RP 11: concentration Of Glucose In Unknown Urine Sample

Question 1

How to produce calibration curve for glucose?

Answer 1

1) Use distilled water & glucose solution of known concentration to produce dilution series

2) Heat a set volume of each solution with a set volume of Benedict’s solution

3) Measure absorbance of light of each solution using colorimeter

4) Plot graph of absorbance (y-axis) against glucose concentration (x-axis)

5) Draw line of best fit

Question 2

Describe how concentration of glucose in unknown ‘urine’ sample can be identified using calibration curve

Answer 2

1) Perform Benedict’s test on samople using same volumes

2) Measure absorbance using calorimeter

3) Absorbance value for ‘urine’ read off calibration curve to find associated glucose concentration

Question 3

Variables that should be controlled

Answer 3

1) Volumes of sample used

2) Volume of Benedict’s solution

3) Temperature of water bath

4) Time samples were heated for in water bath

Question 4

Why does high glucose concentration cause glucose to be present in the urine of a diabetic person?

Answer 4

1) Not all glucose reabsorbed at proximal convoluted tubule

2) As glucose carrier / co-transporter proteins are saturated