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D2023-89 – Standard Test Method Technical Guide
The ASTM D2023-89 (Reapproved 2024) standard provides a test method for analyzing the apparent sodium toluene sulfonate (NaTS) content in detergents. This method relies on separation and ultraviolet absorption techniques, with specific apparatus and procedural requirements.
📐 Test Method Overview and Scope
This test method covers the analysis for the apparent sodium toluene sulfonate content of detergents. The values stated in SI units are regarded as standard. The method separates low molecular weight sulfonates from higher molecular weight sulfonates by extracting sulfonic acids in hydrochloric acid solution using ethyl ether as solvent. Determination is performed via ultraviolet absorption, with results based on standardization using p-toluene sulfonate.
This standard does not address all safety concerns; users must establish appropriate safety, health, and environmental practices. Material Safety Data Sheets should be reviewed for all reagents used.
⚙️ Apparatus and Reagents
Critical apparatus includes separatory funnels of 500 mL capacity, an analytical balance, and a spectrophotometer equipped for UV analysis between 230 nm and 300 nm. Absorption cells with quartz windows of 1.00 cm and 5.00 cm path lengths are required. All reagents must be reagent grade conforming to ACS specifications, with reagent water complying with ASTM D1193.
| 🟦 Apparatus | 📏 Specification |
|---|---|
| Separatory Funnels | 500 mL capacity, glass-stoppered, pear-shaped |
| Balance | Analytical |
| Spectrophotometer | UV range 230-300 nm with 1.00 cm and 5.00 cm quartz cells |
📊 Interferences and Technical Notes
Interferences include any low molecular weight substituted benzene sulfonate or benzene sulfonate itself, which will give an apparent toluene sulfonate figure. Since the method is standardized with p-toluene sulfonate, o-sulfonate will not be assayed correctly. When contamination is suspected, a complete absorption curve should be run for comparison with known samples.
Absolute cleanliness of apparatus is essential. Use only glass apparatus; contact with rubber, cork, or hands can introduce absorbance errors.
Tip: Ensure absolute cleanliness of all glass apparatus. Avoid contact with rubber, cork, or hands to prevent absorbance errors. Use quartz absorption cells for UV measurements.
Note: The method details are based on the use of the Beckman DU or Cary recording spectrophotometers. Equivalent spectrophotometers may be used, provided suitable modifications can be made in the details of the method.
❓ Frequently Asked Questions
🔍 What are the main interferences in the test?
Low molecular weight substituted benzene sulfonates and benzene sulfonate itself interfere, giving an apparent toluene sulfonate figure. The method is standardized with p-toluene sulfonate, so o-sulfonate is not assayed correctly.
💡 How is the test method summarized?
The test method separates low molecular weight sulfonates from higher molecular weight sulfonates by extracting sulfonic acids with ethyl ether in hydrochloric acid solution. The determination is done via ultraviolet absorption.
⚡ What apparatus is required for this test?
Key apparatus includes 500 mL separatory funnels, an analytical balance, and a spectrophotometer with UV accessories for 230-300 nm, using 1.00 cm and 5.00 cm quartz absorption cells.
📌 What is the scope of ASTM D2023-89?
The scope covers the analysis for apparent sodium toluene sulfonate content in detergents. Values are stated in SI units, and users are responsible for safety and regulatory compliance.