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D3179-02 – Standard Test Method Technical Guide
🔬 Test Methods Overview and Scope
These test methods, designated ASTM D3179-02, provide standardized procedures for the determination of total nitrogen in samples of coal and coke. The analytical data obtained are typically reported as part of the ultimate analysis per Practice D3176 or as specifically requested. Two distinct methods are included:
– Test Method A: Kjeldahl-Gunning Macro Analysis (with an alternative technique), covered in Sections 9-16.
– Test Method B: Kjeldahl-Gunning Semi-Micro Determination, covered in Sections 17-23.
The methods involve converting nitrogen into ammonium salts through destructive digestion of the sample with a hot, catalyzed mixture of concentrated sulfuric acid and potassium sulfate. These salts are subsequently decomposed in a hot alkaline solution, from which ammonia is recovered by distillation and finally determined by alkalimetric or acidimetric titration. The values stated in SI units are regarded as the standard. The standard was originally published as D3179 – 73 and the last previous edition was D3179 – 89 (2002)e1, with an editorial correction to Table 1 title in June 2004.
⚙️ Analytical Procedures and Reagents
Both methods require strict adherence to reagent purity and procedural steps to ensure reproducible results. Key reagents include concentrated sulfuric acid, potassium sulfate, and catalysts for digestion. Reagent water must conform to ASTM Specification D1193. No significant interferences have been determined using these procedures, but rigorous adherence is necessary to obtain good reproducible results. The procedure involves digestion of the sample, distillation of ammonia, and titration. An alternative technique is included in Test Method A for flexibility.
📊 Significance and Data Reporting
Nitrogen results obtained by these test methods are required to fulfill the requirements of ultimate analysis per Practice D3176 and may be used to evaluate the potential formation of nitrogen oxides as a source of atmospheric pollution. Nitrogen data are also used in comparing coals and in research. When the oxygen content of coal is estimated by difference, a nitrogen determination is necessary. Results should be reported according to the request, and calculations can be converted to different bases using Practice D3180.
| 🔬 Test Method | 📐 Description | ⚙️ Application |
|---|---|---|
| Test Method A | Kjeldahl-Gunning Macro Analysis | For larger sample sizes; includes an alternative technique |
| Test Method B | Kjeldahl-Gunning Semi-Micro Determination | For smaller sample sizes; semi-micro scale |
| 📊 Application | 💡 Purpose |
|---|---|
| Ultimate Analysis | Required for complete coal and coke characterization |
| Environmental Assessment | Evaluate potential NOx formation from combustion |
| Research and Comparison | Use in coal comparisons and estimation of oxygen content by difference |
Tip: Ensure all reagents meet specified purity requirements and that the digestion and distillation steps are followed meticulously to achieve optimal accuracy and reproducibility.
Warning: While no significant interferences have been identified, strict adherence to the standard procedure is critical to avoid variability in results. Safety practices should be established considering the use of hot concentrated acids.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D3179-02?
It covers the determination of total nitrogen in coal and coke using two methods: the Kjeldahl-Gunning macro analysis (Test Method A) and semi-micro determination (Test Method B).
💡 How is nitrogen converted in these methods?
Nitrogen is converted into ammonium salts by digestion with a hot, catalyzed mixture of concentrated sulfuric acid and potassium sulfate, then liberated as ammonia by alkaline distillation and quantified by titration.
⚡ What are the two test methods included?
Test Method A (Kjeldahl-Gunning Macro Analysis) is covered in Sections 9-16, and Test Method B (Kjeldahl-Gunning Semi-Micro Determination) is covered in Sections 17-23.
📌 Why is nitrogen analysis important for coal and coke?
It is necessary for ultimate analysis, helps evaluate potential NOx emissions, and is used in coal research, comparisons, and estimation of oxygen content by difference.