ISO 685-1975 pdf download – Analysis of soaps – Determination of total alkali content and total fatty matter content.
5 REAGENTS During the analysis, use only reagents of recognized analytical reagent grade and only distilled water or water of equivalent purity. 5.1 Acetone. 5.2 Light petroleum, boiling range between 46 and 60 “C. 5.3 Ethanol, 95 % (V/V) solution, neutralized to the phenolphthalein solution (5.8). 5.4 Sulphuric acid or hydrochloric acid, approximately 1 N standard volumetric solution 5.5 Sodium hydroxide, approximately 1 N standard volumetric solution, standardized using the methyl orange solution (5.7) as indicator. 5.6 Potassium hydroxide, approximately 1 N standard volumetric solution in ethanol (5.3). 5.7 Methyl orange, 2 g/l solution. 5.8 Phenolphthalein, 10 g/l solution in ethanol (5.3). .~ ~,. 6 APPARATUS Ordinary laboratory apparatus and 6.1 Beaker, capacity 250 ml, squat form, complying with IS0 3819.
7 SAMPLING The laboratory sample of soap shall be prepared and stored in accordance with the instructions given in IS0 . 8 PROCEDURE Carry out two determinations on the same sample. 8.1 Test portion Weigh, to the nearest 0,001 g, about 5 g of the laboratory sample into the beaker (6.1). 8.2 Determination Dissolve the test portion (8.1) 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 (5.7) 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 or hydrochloric acid solution (5.4) until there is an excess of about 5 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, whilst maintaining a hold on the stopper. Open the stop- cock 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 aqueous layer has become clear, and then allow to stand.