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D6069-01 – Standard Test Method Technical Guide
🧪 Scope and Application
This test method is specified for the determination of total nitrogen (both organic and inorganic) in aromatic hydrocarbons, their derivatives, and related chemicals. It is applicable for nitrogen concentrations in the range of 0.3 to 2 mgN/kg, where the detector response is linear. For higher nitrogen concentrations, Test Method D4629 should be used.
All test results must be rounded to the nearest unit in the last right-hand digit as per Practice E29. The values stated in SI units are regarded as standard, with inch-pound units provided for information only.
⚙️ Test Procedure and Principle
A specimen is introduced into a gas stream at a controlled rate and carried into a high-temperature furnace operating at >900°C with excess oxygen. This oxidative pyrolysis converts organic and inorganic nitrogen to nitric oxide (NO). The NO then reacts with ozone in a detector at reduced pressure (<760 mm Hg) to produce excited nitrogen dioxide molecules. As these molecules return to ground state, they emit light, which is detected by a photomultiplier tube. The signal is proportional to the nitrogen concentration, and the reduced pressure enhances sensitivity and reduces noise.
| 🟦 Technical Parameter | 📏 Requirement |
|---|---|
| Oxidation Furnace Temperature | >900°C |
| Detector Operating Pressure | <760 mm Hg |
| Applicable Nitrogen Concentration | 0.3 to 2 mg/kg |
| Pyrolysis Environment | Oxygen-rich |
💡 Tip: To maximize sensitivity, maintain the detector pressure strictly below 760 mm Hg and ensure furnace temperature exceeds 900°C for complete oxidative pyrolysis.
📊 Key Specifications and Compliance
This test method adheres to ASTM standards and includes references to Practice E29 for rounding, Test Method D4629 for higher concentrations, and Practice D3437 for sampling. Safety must be considered, with specific hazard statements referred to in Section 9 of the standard.
The precision of the method is established through interlaboratory studies as per Practice E691.
| 📐 Referenced Standard | 🎯 Purpose |
|---|---|
| D4629 | Trace Nitrogen in Liquid Petroleum Hydrocarbons (for >2 mg/kg) |
| E29 | Rounding-off Test Data for Compliance |
| E691 | Interlaboratory Precision Study |
⚠️ Warning: Always refer to Section 9 for specific hazard statements related to chemical handling. Use appropriate personal protective equipment and work in a well-ventilated area.
❓ Frequently Asked Questions
🔍 What is the applicable nitrogen range for this test method?
The method is applicable for nitrogen concentrations from 0.3 to 2 mg/kg in aromatic hydrocarbons.
💡 Why is reduced pressure used in the detector?
Reduced pressure (<760 mm Hg) lowers the probability of excited NO2 molecules colliding with other molecules, thus enhancing chemiluminescence sensitivity and reducing noise.
⚡ What safety considerations are highlighted?
Section 9 provides specific hazard statements. Users must establish safety and health practices and follow regulatory limitations.
📌 How should data be reported for compliance?
Data must be rounded to the nearest unit in the last right-hand digit as per Practice E29 to ensure conformance with specified limits.