Using Fluorescence Spectroscopy to Determine the Relative Chlorophyll

Using Fluorescence Spectroscopy to Determine the Relative Chlorophyll Concentrations of Vegetables Jane Kim & Rebecca Long Ch 251 B – 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 c 1 Chlorophyll a Chlorophyll b Chlorophyll d Chlorophyll c 2

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 ✔

• Beer’s Law: A = ebc, Results (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