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D2989-01 – Standard Test Method Technical Guide
📐 Standard Scope and Method Overview
ASTM D2989‑01 (Reapproved 2022) specifies a test method for determining acidity or alkalinity in halogenated organic solvents and their admixtures. The standard covers acidity determination; alkalinity may be measured using Test Methods D2106 with an end point at pH 7 by bromothymol blue or pH meter. All values are stated in SI units, and safety precautions are detailed in Section 7.
According to the summary, a sample is first tested for pH per Test Method D2110. If the pH exceeds 7.0, alkalinity is determined via D2106. If the pH is below 7.0, free acid content is found either by Procedure A (water extraction with a glass‑electrode pH meter) or Procedure B (anhydrous methanolic sodium hydroxide titration). This approach allows the method to be used for manufacturing and purchasing specifications as well as for monitoring solvents in service.
⚙️ Apparatus and Reagent Specifications
The standard requires precise equipment and reagent‑grade chemicals to ensure repeatable results:
| ⚙️ Equipment | 📏 Specification |
|---|---|
| Separatory Funnel | 250 mL |
| Graduated Cylinder | 100 mL |
| Volumetric Pipets | 1, 10, 25, 50 mL |
| Beaker | 100 mL |
| Borosilicate or Stainless Steel Beaker | 2 L |
| Erlenmeyer Flask | 100 mL |
| pH Meter with pH Electrodes | Standard |
| Buret | 10 mL |
| Volumetric Flasks | 100 mL, 1 L |
| Micro Buret (Class A) or Syringe | 5 mL or 100 µL |
All reagents must conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, unless otherwise noted. This maintains the purity needed for accurate free‑acid or alkalinity measurements.
📊 Procedures and Interpretation
When pH is below 7.0:
- Procedure A uses water extraction followed by titration with a glass‑electrode pH meter.
- Procedure B is an anhydrous methanolic sodium hydroxide titration for direct determination.
Tip: Extract with purified, CO₂‑free water to avoid introducing acidic or basic interferents.
Safety: Halogenated solvents can be toxic and flammable. Work in a fume hood and consult Section 7 for complete precautions.
❓ Frequently Asked Questions
🔍 What does D2989‑01 cover?
It covers acidity determination in halogenated organic solvents and admixtures; alkalinity can be determined via Test Methods D2106.
💡 How do I choose between Procedure A and Procedure B?
Use Procedure A when water extraction is feasible; use Procedure B (anhydrous titration) when the sample is water‑sensitive or direct titration is preferred.
⚡ Which equipment is essential?
A 250 mL separatory funnel, 100 mL graduated cylinder, pH meter, and Class‑A micro buret (or 100 µL syringe) are mandatory.
📌 Why is this test method used in industry?
It provides a standard basis for manufacturing and purchasing specifications and helps monitor solvent degradation during use.