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D3695-95 – Standard Test Method Technical Guide
📐 Scope, Matrices, and Method Suitability
This test method (Designation D3695-95 (2021)) specifically covers the quantitative determination of a wide range of volatile alcohols with various structures and boiling points in water and wastewater. It utilizes direct aqueous-injection gas-liquid chromatography and achieves a minimum detection limit of approximately 1 mg/L.
The method has been validated for reagent grade Type II water (as defined in Specification D1193) and natural chlorinated tap waters. It is expressly the responsibility of the user to ensure the validity of the test method for untested matrices, such as industrial process streams. It is critical to note that organic acids, amines, and high-boiling, highly polar compounds are not readily detectable under these conditions. For compounds with similar functionalities, users are directed to other ASTM methods in Volumes 11.01 and 11.02.
⚙️ Analytical Procedure and Detection
As summarized in Clause 4 of the standard, a small aliquot of the aqueous sample is directly injected into a gas chromatograph using a microlitre syringe. The organic compounds are separated on a chromatographic column and eluted into a Flame Ionization Detector (FID) for quantification.
Identification of specific analytes is achieved by measuring the relative retention time or calculating the Kovats Index. Quantification is performed through direct comparison of the sample peak response with the response of a corresponding known standard. The standard strongly mandates that all procedures and critical precautions outlined in Practice D2908 for measuring volatile organic matter in water must be strictly followed during analysis.
📊 Specifications and Reference Documents
The following tables outline the key analytical specifications and compound applicability as derived from the standard text. The method relies on a robust framework of referenced ASTM standards to ensure consistency and reliability.
| 🟦 Parameter | 📏 Specification / Value |
|---|---|
| Minimum Detection Limit | ~ 1 mg/L |
| Injection Technique | Direct Aqueous-Injection (Microlitre Syringe) |
| Detector Type | Flame Ionization Detector (FID) |
| Compound Identification | Relative Retention Time / Kovats Index |
| Governing Practice | Practice D2908 |
| Unit System | SI Units |
| 📐 Compound Group | 🎯 Analytical Capability |
|---|---|
| Volatile Alcohols (wide range) | Quantitative Detection |
| Other Volatile Organic Compounds | Qualitative Detection |
| Organic Acids, Amines, High-Boiling Polar Compounds | Not Readily Detectable |
💡 Pro Tip: Strict adherence to the syringe technique and water purity guidelines found in Practice D2908 and Specification D1193 is essential for achieving the stated detection limits and minimizing carryover or contamination in the analysis.
⚠️ Important Consideration: The standard explicitly states that it is the user’s responsibility to establish appropriate safety, health, and environmental practices. Furthermore, the validity of the test method must be assured by the user for any matrices that are not explicitly covered (e.g., reagent Type II water and natural chlorinated tap waters).
❓ Frequently Asked Questions
🔍 What is the minimum detection limit for volatile alcohols using this method?
The minimum detection limit specified in the standard is approximately 1 mg/L for target alcohols in water.
💡 What type of detector and injection technique are specified?
The method specifically uses a Flame Ionization Detector (FID) and relies on direct aqueous injection of the sample into the gas chromatograph using a microlitre syringe.
⚡ Are organic acids and amines detectable under these conditions?
No. The standard clearly notes that organic acids, amines, and high-boiling, highly polar compounds are not readily detectable under the specified conditions of this test method.
📌 Which standard reference must be followed for the required procedures and precautions?
Practitioners must strictly follow the procedures and precautions detailed in Practice D2908, “Practice for Measuring Volatile Organic Matter in Water by Aqueous-Injection Gas Chromatography.”