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Method 1)Weigh out 5g(approx. of potato granules into a clean 400ml beaker. Record the weight of sample (2)Add the sample to 250ml 2mls of distilled water in a 400ml beaker. (3)Stir on a magnetic stirrer or a minimum of 15min (4)Remove beaker from stirrer and allow contents to settle. (5) Decant the upper layer through a No. 2 filter paper pouring back the first 0-20ml of filtrate into the filter. If filtrate is not clear pour back until a clear filtrate is obtained (6 Pipette 5ml of filtrate into a boiling tub (7) Add 5ml of dilute dinitrosalicylic acid solution 8)To a second tube add 5ml distilled water and 5ml dilute dinitrosalicylic acid solution. This is the blank solution (9) Place the tubes in a vigorously boiling water bath for 10min, making sure the level of the contents in the tube is at least one inch below the surface of the boiling wat (10)Remove the test tubes and cool in cold water. (11)Transfer the cool blank solution to a clean cuvette and using a 580 filter, set the colorimeter to (12)Replace the blank solution with the sample solution and read the optical density (oD)on the absorbance scale (13)From a standard curve calculate the sugar content of the potato granules Preparation of standard Curve Into tube (1)pipette 5ml water (3)pipette 4.0ml water and 1.0ml glucose solutOn 2)pipette 4.5ml water and 05ml glucose solutio (4)pipette 3.0ml water and 2.0ml glucose solution (5)pipette 2.0ml water and 3.0ml glucose solution Draw a graph of Od against concentration of glucose solution.Method (1) Weigh out 5g (approx.) of potato granules into a clean 400ml beaker. Record the weight of sample. (2) Add the sample to 250ml f 2mls of distilled water in a 400ml beaker. (3) Stir on a magnetic stirrer or a minimum of 15min. (4) Remove beaker from stirrer and allow contents to settle. (5) Decant the upper layer through a No.2 filter paper pouring back the first 10-20ml of filtrate into the filter. If filtrate is not clear pour back until a clear filtrate is obtained. (6) Pipette 5ml of filtrate into a boiling tube. (7) Add 5ml of dilute dinitrosalicylic acid solution. (8) To a second tube add 5ml distilled water and 5ml dilute dinitrosalicylic acid solution. This is the blank solution. (9) Place the tubes in a vigorously boiling water bath for lOmin, making sure the level of the contents in the tube is at least one inch below the surface of the boiling water. (10) Remove the test tubes and cool in cold water. (11) Transfer the cool blank solution to a clean cuvette and using a 580 filter, set (12) Replace the blank solution with the sample solution and read the optical (13) From a standard curve calculate the sugar content of the potato granules. Preparation of standard Curve Into tube (1)pipette 5ml water 2)pipette (3)pipette (4)pipette (5)pipette the colorimeter to zero. density (OD) on the absorbance scale. 4.5ml water and 0.5ml glucose solution 4.0ml water and 1.0ml glucose solution 3.0ml water and 2.0ml glucose solution 2.0ml water and 3.0ml glucose solution Draw a graph of OD against concentration of glucose solution. 244
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