Lab 5 Green Plant I

last updated Feb. 7, 2002 back to lab 5

SPECTROPHOTOMETRY

ABSORPTION SPECTRUM.OF PIGMENTS

You could use a pair of scissors and cut one of the regions of pigment (suspected to be chlorophyll a, chlorophyll b, carotene or xanthophyll ) from a chromatogram. If you placed that piece of paper with the pigment into a test tube containing acetone, the pigment would dissolve into the acetone solvent. This would produce a very dilute solution of the pigment. Four concentrated pigment solutions (one each for chlorophyll a, chlorophyll b, carotene and xanthophyll) pigment were prepared for you by chemically extracting chloroplast pigments from leaves of English Ivy. These concentrated pigment solutions are contained in separate spectrophotometric cuvettes.

Use these tubes to measure absorbance with a spectrophotometer. Measure absorbance at 25 nm intervals throughout the visible wavelengths (400-700 nm).
Use an appropriate reagent blank (cuvette containing solvent but no pigment) to calibrate the spectrophotometer.
 

  • Spectronic 20 Instructions in use of spectrophotometer
  • Spectronic 20 - Operating instructions
  • Spectronic 20 - Operating instructions
  • Spec 20 -

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    Spectronic 20
    Zero and calibration dials

    Selecting wavelength

    Inserting sample
    Top scale = % Transmittance
    Lower scale = Absorbance    		 

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