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D2085-89 – Standard Test Method Technical Guide
🧪 Overview and Significance
This standard, ASTM D2085-89, specifies the lime ignition method for determining chloride in pentachlorophenol (PCP) treating solutions and treated wood. This chloride measurement is used to calculate PCP concentration. The method is applicable for up to 0.05 g of PCP in treating solutions (Section 8), up to 0.05 g in wood volumes up to 0.25 in.³ (Section 9), and up to 0.25 g in wood volumes up to 2.0 in.³ (Section 11).
The method is not suitable for samples containing halogens other than chlorine unless appropriate corrections are applied. Total halogen, excluding fluorine, is expressed as its pentachlorophenol equivalent of chloride.
🔬 Apparatus and Reagents
Essential apparatus includes crucibles (iron, nickel, or porcelain), a Meker-type burner or electric muffle, an analytical balance sensitive to 0.001 g, a magnetic stirrer, a Büchner funnel, suction flask, vacuum source, and a food blender with a half-pint jar. All reagents must be of reagent grade, and water must conform to ASTM D1193 specifications.
| 🟦 Sample Type | 📐 Maximum PCP Content | 📏 Volume/Amount |
|---|---|---|
| Treating Solutions | 0.05 g | Up to 0.05 g |
| Wood (Small Volume) | 0.05 g | Up to 0.25 in.³ |
| Wood (Large Volume) | 0.25 g | Up to 2.0 in.³ |
| 🔬 Reagent | 📏 Concentration | ⚙️ Preparation |
|---|---|---|
| Ammonium Thiocyanate | Approximately 0.1 N | Dissolve 7.6 g of NH₄CNS in water |
📝 Test Procedure and Methodology
The procedure involves adding excess silver nitrate to a nitric acid solution containing the chloride. The silver chloride is filtered off, and the excess silver is titrated with ammonium thiocyanate in the presence of a ferric salt indicator. The endpoint is detected by a pinkish-brown color due to excess ferric thiocyanate.
This method ensures accurate chloride determination for calculating pentachlorophenol content in the sample.
⚠️ Safety Notice: The standard does not address all safety concerns. Users must establish appropriate safety and health practices and comply with regulatory limitations before conducting tests.
💡 Technical Tip: For consistent results, ensure that the titration is performed with a magnetic stirrer to achieve thorough mixing. The endpoint color change is sharp and should be observed under consistent lighting conditions.
❓ Frequently Asked Questions
🔍 What is the maximum pentachlorophenol content determinable in treating solutions?
Up to 0.05 g of pentachlorophenol in treating solutions per Section 8 of the standard.
💡 Can this method be used for samples with halogens other than chlorine?
No, unless appropriate corrections are made. The method is specifically for chlorine-based halogens.
⚡ What indicates the endpoint in the titration?
The endpoint is indicated by the formation of a pinkish-brown color from excess ferric thiocyanate.
📌 What type of water is specified for reagent preparation?
Reagent water conforming to ASTM Specification D1193.