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D1627-94 – Standard Test Method Technical Guide
🔬 Test Methods and Scope
The ASTM D1627-94 standard outlines test methods for the chemical analysis of acid copper chromate, applicable to both solid and solution forms. These methods are essential for ensuring compliance with Specification D1624 for wood preservatives. The analytical procedures are organized into three main sections: copper (calculated as CuO) in sections 7-10, hexavalent chromium (calculated as CrO₃) in sections 11-13, and pH of solution in section 14.
| 🟦 Section | 📏 Analyte | 🎯 Method Summary |
|---|---|---|
| 7-10 | Copper (as CuO) | Sample reacted with HCl and KI, then titrated with standard Sodium Thiosulfate solution |
| 11-13 | Hexavalent Chromium (as CrO₃) | Sample treated with excess Ferrous Ammonium Sulfate, unreacted portion titrated with Potassium Dichromate |
| 14 | pH of Solution | Measured using a glass electrode in accordance with Test Method E70 |
⚠️ Safety Note: Users must establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use, as per Section 1.3.
🧪 Analytical Procedures
For copper determination, a measured sample is reacted with hydrochloric acid and potassium iodide to complex the copper ion, followed by titration with a standard solution of sodium thiosulfate. The copper content is calculated as CuO. Chromium analysis involves diluting a chemically treated sample and adding an excess of ferrous ammonium sulfate; the unreacted ferrous ammonium sulfate is then titrated with a standard solution of potassium dichromate to determine the consumed chromium, calculated as CrO₃. The pH of the solution is measured directly using a glass electrode.
These methods are substantially the same as those in the American Wood-Preservers’ Association Standard A2 for analysis of waterborne preservatives and fire-retardant formulations.
💡 Reagent Purity: Reagent grade chemicals conforming to ACS specifications are required. Other grades may be used if they do not reduce accuracy. Water must be reagent water per Specification D1193.
📋 Reagents and Sampling
Purity of reagents is critical; all chemicals should be reagent grade. Water must be reagent water per D1193. For sampling, water solutions must be mixed thoroughly to ensure uniformity. The standard references Test Methods D38 for sampling of wood preservatives prior to testing.
Related standards include D1035, D1326, D1628, and D1003, which cover other chemical analysis methods for wood preservatives.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D1627-94?
The standard provides test methods for the chemical analysis of solid acid copper chromate and solutions, including determination of copper, hexavalent chromium, and pH.
💡 How is copper determined in this standard?
Copper is determined by complexation with hydrochloric acid and potassium iodide, followed by titration with sodium thiosulfate, and reported as CuO.
⚡ What is the significance of the pH test?
The pH test is included to ensure the solution meets the requirements of Specification D1624 for wood preservative treatment.
📌 What are the referenced standards for sampling?
Test Methods D38 is referenced for sampling wood preservatives prior to testing.