ISI 21-1e Determination of Sand in Starch


 

1. Scope The method is applicable to native starch.

 

 LT 18. Dec. 1966
Rev. LT 11.Dec.1998
2. Principle Incineration of starch sample at 525 oC and determination of the residue insoluble in hydrochloric acid.

 
3. Reagents 3.1 Hydrochloric acid, 10% solution Pour and mix carefully - use eye protection
3.2 Silver nitrate solution

 
4. Apparatus 4.1 Analytical balance weighing to the nearest 0.1 mg.

4.2 Ashing dish of platinum

4.3 Electrically heated furnace.

4.4 Desiccator with dry drying agent

4.5 Bunsen burner

4.6 Filter funnel with ash free filter, 9 cm diameter

 
5. Procedure Careful clean the ashing dish (4.2) and calcinate it 1/2 hour in furnace (4.3) at 525 oC.
Cool dish in desiccator (4.4) to room temperature and weigh on balance (4.1) to nearest 0.1 mg. Weight = w0 Clean always new dish in boiling HCl (3.2) and rinse in water
Place 10 g of sample or an aliquot portion of a dissolved sample in ashing dish. Weigh on balance (4.1) to nearest 1 mg. Weight = w1
Incinerate sample to constant weight.
Mix incinerated sample with 10 ml hydrochloric acid solution (3.1) and heat to boiling for two minutes. Filter through ash-free filter (4.6) and wash with hot distilled water until the filtrate is negative in test of Cl- with silver nitrate (3.2)..
Incinerate the filter on a Bunsen burner (4.5) or equivalent until completely carbonised.
Finish incineration in the furnace (4.3) at 525 oC until residual carbon has disappeared.. Incinerate 2 hours
Cool in desiccator to room temperature. Weigh immediately after removal from desiccator to nearest 0.1 mg. Weight=w2

 
6. Calculation Sand in percent of sample as is (average two results to the second decimal) =

Sand % = 100 x (w2 - w0) / (w1 - w0)

 

 Correct eventually to dry basis

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