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D4128-18 – Standard Test Method Technical Guide
🔬 Scope and Application
This guide covers the identification and quantitation of organic compounds in water by combined gas chromatography and electron impact mass spectrometry (GC-MS). It is intended for volatile and semi-volatile organics that can be passed through a gas chromatograph without alteration, provided reference spectra are available and compounds are separable by GC. The guide is written for automated data acquisition and handling. Detection limits vary with matrix complexity, GC-MS system condition, sample preparation, and cleanup techniques. Lower detection levels can be achieved with modern instruments or selected ion monitoring (SIM). Interlaboratory detection and quantitation estimates should adhere to Practices D6091 and D6512. The guide is applicable to natural and treated waters and includes all modes of sample introduction.
⚙️ Methodology and Procedures
The guide supports multiple sample introduction modes, including injection of organic extracts, direct aqueous injection, and purge and trap techniques. It is applicable to capillary column gas chromatography. All values are stated in SI units. Users must establish appropriate safety, health, and environmental practices. The guide can be used for tentatively identifying organic constituents in natural and treated waters. Guidelines for quantitation are included from ASTM Test Methods D3871, D3973, and other GC-MS procedures. Actual detection limits must be determined in each laboratory based on specific conditions.
📊 Key Standards and References
The following table summarizes key ASTM standards referenced in this guide for sampling and analysis:
| 📏 Standard | 📐 Description |
|---|---|
| D3871 | Test Method for Purgeable Organic Compounds in Water Using Headspace Sampling |
| D3973 | Test Method for Low-Molecular Weight Halogenated Hydrocarbons in Water |
| D6091 | Practice for Determination of Interlaboratory Detection Estimate (IDE) |
| D6512 | Practice for Interlaboratory Quantitation Estimate (IQE) |
| D3370 | Practices for Sampling Water from Flowing Process Streams |
| D3694 | Practices for Preparation of Sample Containers and Preservation of Organic Constituents |
These standards provide essential procedures for sample collection, preparation, and quantitation to ensure accuracy and consistency.
⚠️ Safety Advisory: This standard does not address all safety concerns. Users must determine regulatory limitations and implement appropriate safety, health, and environmental practices.
💡 Best Practice: For optimal sensitivity, maintain the GC-MS system regularly and use cleanup techniques for complex samples. SIM can enhance detection for target compounds. Refer to Practices D6091 and D6512 for quality control.
❓ Frequently Asked Questions
🔍 What is the scope of this guide?
It covers identification and quantitation of volatile and semi-volatile organic compounds in water using GC-MS with electron impact, restricted to compounds with reference spectra and GC separation.
💡 What sample introduction methods are included?
Methods include direct aqueous injection, organic extract injection, and purge and trap techniques for various water types.
⚡ How are detection limits determined?
Detection limits depend on matrix, system, and preparation. Use Practices D6091 and D6512 for interlaboratory estimates, and consider SIM for lower levels.
📌 Is this guide applicable to all water samples?
It applies to natural and treated waters, but performance varies with complexity. Cleanup techniques may be necessary.