Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D3973-85 – Standard Test Method Technical Guide
🧪 Scope and Applications
ASTM D3973-85 describes a test method for analyzing low-molecular weight halogenated hydrocarbons in water, primarily drinking water, but it is also suitable for environmental and waste waters with proper validation. This method covers halomethanes, haloethanes, and related extractable organohalides, with trihalomethanes detectable from 1 µg/L to 200 µg/L. Detection limits vary based on the compound, sample matrix, and gas chromatographic system performance.
⚠️ For compounds not listed in the precision and bias section, users must validate the method by collecting relevant precision and bias data from actual samples.
⚙️ Test Procedure and Extraction Method
The test method utilizes liquid/liquid extraction to isolate and concentrate the target compounds. A 5 mL aqueous sample is extracted once with 1 mL of solvent, achieving a five-fold concentration factor. A 3 µL aliquot of the extract is then analyzed via gas chromatography with an electron-capture detector (ECD). Extraction efficiencies for trihalomethanes typically exceed 90%. To correct for extraction losses, calibration standards should be extracted and analyzed under identical conditions.
💡 Always extract calibration standards using the same procedure as samples to ensure accurate quantification and account for any loss during extraction.
📊 Key Performance Data and Detection
| 🔬 Parameter | 📐 Value/Description |
|---|---|
| Concentration Range (Trihalomethanes) | 1 µg/L to 200 µg/L |
| Sample Volume | 5 mL |
| Solvent Volume | 1 mL |
| Concentration Factor | 5-fold |
| Extraction Efficiency | >90% for trihalomethanes |
| Detector | Electron-Capture Detector (ECD) |
| Confirmation Method | GC/MS or halogen specific detectors at >50 µg/L |
Compound identities are confirmed by comparing retention times on gas chromatographic columns with different polarities. For concentrations above 50 µg/L, confirmation can be done using halogen-specific detectors or GC/MS. For purgeable compounds at levels as low as 1 µg/L, Test Method D3871 with GC/MS detection is recommended.
| 📚 Standard | 📝 Description |
|---|---|
| D1129 | Terminology Relating to Water |
| D1193 | Specification for Reagent Water |
| D3871 | Test Method for Purgeable Organic Compounds in Water Using Headspace Sampling |
| E355 | Practice for Gas Chromatography Terms and Relationships |
❓ Frequently Asked Questions
🔍 What is the applicable concentration range for trihalomethanes?
The standard specifies a range from 1 µg/L to 200 µg/L.
💡 How are sample compounds confirmed?
Confirmation is done by observing retention times on GC columns of different polarities. At concentrations above 50 µg/L, GC/MS or halogen specific detectors can be used.
⚡ What extraction method is used in this test?
Liquid/liquid extraction is employed, using 5 mL of sample and 1 mL of solvent for a five-fold concentration.
📌 What detector is utilized in the gas chromatograph?
The standard specifies an electron-capture detector (ECD).