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International Starch Institute
Science Park Aarhus, Denmark
ISI 05-2e Determination of Dry Matter in Oven at 105 oC
| 1. Scope | The method is applicable to starch, dextrose - anhydrous and monohydrate
- and total sugar.
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LT 15. Dec- 1964 Rev. LT 21. Nov. 1997 |
| 2. Principle | The sample is dried at 105 oC
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| 3. Apparatus | 3.1 Analytical balance weighing to the nearest 1 mg. 3.2 Dish of aluminium or glass with tight-fitting lid 3.3 Electrically heated oven. 3.4 Desiccator with dry drying agent
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| 4. Procedure | Dry dish (3.2) 1/2 hours in oven (3.3) at 105 oC. | |
| Cool dish in desiccator (3.4) to room temperature and weigh on balance (3.1) to nearest 1 mg. Weight = w0 | Cool 40 min | |
| Weigh 2 g of sample in dish to the nearest 1 mg. Weight = w1. | Take 5 g total sugar | |
| Dry dish and sample over night (min. 16 hours) in vacuum at 105 oC | With one dying step only time may be extended | |
| Close lid and cool in desiccator for 1 hour. Weigh immediately after
removal from desiccator to nearest 1 mg. Weight=w2
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Possibly re-heat to constant weight | |
| 5. Calculation | Dry matter (DM) in percent of sample (average results of two samples to
one decimal) = DM % = 100 x (w2 - w0) / (w1 - w0)
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| 6. Notes | Alternative method: Drying at 70 oC or 100 oC in
vacuum.
The European Pharmacopoeia 4 specifies for potato and wheat starch drying at 130 oC for 90 min and for maize and rice starch drying at 100-105 oC to constant weight. |
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| 7. Reference | International Standard: ISO 1741 |
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Keywords: laboratory method determination dry matter substance starch oven drying