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International Starch Institute
Science Park Aarhus, Denmark
ISI 04-1e Determination of Dry Matter in Starch Syrup in Vacuum Oven at 70 oC
|1. Scope||The method is applicable to starch hydrolysates, syrups and dextrose
|LT 15. Dec. 1964
Rev. LT 21. Nov. 1997
|2. Principle||The starch sample is dried in vacuum at 70 oC
|3. Reagent||3.1 Kieselguhr, acid washed and dried.
Wash kieselguhr on a Büchner funnel with water acidified with 1 ml concentrated hydrochloric acid per l until washings turns acid (litmus). Rinse with water until chloride can no longer be detected with silver nitrate, AgNO3. Dry over night at 105 oC. Store in tight container.
|4. Apparatus||4.1 Analytical balance weighing to the nearest 1 mg.
4.2 Dish of aluminium or glass with tight-fitting lid
4.3 Electrically heated vacuum oven.
4.4 Desiccator with dry drying agent
4.5 Small stirring rod of glass
4.6 Glass beaker 100 ml
4.7 Weighing pipette, Quickfit
|5. Procedure||Fill 30 g kieselguhr (3.1) into dish (4.2).|
|Dry dish, kieselguhr and a stirring rod (4.5) 5 hours in oven (4.3) at 70 oC and max 34 mbar.||Alternatively dry at 105 oC over night.|
|Cool dish in desiccator (4.4) to room temperature and weigh on balance (4.1). Weight = w0||Let cool 1 hour|
|Weigh 10 g of sample in beaker (4.6) to the nearest 1 mg. Weight = w1.||Use weighing pipette (4.7) if possible. Take equivalent to 4 g dry matter|
|Mix with equal amount of hot water. Stir (4.5) and transfer to dish with kieselguhr. Flush beaker with 3x5 ml hot water. Stir kieselguhr and sample.||A weighing pipette make dilution and flushing superfluous|
|Dry dish and stirring rod 5 hours in vacuum at 70 oC||With one dying step only time may be extended|
|Cool and crush kieselguhr with stirring rod.
Dry again 10 hours in vacuum at 70 oC.
|For certain purpose this step may be omitted.|
|Close lid and cool in desiccator for 1 hour. Weigh immediately after
removal from desiccator. Weight=w2
|Possibly re-heat to constant weight|
|6. Calculation||Dry matter (DM) in percent of sample (average results of two samples to
one decimal) =
DM % = 100 x (w2 - w0) / (w1 - w0)
|7. Notes||Consider the refractive index method
|8. Reference||International Standard: ISO 1741|
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Keywords: laboratory,method,determination,dry matter,substance,starch,vacuum,oven,drying