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On boiling with reducing sugars 3,5 dinitrosalycylic acid (DNSA) reagent changes from yellow to red.
Small volumes of the reagent and test sample are boiled for 5-10 minutes, then diluted with water and the colour read using a colorimeter.
With the Mystrica colorimeter concentrations of reducing sugar down to below 0.5mM, (90µg of glucose/cm3), can be detected using this test.
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WEAR EYE PROTECTION
TAKE CARE WITH BOILING WATER
DNSA reagent contains 0.4M NaOH
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DNSA reagent
To prepare 100cm3 of stock solution:
- dissolve 1.0g of 3,5-dinitrosalicylic acid in 50 ml of water.
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slowly add 30g sodium potassium tartrate tetrahydrate, (KNaC4H4O6ยท4H2O)
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Add 20cm3 of 2N NaOH.
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Dilute to a final volume of 100cm3 with water.
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- Label the stock solution 'IRRITANT'
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Method
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Add 0.3cm3 of the sample to be tested to 0.3cm3 of DNSA reagent in a test tube.
- Stand the test tube in boiling water for 5 -10 minutes.
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Add 3cm3 of water and read absorbance with green light.
Click to download a pdf file containing this information.
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