stock solution into 100 mL volumetric flasks, dilute to the mark with blank solution, and mix well to obtain lead standard working solutions with lead contents of 1, 5, 10, 20 and 50 µg/mL (source text “[unreadable character]mL”, requires confirmation against the source standard (source-text extraction)), and draw a working curve.

5. Instruments and equipment

• 4.1.1 Atomic absorption spectrophotometer: wavelength range 190～900 nm (source text “190 - 900=”, requires confirmation against the source standard (source-text extraction)); any atomic absorption spectrophotometer capable of measuring the lead analytical line (283.3 nm) within the absorbance range 0.1～0.5 may be used.
• 4.1.2 Lead hollow cathode lamp.
• 4.1.3 High-temperature furnace: capable of maintaining a temperature of 550 ℃±25 ℃.
• 4.1.4 Balance: sensitivity 0.1 mg.
• 4.1.5 Quartz crucible: 50 mL.
• 4.1.6 Volumetric flask: 100, 1000 mL.
• 4.1.7 Pipette: 2, 5 mL, with graduations of 0.01, 0.1 mL respectively.
• 4.1.8 Beaker: 250 mL.

6. Recommended operating conditions

Adjust the instrument according to the conditions in Table 1.

Table 1 Instrument working conditions

Note: The performance of different instrument models varies; the above conditions are for reference only.

(The units for “Slit”, “Burner height”, “Extraction amount”, and “Expansion factor” in the table header are unclear in the source text, requires confirmation against the source standard (source-text extraction))

7. Sampling and sample preparation

• 6.4.1 Before weighing, heat the sample to 50～60 ℃ and stir thoroughly to mix evenly.
• 6.4.2 Weigh 2 g of sample into a quartz crucible (to the nearest 0.1 mg), burn it according to GB/T 508, then place it in a high-temperature furnace and ash at 550 ℃±25 ℃ for about 2 h.
  • Note: The ash remaining in the quartz crucible should not contain any unburned carbon. If a difficult-to-ash sample is encountered, add a few drops of 100 g/L ammonium nitrate solution if necessary.
• 6.4.3 After the ash has cooled, add 5 mL 5% (m/m) nitric acid solution, and place on an electric furnace to heat and dissolve the ash until it is completely dissolved and about 0.5 mL of sample solution remains.
• 6.4.4 Transfer the above solution to a 100 mL volumetric flask, dilute to the mark with distilled water, and mix well.

8. Analytical procedure

• 7.2.1 Set zero with the blank solution.
• 7.2.2 Measure the absorbance of the sample solution.
• 7.2.3 Measure the absorbance of the standard working solution closest to the sample solution.
• 7.2.4 Measure the absorbance of the sample solution.
• 7.2.5 Measure the absorbance of the standard working solution closest to the sample solution.
• 7.2.6 Check the zero point with the blank solution.
• 7.2.7 Repeat the measurement of the absorbance of the standard working solution and the sample solution according to steps 7.2.1～7.2.6, and take the arithmetic mean of the absorbances of two repeated measurements as the measured value.
• Note ①: The standard working solution and the sample solution should be prepared at the same time and their absorbances measured on the same day.
• Note ②: For high-content samples exceeding the measurement range, the measurement can be carried out by reducing the sample weight, increasing the dilution volume, and shortening the optical path length, etc.
• Note ③: The best linear range of this standard is 5～50 mgPb/kg.

9. Qualitative and quantitative determination and calculation formula

The lead content in the sample X[% (m/m)] is calculated according to the following formula:

X = (A₁ / A₂) × (C · V / m) × 100

Where:

• A₁ — average absorbance of the sample solution;
• A₂ — average absorbance of the standard working solution close to the sample solution;
• C — concentration of the standard working solution corresponding to A₂, mg/L;
• V — dilution volume, mL;
• m — mass of the sample, g.

Note: The above formula is applicable only when the standard working curve of lead standard working solution concentration versus absorbance is linear.

(The formula in the source text is laid out as a fraction; the symbols after source-text extraction are disordered. The above is organized according to the meanings of the symbols in the source text, requires confirmation against the source standard (source-text extraction))

10. Precision

Judge the reliability of the measurement results according to the following provisions (95% confidence level).

• 9.1 Repeatability: the difference between two results obtained by the same operator in repeated measurements shall not exceed the repeatability specified in Table 2.
• 9.2 Reproducibility: the difference between two results submitted by different laboratories shall not exceed the reproducibility specified in Table 2.

Table 2 Precision provisions % (m/m)

Note: X is the arithmetic mean of two measurement results.

11. Report

Take the arithmetic mean of two repeated measurement results as the measurement result, rounded to three decimal places.

12. Referenced documents

• GB/T 508 Determination of Ash in Petroleum Products

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