Biochemical Tests
- Created by: ellie_finch
- Created on: 25-05-14 18:09
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- Biochemical Tests
- Reducing Sugars
- Add Benedict's Reagent in excess to a sample
- Heat the sample but do not let it boil
- If the test is positive, a precipitate will form
- This will change from blue through to brick red depending on the amount of reducing sugar
- Non-Reducing Sugars
- Boil test solution with hydrochloric acid and the neutralise with sodium hydrogen carbonate
- Check if reducing by completing reducing sugar test. If no result, try non-reducing sugar test
- Carry out reducing sugar test
- Starch
- Add iodine dissolved in potassium iodide solution
- If test is positive, solution changes colour from orange to blue-black
- Lipids
- Shake substance with ethanol for about a minute, then pour into water
- If lipid is present, solution turns milky. If not, solution stays clear
- Quantitative Benedict's Test
- Make up several different glucose solutions of different, known conc. and same volume
- Carry out Benedict's Test using same volume of reagent and remove precipitate by centrifuge
- Calibrate colorimeter using distilled water solution to 0, then measure absorbency of Benedict's solution left over
- Draw calibration curve showing absorbance against glucose conc. and use this to find unkown
- Reducing Sugars
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