ISI 10-2e Determination of Carboxyl Groups in Starch
ISI 10-2e Determination of Carboxyl Groups in Starch 1. Scope The method is applicable to oxidised starch LT 18. Dec. 1964 Rev. LT 15. marts 1998 2. Principle Carboxyl groups are titrated by the Paste Titration Method 3. Apparatus 3.1 Analytical balance weighing to the nearest 0.1 mg. 3.2 Shaking boiling water bath. 3.3 Büchner funnel 55 mm 4. Reagents 4.1 Hydrochloric acid 0.1 N 4.2 Sodium hydroxide 0.1 N 4.3 Phenolphthalein: 1 g in 1 litre ethanol 90% 4.4 Silver nitrate, 0.1% 5. Procedure Weigh 5 g (w) sample to the nearest 0.1 mg in a 100 ml beaker Conversion Add 25 ml hydrochloric acid (4.1) and stir for 1/2 hour. Use magnetic stirrer Washing Filter on filter (3.3) or glass crucible. Flush beaker and filter with water until filtrate is free of chloride - test with silver nitrate (4.4) Increase hydrolysis parameters if flux too low Gelatinising Slurry filter cake with 300 ml distilled water in beaker. Place beaker in boiling water bath (3.2) for 15 min. Stir Titration Titra