SH/T 0027-1990 Determination of magnesium content in additives (atomic absorption spectrometry)

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

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

• Standard number: SH/T 0027-90
• Chinese full title: Determination of magnesium content in additives (atomic absorption spectrometry)
• English name: not provided in the available source
• Replacement relationship: not provided in the available source
• Other: The standard text is marked "(2〕[unreadable year character]) year confirmed)", suspected to be "(20XX) year confirmed", the specific year number requires confirmation against the source standard (source-text extraction); approval date 991-03-27 (suspected to be 1991-03-27, requires confirmation against the source standard (source-text extraction)); implementation date 1992-04-01.

2. Scope of application and non-application

• This standard specifies a method for the determination of magnesium content in additives by atomic absorption spectrometry.
• Applicable to the determination of petroleum additives with a magnesium content of 1%～10%.
• Under the specified conditions, coexisting metal elements calcium, barium, zinc and non-metal elements sulfur, phosphorus, etc. do not interfere with the determination.
• Non-applicable scope: not provided in the available source.

3. Method principle

The sample is ashed at high temperature, the ash is dissolved with hydrochloric acid and prepared into an aqueous solution, the absorbance of the standard solution and the sample solution is measured with an atomic absorption spectrometer, the concentration of the element to be measured in the sample solution is directly printed by the printer or found from the working curve, and then the magnesium content in the sample is calculated.

4. Reagents and materials (purity / preparation)

• 4.2 Materials
  • a. Air: filtered compressed air, pressure not less than 350 kPa;
  • b. Acetylene gas: in steel cylinders;
  • c. Quantitative filter paper: diameter 9 cm.
• 5 Reagents
  • 5.1 Unless otherwise specified, the reagents used in this standard are all analytical grade reagents. Water shall meet grade three in GB/T 6682.
  • 5.2 Metallic magnesium.
  • 5.3 Strontium nitrate: prepare a 30 g/L strontium nitrate solution. (The source text source-text extraction has "nitrate [garbled cation name]", "nitrate [garbled cation name]", "silver nitrate [source name conflicts with context]"; according to the context it should be strontium nitrate, requires confirmation against the source standard (source-text extraction))
  • 5.4 Hydrochloric acid: prepare 1:1 (volume ratio) and 1% (m/m) hydrochloric acid solutions.
• 6 Preparatory work
  • 6.1 Zeroing blank solution: add 20 mL 1:1 hydrochloric acid solution and 10 mL 30 g/L strontium nitrate solution to a 1 L volumetric flask, and dilute to the mark with water.
  • 6.2 Magnesium stock solution: accurately weigh 0.5000 g metallic magnesium into a 50 mL beaker, after completely dissolving with 1:1 hydrochloric acid solution, quantitatively transfer to a 500 mL volumetric flask, and dilute to the mark with 1% (m/m) hydrochloric acid solution. The concentration of this stock solution is 1000 μg/mL. (The source text source-text extraction has "IOOOpgmg/ML"; according to the context it should be 1000 μg/mL, requires confirmation against the source standard (source-text extraction))
  • 6.3 Magnesium standard working solution: use a pipette to respectively transfer 0.5, 1.0, 1.5, 2.0, 2.5 mL of the above stock solution into 5 100 mL volumetric flasks, and add to each volumetric flask 2 mL 1:1 hydrochloric acid solution, 10 mL 30 g/L strontium nitrate solution, dilute to the mark with water, mix well and set aside. The concentrations of the prepared magnesium standard working solutions are respectively 5.0, 10.0, 15.0, 20.0, 25.0 μg/mL. (The source text source-text extraction has "25.[unreadable digit]c gmg/-L"; according to the context it should be 25.0 μg/mL, requires confirmation against the source standard (source-text extraction))

5. Instruments and equipment

• a. Atomic absorption spectrophotometer: equipped with a 10 cm single-slot air-acetylene burner head, magnesium hollow cathode lamp;
• b. High-temperature furnace: capable of heating to 1000 ℃;
• c. Porcelain crucible: 30 mL;
• d. Volumetric flasks: 100, 500 mL, 1 L;
• e. Pipettes: 5 mL;
• f. Balance: sensitivity 0.01 mg.

