RP 11 Production of a dilution series of a glucose solution and use of colorimetric techniques to produce a calibration curve with which to identify the concentration of glucose in an unknown ‘urine’ sample.

Method

- Create dilution series of glucose using distilled water, ranging from 0 to 10 mmol dm^3. - Place 2cm^3 of each unknown sample in separate boiling tubes.

- Add 2cm^3 of Benedict’s solution to all boiling tubes. - Place boiling tubes in 90°C water bath for 4 minutes.

- Remove tubes with tongs and let them cool.

- Zero the colorimeter using cuvette with distilled water, set to red filter. - Measure absorbance of known samples in cuvette using colorimeter.

- Create calibration curve by plotting absorbance against known glucose concentrations.

- Measure absorbance of unknown samples using colorimeter, and determine glucose concentrations using calibration curve.

Risk Assessment

- Benedict’s solution: Wear eye protection; wash eyes/skin with cold water if contact occurs.

- Broken glass: Handle glassware carefully; seek medical assistance for cuts.

- Hot liquids: Use tongs for handling boiling tubes; wear eye protection; handle with care.

Conclusion:

- Plot absorbance against known glucose concentrations and draw line of best fit.

- High glucose concentration in urine sample indicates high risk of diabetes due to insufficient insulin production and liver cell sensitivity to insulin.

- Glucose concentration in urine reflects concentration in blood due to filtration in glomerulus and inability to reabsorb in proximal convoluted tubule.

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