Using Fluorescence Spectroscopy to Determine the Chlorophyll C

Report
Using Fluorescence Spectroscopy to
Determine the Relative Chlorophyll
Concentrations of Vegetables
Jane Kim & Rebecca Long
Ch251B – Instrumental Analysis Lab
Professor A. Newmark
Background – Why Chlorophyll?
• Health benefits in chlorophyll:
- Blocks absorption of carcinogens
- Helps regenerate blood
- Prevents bad breath and body odors
- Promotes wound healing
Solution Analyzed - Chlorophyll extract
• Chlorophyll extract: contained a combination
of several kinds of chlorophyll, most likely
majority was chlorophyll a (most prevalent)
Chlorophyll c1
Chlorophyll a
Chlorophyll b
Chlorophyll d
Chlorophyll c2
Experimental
1. Ground vegetables in acetone and water
2. Added hexane
3. Mixed thoroughly
4. Let stand for layers to form
5. Extracted hexane layer  chlorophyll extract
6. Analyzed extracts using fluorescence
spectrophotometer
Results
• Gopal et al. reported chlorophyll fluorescence
peak at ≈ 660 nm
Figure 1. Fluorescence absorption spectrum of chlorophyll
• Our fluorescence spectra peaks occurred at
similar wavelengths ✔
Results
• Beer’s Law: A = ebc,
(A = absorbance, e = molar absorbtivity, b = path length of sample, c = concentration
of compound in solution)
Absorbance of chlorophyll α Concentration of chlorophyll
• Order of Relative Chlorophyll Concentrations:
spinach > broccoli rabe > cilantro > broccoli > cauliflower
Fluorescence Absorption Spectra of All Samples
Fluorescence Absorbances
Conclusions
• Eating spinach provides the greatest chlorophyll
health benefits
• Confirmed! – The degree of the vegetable’s green
color corresponds to the concentration of chlorophyll
• Plant structure confirms chlorophyll concentration

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