Practical 11 Flashcards
how can Benedict’s solution be used to measure the concentration of glucose in a solution
use a colorimeter to measure the absorbance of a series of solutions of known concentrations to create a calibration curve compare the absorbance of an unknown sample to the calibration curve
what is a serial dilution
a dilution where successive concentrations increase or decrease in logarithmic fashion
outline the procedure of this practical
- make a serial dilution of glucose
- place 2cm3 of each of the unknown samples in separate boiling tubes
- add Benedict’s solution to all the boiling tubes
- place boiling tubes in a water bath at 90c for four minutes
- zero the colorimeter using a cuvette using distilled water and set o red filter
- place known samples into cuvette and measure the absorbance of each using the colorimeter
- make a calibration curve
- measure the absorbance of the unknown samples using the colorimeter. use the calibration curve to determine glucose concentrations
what are the axes in a calibration curve
absorbance against glucose concentration
what would a high glucose concentration in urine suggest
it may suggest diabetes. lack of insulin leads to high BGC
state the hazards and precautions of this practical
Benedict’s solution is an irritant, wear eye protection, avoid contact with skin.
handle the hot water bath with care
how can you increase accuracy of the estimate of the unknown glucose solution
increase the number of concentrations for the calibration curve within the range of concentrations that the unknown belongs in