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 a Chlorophyll b Chlorophyll d Chlorophyll c1 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 Our fluorescence spectra peaks occurred at similar wavelengths ✔ Figure 1. Fluorescence absorption spectrum of chlorophyll

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