ISI 15-1e Determination of Aldehyde Groups in Starch
ISI 15-1e Determination of Aldehyde Groups in Starch 1. Scope The method is applicable to oxidised starch 2. Principle Free sulphur dioxide is determined in a mixture of starch and sodiumbisulphite with and without an alkaline treatment. The difference is the aldehyde bound sulphur dioxide. LT 30 Nov 1964 Rev. LT 03 Sep 1999 3. Apparatus 3.1 Analytical balance weighing to the nearest 0.1 mg. 3.2 Conical flask 1000 ml 3.3 Burette 25 ml 4. Reagents 4.1 Sodium bisulphite: 4 g NaHSO 3 is dissolved in water. Make up to 1000 ml with water. 4.2 Sodium thiosulphate 0.1N 4.3 Iodine 0.1N 4.4 Hydrochloric acid 1 N 4.5 Sodium hydroxide 0.1 N 4.6 Sodium thiosulphate 0.02N: 20.0 ml (4.2) Sodium thiosulphate 0.1N diluted to 100 ml with distilled water. Keep one day only. 4.7 Iodine 0.02N: 20.0 ml (4.3) Iodine 0.1N diluted to 100 ml with distilled water. Keep one day only. 5. Procedure Weigh 15 g (w) sample to the nearest 0.1 mg in a 1000 ml conical flask Gelatinising Add 550 ml distilled w