SH/T 0472-1992 Determination of Trace Metal Content in Synthetic Aviation Lubricating Oils (Atomic Absorption Method)

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Card type: Test method

1. Method number / Full name / English name / Replacement relationship

• Standard number: SH/T 0472-92
• Full name: Determination of Trace Metal Content in Synthetic Aviation Lubricating Oils (Atomic Absorption Method)
• English name: not provided in the available source
• Replacement relationship: replaces SY 4034-84
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• This standard specifies the method for the determination of trace metal content in synthetic aviation lubricating oils.
• This standard is applicable to the determination of trace copper, iron, magnesium, nickel, chromium and silver in unused synthetic aviation lubricating oils.
• Not applicable: not provided in the available source (only explicitly applicable to "unused" synthetic aviation lubricating oils).

3. Method principle

Dilute the sample with a mixture of butyl acetate and glacial acetic acid as solvent, directly spray into an air-acetylene flame for atomic absorption spectrometry, and quantify by the working curve method.

4. Reagents and materials (purity / preparation)

4.1 Reagents

• 3.1 Copper oxide: high purity or spectral purity
• 3.2 Ferric oxide: high purity or spectral purity
• 3.3 Magnesium oxide: high purity or spectral purity
• 3.4 Nickel sesquioxide: high purity or spectral purity
• 3.5 Chromium metal: high purity or spectral purity
• 3.6 Silver nitrate: high purity or spectral purity
• 3.7 Butyl acetate
• 3.8 Glacial acetic acid
• 3.9 Hydrochloric acid: guaranteed reagent grade
• 3.10 Nitric acid: guaranteed reagent grade
• 3.11 Deionized water: the allowable content of the metals to be determined shall be such that it does not affect the determination

4.2 Preparation of standard solutions (5.1.1)

• 5.1.1.1 1000 μg/mL Copper standard solution: weigh 0.1252g of copper oxide that has been dried at 120℃ for 2h and cooled to room temperature into a beaker, add 10mL 1:1 hydrochloric acid solution, heat to dissolve, after cooling transfer to a 100mL volumetric flask, dilute to the mark with deionized water, and mix well.
• 5.1.1.2 1000 μg/mL Iron standard solution: weigh 0.1430g of ferric oxide that has been dried at 120℃ for 2h and cooled to room temperature into a beaker, add 10mL 1:1 hydrochloric acid solution, heat to dissolve, after cooling transfer to a 100mL volumetric flask, dilute to the mark with deionized water, and mix well.
• 5.1.1.3 1000 μg/mL Magnesium standard solution: weigh 0.1659g of magnesium oxide that has been ignited at 800℃ for 2h and cooled to room temperature into a beaker, add 10mL 1:1 hydrochloric acid solution, heat to dissolve, after cooling transfer to a 100mL volumetric flask, dilute to the mark with deionized water, and mix well.
• 5.1.1.4 1000 μg/mL Nickel standard solution: weigh 0.409g of nickel sesquioxide that has been dried at 120℃ for 2h and cooled to room temperature into a beaker, add 3mL 1:1 nitric acid solution and 10mL 1:1 hydrochloric acid solution, heat to dissolve, after cooling transfer to a 100mL volumetric flask, dilute to the mark with deionized water, and mix well. (The sample weight "0._4098" requires confirmation against the source standard (source-text extraction))
• 5.1.1.5 1000 μg/mL Chromium standard solution: weigh 0.1000g of chromium metal into a beaker, add 10mL 1:1 hydrochloric acid solution, heat to dissolve, after cooling transfer to a 100mL volumetric flask, dilute to the mark with deionized water, and mix well.
• 5.1.1.6 1000 μg/mL Silver standard solution: weigh 0.1575g of silver nitrate and dissolve in 10mL of deionized water, transfer to a 100mL brown volumetric flask, dilute to the mark with deionized water, and mix well.
• 5.1.1.7 50 μg/mL Mixed standard solution: take 1000 μg/mL each of the copper, iron, magnesium, nickel, and chromium standard solutions 2.50mL and add to the same 50mL volumetric flask, dilute to the mark with deionized water, and mix well. This solution should be prepared immediately before use.
• 5.1.1.8 50 μg/mL Silver standard solution: take 1000 μg/mL of silver standard solution 2.50mL into a 50mL volumetric flask, dilute to the mark with deionized water, and mix well. This solution should be prepared immediately before use.

4.3 Preparation of mixed solvent (5.1.2)

Measure 300mL of butyl acetate and 200mL of glacial acetic acid in a 500mL graduated cylinder, add to a 500mL reagent bottle, and mix well.

