I Abstract

The goal of this experiment was to measure the physical properties of dextran, sucrose and glucose. Measuring the physical properties of these three sugars is fundamental in our experiment. we assume that glucose will be stained by our stains. Then, dextran and sucrose will not decompose. We set the three sugars into different concentrations and then put them in a water bath. Finally, the absorbance of solution is finally measured by the microplate reader.

II Background and Hypothesis

1. Our colorant is called DNS which will react with the reducing sugar in a 100 ℃ water bath;

2. Glucose is found in our literature to be a reducing sugar. We assume that DNS colorant reaction, the higher the concentration, the higher the absorbance of the solution after the reaction (OD540);

3. Dextran and sucrose are not reducing sugars, DNS does not react with them, so their concentrations are not related to absorbance.

III Purpose

1. Construct the standard curve between the concentration of glucose and its absorbance.

2. Considering sucrose and dextran, in the polymer state, are not the reducing sugar and do not react with DNS. But their monsters will react with them. So we measured two other factors that could cause their decomposition, pH and temperature. Taking into account the effects of the external environment on Dextran and sucrose in the real reaction, we control the variables separately and design experiments on the pH and hydration of dextran under thermal conditions.

IV Experiment Protocol

Experiment: glucose standard curve

1. Configure 1 mg/ml standard glucose solution, converse it to 250 mg/250 ml (adding 0.25 g glucose with distilled water to the constant volume of the 250ml volumetric flask)

2. Use the solution in the first step as stock liquor, take 0, 0.2, 0.4, 0.6, 0.8, 1.0 ml from it into the 15 ml test tube adding distilled water to 1ml.

3. Add 2ml DNS into each tube.

4. After adequate mixing, put each tube in 100 °C water bath for two minutes.

5. After cooling, add distilled water to the solution to 15ml.

6. Take 100ul from each tube into the labelling board, note down the positions of solutions in different concentrations.

7. Use microplate reader to measure solutions’ absorbance at 540 nm wave length and use distilled water as the control group.

8. The resulted data were photographed and kept as excel in USB flash disk.

Experiment: preparation of the measurement of dextran thermal stability and acid stability

· Acid stability preparation

1. Take 1g dextran and dissolve it into 12.5ml Tris-HCl buffer and 12.5ml DD water.

2. Divide the solution into three parts and mark clearly (acid/ alkaline/ neutral +dex).

3. A small beaker can be used to add three drops of concentrated sulphuric acid into the portion marked "acid" and two grains sodium hydroxide into the portion marked “alkali”. Mix each portion uniformly and leave the “neutral” portion unchanged.

4. Take 100ul from each portion into a 2 ml tube and mark it (acid/ alkaline/ neutral+dex). Let them stand on the finger tube frame.

Experiment: preparation for measurement of sucrose thermal stability and acid stability

· Acid stability preparation

1. Take 1g sucrose and dissolve it into 12.5ml Tris-HCl buffer and 12.5ml DD water.

2. Divide them into three parts and mark clearly (acid/ alkaline/ neutral +dex).

3. A small beaker can be used to add three drops of concentrated sulphuric acid into the portion marked "acid" and two grains sodium hydroxide into the portion marked “alkali”. Mix each portion uniformly and leave the “neutral” portion unchanged.

4. Take 100ul from each portion into a 2 ml tube and mark it (acid/ alkaline/ neutral+dex). Let them stand on the finger tube frame.

V Result

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