ASTM D500 Test Methods of Chemical Analysis of Sulfonated and Sulfated Oils
TOTAL DESULFATED FATTY MATTER (FOR SULFATED OILS)
29. Scope
29.1 This test method covers the determination of the total desulfated fatty matter in a sample of sulfated oil by decomposition with diluted mineral acids and extraction of the decomposed fat. This test method is not applicable to samples that are not completely decomposed upon boiling with mineral acids.
30. Reagents
30.1 Ethyl Ether.
30.2 Sulfuric Acid (1 + 19) - Carefully mix 1 volume of concentrated sulfuric acid (H2SO4, sp gr 1.84) into 19 volumes of water while stirring.
31. Procedure
31.1 The procedure consists of decomposing the sample with H2SO4, extracting the fatty matter with ether, evaporating the solvent, and weighing the residue. After cooling, transfer the titrated solution obtained after determining organically combined sulfuric anhydride in accordance with Test Method A or Test Method B (18.1.2 or 23.1.2) into a 250-mL separatory funnel and shake with 50 mL of ether. Draw off the water layer into another separatory funnel and extract twice with 25-mL portions of ether. Wash the combined ether layers with 15-mL portions of water until the wash water is neutral to methyl orange. Transfer the ether layer to a tared 150-mL beaker, evaporate on the water bath until practically free from solvent, dry in a hot-air oven at 105 to 110°C for 30 min, cool in a desiccator, and weigh. Repeat the heating for 30-min periods until constant weight is obtained.
NOTE 4 - Reserve the extracted fatty matter for the subsequent determination of unsaponifiable matter (Sections 37-41).
32. Calculation
32.1 Calculate the total desulfated fatty matter as follows:
Total desulfated fatty matter, % = (A/B) x 100
where:
A = weight of residue, g, and
B = weight of sample, g.