5. Instruments and equipment

• 4.1 Atomic absorption spectrophotometer: equipped with a corrosion-resistant adjustable nebulizer, with scale expansion (or direct concentration readout) and extended integration time functions, and equipped with copper, iron, magnesium, nickel, chromium and silver hollow cathode lamps. Uses an air-acetylene flame.
• 4.2 Balance: capable of accurately weighing to 0.0001g
• 4.3 Pipettes: 1, 5mL
• 4.4 Volumetric flasks: 25, 50, 100mL
• 4.5 Graduated cylinder: 500mL
• 4.6 Beakers: 25, 50mL
• 4.7 Reagent bottle: 500mL

6. Recommended operating conditions

• 5.1.3 Select instrument conditions: spray the solution containing the metals to be determined, prepared with the mixed solvent (for preparation method see 5.2.1), into the air-acetylene flame, refer to the flame type in the appendix to establish the optimal fuel-to-oxidant ratio for each metal element, and select the instrument parameters for the determination of each metal element (such as lamp current, amplification gain, slit width, burner height position, and sample uptake rate), so that the instrument's recording system gives the maximum absorbance A at the measurement wavelength listed in Appendix A, and select appropriate scale expansion and integration time according to the content range to be determined, and record for later use.
• Appendix A (supplementary document) operating conditions:

7. Sampling and sample preparation

• 5.3.1 Pretreatment of the test sample: use a pipette to draw 2.5mL of the lubricating oil test portion to be analyzed, place into a 25mL volumetric flask, accurate to 0.0?g (the weighing precision is illegible in the source transcription and remains unverified), dilute to the mark with the mixed solvent of butyl acetate and glacial acetic acid, and mix well.

8. Analysis procedure

8.1 Preparatory work

• 5.1.1 Prepare standard solutions (see Section 4)
• 5.1.2 Prepare mixed solvent (see Section 4)
• 5.1.3 Select instrument conditions (see Section 6)

8.2 Plot the working curve

• 5.2.1 Preparation of standard series
  • 5.2.1.1 0.1～1.0 μg/mL Copper, iron, magnesium, nickel, chromium standard series: take 50 μg/mL of the mixed standard solution 0.05, 0.15, 0.25, 0.35 and 0.50mL and add respectively to five 25mL volumetric flasks, dilute to the mark with the mixed solvent of butyl acetate and glacial acetic acid, and mix well. Note: The water content in the standard series should not exceed 2%.
  • 5.2.1.2 0.1～1.0 μg/mL Silver standard series: take 50 μg/mL of the silver standard solution 0.05, 0.15, 0.25, 0.35 and 0.50mL and add respectively to five 25mL volumetric flasks, dilute to the mark with the mixed solvent of butyl acetate and glacial acetic acid, and mix well. Note: The water content in the standard series should not exceed 2%.
• 5.2.2 Plot the working curve: according to the instrument conditions selected in 5.1.3, at the measurement wavelengths listed in Appendix A, zero the instrument with the mixed solvent of butyl acetate and glacial acetic acid as blank, and measure the absorbance A of the standard series of each metal element in 5.2.1. Plot the working curve for each element with the absorbance A of each metal element as the ordinate and the corresponding concentration C as the abscissa. Note: When the concentration of magnesium is greater than 0.5 μg/mL, the working curve becomes curved.

8.3 Determination of test sample

• 5.3.1 Pretreatment of the test sample (see Section 7)
• 5.3.2 Determination of the test portion: according to the instrument conditions selected in 5.1.3, immediately after measuring the standard series of each metal element, measure the absorbance A of the treated test portion solution. Based on the absorbance A, read the concentration C of the metal element to be determined in the treated test portion from the working curve of each metal element (instruments with direct concentration readout may also use direct concentration readout).

9. Qualitative and quantitative determination and calculation formula

• 6.1 Calculate the metal content per gram of oil X (μg/g) respectively according to the following formula: X = C × V / m Where:
  • C — concentration of the metal in the treated test portion, μg/mL
  • V — volume of the treated test portion, mL
  • m — mass of the test portion, g
• 6.2 Report: report the content of each metal determined as the arithmetic mean of two parallel determination results, in units of μg/g, reported to the nearest 0.1 units.

10. Precision

• 7.1 Repeatability: the difference between two results obtained by the same operator in repeated determinations shall not exceed the following values:

• Reproducibility: not provided in the available source

11. Report

• 6.2 Report the content of each metal determined as the arithmetic mean of two parallel determination results, in units of μg/g, reported to the nearest 0.1 units.
• Other report format requirements: not provided in the available source

12. Reference documents

• Not provided in the available source (the main text does not list a normative reference document list)

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