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D1607-91 – Standard Test Method Technical Guide
🧪 Principle and Scope of the Test Method
ASTM D1607-91 (Reapproved 2018)´1, Standard Test Method for Nitrogen Dioxide Content of the Atmosphere (Griess-Saltzman Reaction), specifies a manual procedure for determining NO₂ concentrations. The method is validated for atmospheric concentrations from 4 µg/m³ to 10,000 µg/m³ (0.002 to 5 ppm(v)) when sampling is conducted using a fritted-tip bubbler. The analysis relies on the absorption of NO₂ in an azo-dye-forming reagent. A red-violet color develops within 15 minutes, and its absorbance is measured spectrophotometrically at 550 nm. This standard was developed under the jurisdiction of ASTM Committee D22 and adheres to the standardization principles of the WTO TBT Committee.
| 🟦 Parameter | 📏 Specification / Value | ⚡ Condition / Unit |
|---|---|---|
| Analyte | Nitrogen Dioxide (NO₂) | Atmospheric Gas |
| Detection Range | 4 to 10,000 | µg/m³ (0.002 to 5 ppm(v)) |
| Sampling Device | Fritted-tip bubbler | Gas absorption train |
| Maximum Sampling Period | 60 | Minutes |
| Flow Rate | 0.4 | Liters per minute |
| Color Development Time | 15 | Minutes |
| Measurement Wavelength | 550 | nm (red-violet absorption peak) |
💡 Technical Note: If your sample concentration exceeds 10 mg/m³ (5 ppm(v)) or contains high sulfur dioxide (SO₂) content, ASTM D1607 is not suitable. Refer directly to Test Method D1608 (Phenol-Disulfonic Acid Procedure) for accurate results in industrial atmospheres, gas burner stacks, or automotive exhaust.
⚙️ Apparatus, Reagents, and Sampling Guidelines
The sampling train must include a fritted-tip bubbler connected to a rotameter (calibrated per Practice D3195 or D3609) and a vacuum source. Reagent water must meet the purity standards of Specification D1193. The air sample is drawn through the bubbler containing the absorbing reagent for a maximum of 60 minutes at a precisely controlled flow rate of 0.4 L/min. Following sampling, the solution is allowed to stand for 15 minutes to ensure full color development before spectrophotometric analysis.
📊 Interferences and Alternative Methods
The standard explicitly warns