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D5560-95 – Standard Test Method Technical Guide
🧪 Scope and Significance of D5560-95
This standard, designated ASTM D5560-95 (Reapproved 2018), is specifically developed under Committee D31 on Leather and Subcommittee D31.08 on Fats and Oils. It provides a standardized test method for determining the neutral fatty matter in fats and oils, covering all degraded glycerides that behave as neutral fats. It is important to note that this procedure does not necessarily capture every mono and diglyceride present due to their water-soluble characteristics. All values are stated in SI units, and the method was developed in cooperation with the American Leather Chemists Association (ALCA).
| 🛠️ Apparatus / Reagent | 📝 Specification / Details |
|---|---|
| Erlenmeyer Flask | 125 mL capacity |
| Separatory Funnel | Standard separatory funnel for liquid-liquid extraction |
| Sodium Hydroxide (NaOH) | 0.5 N standard solution |
| Petroleum Ether | High purity extraction solvent |
| Phenolphthalein Indicator | Standard alcoholic solution for endpoint detection |
| Ethyl Alcohol | Denatured grade for sample dissolution |
⚙️ Test Procedure and Extraction Method
The analytical procedure functions on the principle of ether extraction of neutral materials. A 5 g sample is weighed into a 125 mL assay flask and dissolved in 50 mL of warmed denatured ethyl alcohol. The solution is titrated with 0.5 N NaOH using phenolphthalein as an indicator. Following the endpoint, a precise excess of 1 mL of the NaOH titrant is added.
The neutral oily matter is then isolated via three successive extractions with 50 mL portions of petroleum ether in a separatory funnel. The combined ether extracts are washed with water until completely free from alkali. Finally, the ether is evaporated, and the residue is dried to a constant weight to determine the total neutral oily matter.
💡 Best Practice Tip
Ensure the sample is fully dissolved in the alcohol before titration. Thorough washing of the ether layer is critical to remove all alkali, as residual base will lead to an erroneously high weight for the neutral residue, compromising the accuracy of the final result.
Ensure the sample is fully dissolved in the alcohol before titration. Thorough washing of the ether layer is critical to remove all alkali, as residual base will lead to an erroneously high weight for the neutral residue, compromising the accuracy of the final result.
📊 Calculation and Precision Considerations
The total neutral oily matter is calculated utilizing the standard formula established in the method:
Total Neutral Oily Matter (%) = (Weight of Residue × 100) / Weight of Sample
To determine the pure Neutral Fatty Matter, the unsaponifiable nonvolatile matter (measured via Test Method D5553) must be subtracted from the total neutral oily matter. Regarding precision, this method was adopted from the ALCA; as the original interlaboratory data are no longer available, users should verify reproducibility using suitable reference materials for the intended application.
| ⚙️ Critical Parameter | 📐 Specified Value |
|---|---|
| Sample Weight | 5 g |
| Solvent Volume (Alcohol) | 50 mL |
| Titrant Concentration | 0.5 N NaOH |
| Excess Titrant Added | 1 mL |
| Extraction Solvent Volume | 50 mL Petroleum Ether |
| Number of Extractions | 3 |
| Indicator | Phenolphthalein |
⚠️ Method Limitation
This test method does not necessarily determine all mono and diglycerides that may be present in the sample due to their water-soluble characteristics. For complete lipid profiling, supplementary analytical techniques may be required.
This test method does not necessarily determine all mono and diglycerides that may be present in the sample due to their water-soluble characteristics. For complete lipid profiling, supplementary analytical techniques may be required.
❓ Frequently Asked Questions
🔍 What is the primary application of ASTM D5560?
This standard is specifically intended for use within the leather industry for determining the neutral fatty matter in fats and oils used in processing. It was developed in cooperation with the American Leather Chemists Association (ALCA).
💡 What causes the limitation regarding mono and diglycerides?
The method relies on ether extraction. Because some mono and diglycerides exhibit water-soluble characteristics, they can be lost during the solvent washing steps, leading to their underrepresentation in the final residue weight.
⚡ How is the final Neutral Fatty Matter result corrected?
The calculation is a two-step process. First, the total neutral oily matter (which includes unsaponifiables) is determined via ether extraction. Second, the unsaponifiable nonvolatile matter content, found using Test Method D5553, is subtracted to yield the accurate neutral fatty matter.
📌 What is the precision and bias level of this test method?
The precision and bias data from the original interlaboratory study are no longer available. The standard itself advises users to verify the reproducibility of this method for their specific application through the use of certified reference materials.