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D1568-05 – Standard Test Method Technical Guide
🧪 Scope and Referenced Documents
Standard D1568‑05 (Reapproved 2014) covers the sampling and chemical analysis of alkylbenzene sulfonates in paste, powder, or liquid detergent form. These test methods ensure consistency in evaluating surfactant composition and purity. Key referenced documents include ASTM D1172 (Guide for pH of Aqueous Solutions of Soaps and Detergents) and ASTM D1193 (Specification for Reagent Water), which establish the baseline conditions for the analytical procedures.
📦 Sampling Procedures for Powders, Flakes, Liquids, and Pastes
The standard provides explicit guidelines in Sections 3 through 7 for obtaining representative samples. Section 3 grants the seller the right to be represented during sampling and to receive a duplicate sample. Specific protocols distinguish bulk powders from those packed in cans or cartons.
| 🟦 Parameter | 📏 Cans / Cartons (Section 4) | 📐 Bulk Powders / Flakes (Section 5) |
|---|---|---|
| Minimum Package Weight | 50 lb (22.7 kg) | 100 lb (45.4 kg) |
| Sampling Frequency | 1% of seller’s containers | 1% of seller’s containers |
| Minimum Gross Sample | 3 cans/cartons | 3 grab samples (0.5 lb / 227 g each) |
| Maximum Gross Sample | 20 lb (9.1 kg) | 20 lb (9.1 kg) |
| Packaging Protocol | Wrapped in paraffined paper, sealed, weighed, placed in airtight container, kept cool. | Mixed rapidly, placed in airtight container, sealed, and marked. |
⚠️ Safety Note: Section 8 of D1568‑05 provides specific hazard statements for these test methods. It is the responsibility of the user to establish appropriate safety, health, and regulatory practices prior to use.
⚙️ Key Analytical Procedures
The analytical sections of D1568‑05 cover a comprehensive suite of tests to characterize alkylbenzene sulfonates. These include moisture determination, quantification of inorganic salts, and unsulfonated matter.
| 🟦 Analysis | 📐 Standard Sections | 🎯 Key Notes |
|---|---|---|
| Preparation of Sample | Section 9 | Homogenization before analysis. |
| Moisture (Distillation) | 11 – 14 | Direct azeotropic distillation method. |
| Moisture (Karl Fischer) | 15 – 20 | Alternative coulometric or volumetric method. |
| Total Matter Insoluble in Alcohol | 21 – 23 | Determines inorganic salts and filler content. |
| Neutral Oil | 24 – 27 | Quantifies unsulfonated organic matter. |
| Chlorides (as NaCl) | 28 – 31 | Measures sodium chloride content. |
| pH | Section 32 | Measured per Guide D1172. |
💡 Technical Insight: The “Total Matter Insoluble in Alcohol” test (Sections 21‑23) is a critical quality metric that separates the active organic surfactant from inorganic builders and fillers, directly impacting product formulation verification.
❓ Frequently Asked Questions
🔍 What is the maximum gross sample size for powders and flakes as specified in D1568?
The gross sample shall not exceed 20 lb (9.1 kg). If the initial sampling plan would yield more than this amount, the percentage of packages sampled is reduced so that the amount drawn does not exceed this limit.
💡 How should alkylbenzene sulfonate samples be stored before testing?
Samples must be kept cool until tested. For cans or cartons, they are wrapped in paraffined paper, sealed, and placed in an airtight container. Bulk powder samples are mixed and sealed in airtight containers.
⚡ What is the purpose of the “Neutral Oil” determination in Sections 24‑27?
This test quantifies the amount of unsulfonated organic matter remaining in the alkylbenzene sulfonate, which is an indicator of the efficiency of the sulfonation process.
📌 Which referenced ASTM standards are essential for performing D1568‑05?
The standard specifically references ASTM D1172 (Guide for pH) and ASTM D1193 (Specification for Reagent Water) to ensure consistency in the analytical methods.