OCR A Level Biology:复习笔记2.2.9 Biochemical Tests: Lipids

Biochemical Tests: Lipids

  • The emulsion test can be carried out quickly and easily in a lab to determine if a sample contains lipids
  • Lipids are nonpolar molecules that do not dissolve in water but will dissolve in organic solvents such as ethanol

Apparatus

  • Test tubes
  • Test tube rack
  • Ethanol
  • Pipettes
  • Food sample
  • Mortar and pestle (if food sample is solid)
  • Water
  • Gloves

Method

  • Add ethanol to the sample to be tested
  • Shake to mix
  • Add the mixture to a test tube of water

The Emulsion test for lipids forms a milky colour

Results

  • If lipids are present, a milky emulsion will form (the solution appears ‘cloudy’); the more lipid present, the more obvious the milky colour of the solution
  • If no lipid is present, the solution remains clear

Limitations

  • This test is qualitative - it does not give a quantitative value as to how much lipid may be present in a sample

转载自savemyexams

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