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D4947-05 – Standard Test Method Technical Guide
ASTM D4947-05 provides a standardized test method for determining residues of chlordane and heptachlor in indoor air, utilizing polyurethane foam (PUF) sampling coupled with gas chromatography and electron capture detection (GC-ECD).
🧪 Scope and Applicability
This test method covers the sampling and analysis of indoor atmospheres for residues of chlordane and heptachlor. It is applicable to concentration ranges of 0.1 to 100 µg/m³ for chlordane and 0.01 to 80.0 µg/m³ for heptachlor, based on sampling volumes of at least 0.25 m³. The method accounts for the technical-grade mixture of chlordane, which consists of over 50 compounds including α- and γ-chlordane, heptachlor, and trans-nonachlor.
⚠️ User Safety Responsibility: As stated in Section 1.4, this standard does not address all safety concerns. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
⚙️ Summary of Sampling and Analytical Procedure
A low-volume sampler (1 to 5 L/min) is employed to collect airborne residues on a sorbent cartridge containing PUF. The analytes are then extracted from the cartridge using a solution of 5% diethyl ether in hexane. Analysis is performed by gas chromatography (GC) equipped with an electron capture detector (ECD).
Due to the high potential for interfering materials with similar retention times, the standard mandates confirmatory analysis. This is achieved through column chromatography on a different stationary phase or the use of a secondary chromatographic column of a different type to ensure accurate identification and quantification.
📊 Key Technical Parameters
| 🟦 Parameter | 📏 Specification | 🎯 Details |
|---|---|---|
| Analyte 1 | Chlordane (Technical Mixture) | Concentration range: 0.1 – 100 µg/m³. Major components include α/γ-chlordane, heptachlor, and trans-nonachlor. |
| Analyte 2 | Heptachlor | Concentration range: 0.01 – 80.0 µg/m³. May be used alone or in formulations with technical chlordane. |
| Sampling Device | Low-volume PUF Sampler | Flow rate of 1 to 5 L/min. Minimum sampled air volume is 0.25 m³. |
| Extraction Solvent | 5% Diethyl Ether in Hexane | Used to recover target analytes from the PUF sorbent cartridge prior to GC-ECD analysis. |
| Detection Limits | Variable | Dependent upon specific GC conditions and the total length of the sampling period. |
💡 Interference Confirmation: The standard (Section 4.3) strongly advises that positive identification of chlordane and heptachlor must be supported by column chromatography on a different stationary phase or a second GC column of a different type to resolve co-eluting compounds.
❓ Frequently Asked Questions
🔍 What does “technical chlordane” refer to in this standard?
Technical chlordane is a complex mixture of chlorinated Diels-Alder adducts comprising 50 or more compounds, including α- and γ-chlordane, heptachlor, and trans-nonachlor.
💡 What is the recommended sampling flow rate for this test method?
The standard specifies the use of a low-volume sampler with a flow rate of 1 to 5 L/min to collect airborne residues onto the PUF sorbent cartridge.
⚡ How are potential interferences handled during analysis?
To mitigate interferences, the standard requires confirmatory analysis via column chromatography or by utilizing a second GC column of a different type to resolve co-eluting compounds.
📌 What is the required minimum air volume for sampling?
The test method is applicable to sampling periods designed to collect at least 0.25 m³ of air to ensure adequate sensitivity for the defined concentration ranges.