Finding conc of glucose in urine - using a colorimeter

Question 1

Step 1: How do u carry out a serial dilution?

Answer 1

1. Label 7 test tubes: 0.32M, 0.16M, 0.08M, 0.04M, 0.02M, 0.01M glucose solution
2. Measure 10cm3 of 0.32M glucose solution + add to test tubes
3. Add 5cm3 distilled water to all other test tubes
4. Take 5cm3 of 0.32M + put into 0.16M, repeat for all (0.16 into 0.08, etc)
5. Invert test tubes 3 times - put bung in + turn test tube upside down

Question 2

Step 2: Explain how to carry out method for reducing sugars:

Answer 2

1. Take 2cm3 of 0.32M solution + put into test tubes. Add 1cm3 of benedict’s QUANTITATIVE solution
2. Do same with all other solutions and the urine solution
3. Add test tubes to water bath for 5 mins
4. Remove + allow precipitate to settle

Question 3

How do u measure the absorbance with a colorimeter?

Answer 3

1. Label cuvette tray with glucose concentrations + urine
2. Fill cuvettes to the top with each solution + put in tray
3. Fill a cuvette with distilled water - will be ur blank
4. Make sure colorimeter is set to 0.0 + filter is set to 680nm
5. Put blank cuvette into colorimeter + press reading button. Should give absorbance of 0.0
6. Do the same with other glucose solutions
7. For urine, use blank cuvette into+ repeat steps 4, 5, and 6. Record absorbance