Rubber — Determination of metal content by atomic absorption spectrometry — Part 4: Determination of manganese content
1Key Takeaways
This document specifies an atomic absorption spectrometric method for the determination of the manganese content of rubbers. The method is applicable to raw rubber and rubber products having manganese content above 0,5 ppm. Manganese contents below this limit can be determined, provided that suitable adjustments are ma…
2Expert Interpretation
An in-depth interpretation of ISO 6101-4:2022 Atomic absorption spectrometric determination of manganese content in rubber, covering key technical points such as method principles, reagent configuration, instrument requirements, calibration steps and result calculation. It is suitable for the accurate detection of manganese content ≥0.5ppm in natural rubber and rubber products.
Analysis of the core content of the standard
ISO 6101-4:2022 specifies the standard method for determining the manganese content in rubber materials by atomic absorption spectrometry, which is applicable to raw materials and products with a manganese content of ≥0.5ppm. The standard uses an atomic absorption spectrometer at a wavelength of 279.5nm for measurement, and the detection limit can be further reduced by the standard addition method.
Method principle and technical evolution
The main technical changes of the 2022 version include:
| Change items | 2014 version | 2022 version |
|---|---|---|
| Ashing temperature | Unspecified carbon black product temperature | Added 950±25℃ carbon black product ashing conditions |
| Hydrochloric acid concentration | Unlimited | Uniformly adjusted to 2% to prevent burner pollution |
| Nitric acid preparation | 11.5cm³ concentrated nitric acid | corrected to 16cm³ to eliminate calculation errors |
Key operation process
1. Sample pretreatment
Select ashing conditions according to the material type:
- Natural rubber: 550±25℃
- Products containing carbon black: 950±25℃
Note:After ashing, the ash needs to be moistened with deionized water and then added with acid solution to dissolve. Avoid using a glass rod to stir and cause ash loss.
2. Preparation of standard solution
Use gradient dilution method to establish calibration curve:
| Volume of standard solution (cm³) | Manganese content (μg/cm³) |
|---|---|
| 25.0 | 2.5 |
| 10.0 | 1.0 |
| 5.0 | 0.5 |
Implementation suggestions
Key points of quality control
- A blank test must be carried out simultaneously with each batch of tests
- Use Platinum crucible for handling silicate samples
- Calibration solution must be prepared on the same day
- Repeat measurement deviation should be ≤0.02μg/cm³ (95% confidence level)
Special sample handling
For samples with manganese content <0.5ppm, it is recommended to:
- Increase the sampling volume to 10g
- Use graphite furnace atomization technology
- Apply the standard addition method (see standard Appendix A for details)
Result calculation and report
Manganese content calculation formula:
ω(Mn) = [ρ(Mn)t - ρ(Mn)b] × f / (200×m)
Where f is the dilution factor, it is reported as a percentage when the concentration is ≥0.1%, otherwise it is expressed in mg/kg.