BS IOS 685:2020 pdf free.Analysis of soaps – Determination of total alkali content and total fatty matter content.
BS IOS 685 Decomposition of the soap by a known volume of standard volumetric mineral acid solution, extraction and separation of the liberated fatty matter with light petroleum and determination of the total alkali content by titration of the excess of acid contained in the aqueous phase with a standard volumetric sodium hydroxide solution. After evaporation of the light petroleum from the extract, dissolution of the residue in ethanol and neutralization of the fatty acids with a standard volumetric potassium hydroxide solution. Evaporation of the ethanol and weighing of the soap formed to determine the total fatty matter content.Dissolve the test portion (8.2) in about 100 ml of hot water. Pour the solution into one of the separating funnels (6.2) or into the extraction cylinder (6.3) and wash the beaker with small quantities of water, adding the washings to the separating funnel or to the extraction cylinder. Add a few drops of the methyl orange solution (5.Z) and then, from a burette, add, while vigorously shaking the separating funnel or the extraction cylinder, an accurately measured known volume of the sulphuric acid solution (5.4) until there is an excess of about 10 ml. Cool the contents of the separating funnel or of the extraction cylinder to about 25 °C and add 100 ml of the light petroleum (5.2]. Insert
the stopper and gently invert the separating funnel or the extraction cylinder, while maintaining a hold on the stopper. Open the stopcock of the separating funnel or the stopper of the extraction cylinder gradually to release any pressure, then close, gently shake and again release the pressure. Repeat the shaking until the water phase is clearly separated from the organic phase (if the two-phase layer is not obvious, the emulsification can be broken by adding ethanol that does not exceed the volume of the water phase), and then allow to stand. BS IOS 685 pdf download.