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By: Shawana Khokher
ID # 20580504
Lab Partner: Dana Tucci
Teaching Assistants: Katarina Vuckovic & Monica Gromala
Section # 003
BIOL 130L (B2 149)
Tuesday (9:30am -12:20pm)
Date of Experiment: 21/10/2014
INTRODUCTION
The purpose of spectroscopy is to observe the relationship between substances in a solvent, and the associated absorbance and transmittance through a range of concentrations (Lothian & Twyman, 1969). However, one must understand the underlying principles of the electromagnetic spectrum in order to analyze the results of the techniques used in this experiment. When one notices the color of an object, they are observing the wavelengths of visible light – 400 nm to 750 nm approximately …show more content…
Fast Green solution is a green dye that reflects green wavelengths of light, while absorbing relatively all other wavelengths, specifically, in the red region of light, 600 nm (Sun & Tae, 2007). Knowing the concentration of this solution and measuring absorbance values, allows one to create a standard curve of concentration and absorbance values, which can then be used in chemical tests to determine concentrations of unknown samples with the absorbance values (Lothian & Twyman, 1969). Furthermore, the experiment uses chlorophyll to measure the wavelengths at which chlorophyll a and b have maximum absorbance. The chlorophyll extracted from spinach leaves is separated into its individual component pigments, xanthophyll, carotene, chlorophyll a and chlorophyll b, through chromatography – a process used to separate molecules based on size, charge and chemical interactions (Alberts et al., 2010). Then, chlorophyll a and b are dissolved in acetone, and through spectroscopy the wavelengths of maximum absorption are determined. Chlorophyll a and b specifically absorb wavelengths of red light at 650 nm to 680 nm, approximately, and wavelengths of blue light at 420 nm to 460 nm approximately (Karp, 2009). The absorbance of light by chlorophyll pigments is observed experimentally in this lab and shows how plants have the specific properties they do, as well …show more content…
First, the pigment had been extracted and separated into each specific component. As one can observe from Figure 4 the chromatogram indicates the presence of four distinct regions. The pigments that are seen on the chromatogram include: carotene, the orange band directly after solvent front; xanthophylls, present as the two separate yellow bands after carotene; and then finally, chlorophyll a and chlorophyll b represents the two green bands on the chromatogram (Karp 2009). The use of the chromatogram allows for the separation of chlorophyll a and b, which is then dissolved in acetone and absorbance values are calculated for each pigment (Alberts, 2009). The results are represented in Table 3 at 20 nm intervals and 5 nm intervals at wavelengths of maximum absorption. Furthermore, the results had been superimposed on a single graph in Figure 3 showing the peaks at which the wavelength is absorbed most. This data is indicative of the fact that chlorophyll a absorbs most light at 430 nm, and partially at 660 nm. Similarly, Figure 3 demonstrates that chlorophyll b absorbs light mainly at 460 nm, and moderately at 660 nm. This illustrates that both types of chlorophyll pigments absorb light in the red and blue wavelengths, while all other wavelengths had been transmitted or reflected (Karp
Insert Subtitle
By: Shawana Khokher
ID # 20580504
Lab Partner: Dana Tucci
Teaching Assistants: Katarina Vuckovic & Monica Gromala
Section # 003
BIOL 130L (B2 149)
Tuesday (9:30am -12:20pm)
Date of Experiment: 21/10/2014
INTRODUCTION
The purpose of spectroscopy is to observe the relationship between substances in a solvent, and the associated absorbance and transmittance through a range of concentrations (Lothian & Twyman, 1969). However, one must understand the underlying principles of the electromagnetic spectrum in order to analyze the results of the techniques used in this experiment. When one notices the color of an object, they are observing the wavelengths of visible light – 400 nm to 750 nm approximately …show more content…
Fast Green solution is a green dye that reflects green wavelengths of light, while absorbing relatively all other wavelengths, specifically, in the red region of light, 600 nm (Sun & Tae, 2007). Knowing the concentration of this solution and measuring absorbance values, allows one to create a standard curve of concentration and absorbance values, which can then be used in chemical tests to determine concentrations of unknown samples with the absorbance values (Lothian & Twyman, 1969). Furthermore, the experiment uses chlorophyll to measure the wavelengths at which chlorophyll a and b have maximum absorbance. The chlorophyll extracted from spinach leaves is separated into its individual component pigments, xanthophyll, carotene, chlorophyll a and chlorophyll b, through chromatography – a process used to separate molecules based on size, charge and chemical interactions (Alberts et al., 2010). Then, chlorophyll a and b are dissolved in acetone, and through spectroscopy the wavelengths of maximum absorption are determined. Chlorophyll a and b specifically absorb wavelengths of red light at 650 nm to 680 nm, approximately, and wavelengths of blue light at 420 nm to 460 nm approximately (Karp, 2009). The absorbance of light by chlorophyll pigments is observed experimentally in this lab and shows how plants have the specific properties they do, as well …show more content…
First, the pigment had been extracted and separated into each specific component. As one can observe from Figure 4 the chromatogram indicates the presence of four distinct regions. The pigments that are seen on the chromatogram include: carotene, the orange band directly after solvent front; xanthophylls, present as the two separate yellow bands after carotene; and then finally, chlorophyll a and chlorophyll b represents the two green bands on the chromatogram (Karp 2009). The use of the chromatogram allows for the separation of chlorophyll a and b, which is then dissolved in acetone and absorbance values are calculated for each pigment (Alberts, 2009). The results are represented in Table 3 at 20 nm intervals and 5 nm intervals at wavelengths of maximum absorption. Furthermore, the results had been superimposed on a single graph in Figure 3 showing the peaks at which the wavelength is absorbed most. This data is indicative of the fact that chlorophyll a absorbs most light at 430 nm, and partially at 660 nm. Similarly, Figure 3 demonstrates that chlorophyll b absorbs light mainly at 460 nm, and moderately at 660 nm. This illustrates that both types of chlorophyll pigments absorb light in the red and blue wavelengths, while all other wavelengths had been transmitted or reflected (Karp