Friday, October 21, 2011

IB Biology diffusion of beetroot pigment measured using visible spectrophotometer

IB Biology on effect of ethanol/SDS on diffusion of beetroot pigment.
Effects of ethanol and SDS on the diffusion of beetroot pigment measured using visible spec
Steps to follow
  • Cut beetroot into blocks, place in water to remove red pigment due to cutting
  • Prepare 2 fold dilution of SDS/Ethanol and place 2 ml into well
  • Find max wavelength for red pigment by pipetting 1.5ml into cuvette







Max Wavelength determined using visible spectrophotometer
  • Pipette 1.5ml red pigment (diluted) into cuvette to determine the max wavelength
  • Beer Lambert Law works only for diluted beetroot solution
  • 583nm was taken

Procedure/Steps
  • Cut blocks are placed in water to wash away pigment due to cutting
  • Place blocks in diff SDS/Ethanol conc for 5 mins
  • After 5 mins, pipette solution into cuvette
  • Measure Abs at 583nm
  • Rate of diffusion = Abs change over 5 mins


Sample Data collected 
Rate of diffusion measured by
  • Absorbance change over 5 mins
  • (Final Abs - Initial Abs) / 5mins
  • Beetroot in ethanol - Blank is ethanol
  • Beetroot in SDS - Blank is SDS
  • Assumption used - Initial Abs = 0
  • Diluted ethanol/SDS is prefer as they may affect the Abs reading





Video on beetroot diffusion measured using visible spectrophotometer

IA done by my student on beetroot experiment. A beautiful experiment. Try it and have fun.

IB Biology diffusion of beetroot pigment measured using visible spectrophotometer
May need to download to view as preview in slideshare is not clear.
Thanks to all pictures used for the above post

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