6. Recommended operating conditions

Typical instrument conditions (listed in the source text):

• Wavelength: 285.2 nm
• Spectral bandwidth: 0.7 nm (the source text source-text extraction has "0. 7", requires confirmation against the source standard (source-text extraction))
• Lamp current: 1 (the unit in the source text source-text extraction is "[unreadable unit]", suspected to be mA, requires confirmation against the source standard (source-text extraction))
• Integration time: 0 (the unit in the source text source-text extraction is "5", suspected to be s, requires confirmation against the source standard (source-text extraction))
• Air flow rate: 25 (the unit in the source text source-text extraction is "Vmm", suspected to be L/min, requires confirmation against the source standard (source-text extraction))
• Acetylene flow rate: 2.5 (the unit in the source text source-text extraction is "Lmi n", suspected to be L/min, requires confirmation against the source standard (source-text extraction))
• Working mode: concentration printing
• Burner head rotation angle: 30 (the unit in the source text source-text extraction is "(0)", suspected to be °, requires confirmation against the source standard (source-text extraction))

Source note: Adjust the instrument according to the conditions listed in the table below, ignite the flame and burn for 5 min to preheat the burner head (for different instrument models, the conditions listed in the table below may vary).

7. Sampling and sample preparation

• 7.1 Weigh an additive sample equivalent to about 1 mg of magnesium into a 30 mL crucible (weighed to 0.01 mg).
• 7.2 Fold and cut open a piece of quantitative filter paper, roll it into a conical ignition wick, stand the ignition wick stably in the crucible containing the weighed sample, covering the sample surface.
• 7.3 Place the crucible containing the sample and ignition wick on an electric furnace and slowly heat until smoking, ignite the ignition wick, and burn off the combustible matter.
• 7.4 Move the crucible containing the sample residue into a high-temperature furnace heated to 800 ℃±20 ℃ and ash for 20 min, take out the crucible and cool to room temperature, moisten the ash with a small amount of water, add 2 mL 1:1 hydrochloric acid solution to dissolve the ash.
• 7.5 Quantitatively transfer the sample solution to a 100 mL volumetric flask, add 10 mL 30 g/L strontium nitrate solution, dilute to the mark with water, shake well and set aside for measurement.

8. Analysis procedure

• 7.6 Adjust the instrument according to the conditions listed in Section 6, ignite the flame and burn for 5 min to preheat the burner head.
• 7.7 Establish the standard working curve: zero with the zeroing solution, aspirate the magnesium standard working solution, and the instrument will automatically establish the standard working curve for determining magnesium content in additives (when using a recorder, manually draw the working curve for determining magnesium content in additives based on the absorbance of the standard series).
• 7.8 Determine the sample: aspirate the sample solution, and the printer will directly print the concentration of the sample solution (when using a recorder, find the concentration of the sample solution from the working curve based on the absorbance of the sample solution).

9. Qualitative and quantitative determination and calculation formula

The magnesium content in the sample X〔% (m/m)〕is calculated according to the following formula:

X = (c × 100) / (m × 1000) × 100 = c / (10 × m)

Where:

• c — magnesium concentration in the sample solution, μg/mL;
• m — sample amount, g.

(The formula layout in the source text source-text extraction is chaotic; organized according to the context, requires confirmation against the source standard (source-text extraction))

10. Precision

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

9.1 Repeatability: the difference between two results obtained by repeated determination by the same operator shall not exceed the following values.

9.2 Reproducibility: the difference between two determination results respectively proposed by different laboratories shall not exceed the following values.

11. Report

Take the arithmetic mean of two results of repeated determination as the determination result, and retain the data to two decimal places.

12. Referenced documents

• GB/T 6682 Water specifications and test methods for analytical laboratory use.

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 for questions and answers