# Spectrophotometric Analysis Of Dyes

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Introduction: The objective of this experiment was to use a spectrophotometer to calculate the absorbance wavelength for the commercial dyes that were given. Light is composed of tiny particles that are called photons, just like matter is composed of tiny particles called atoms. Using the spectrophotometer you can see that different dyes absorb at different wavelengths. With all of the experimentation done the concentration, absorbance and the max wavelengths should be found. Figure 1: Schematic of a single beam UV spectrophotometer Materials: There was an array of materials needed to complete this experiment. These included .20 milligrams of red dye #3,yellow dye #5, spectrophotometer, volumetric flask, cuvettes, beakers, distilled…show more content…
Adjusting the integration time, strobe lamp, and boxcar width. After all of this is done inserting the black cuvette is the next step and storing the spectrum. Insert a blank cuvette with distilled water and then store the reference cuvette again. Next is making the dye solution in order to find the max absorbance. Mixing .20 milligrams of the commercial dye (red dye #3) with 250 ml of distilled water to get the initial concentration, the goal is basically to get the absorbency level below 1. Putting the dye solution in the blank cuvette and observe the absorbance level that it dorms. Repeat the steps five times making different dilutions to maintain multiple absorbance values. The second week was making another commercial dye solution and also testing the food dye brought into class. Calibrate the spectrophotometer the same exact way so that it does not mess up the calculations gathered. This week using yellow dye #5 mix .20 milligrams of this will 250 ml of distilled water in a volumetric flask. Make five different solutions, distilling the water each time, of new yellow dye solution and place each of the solutions in a blank cuvette to find the max absorbency of each the solutions. Next during week two the absorbency had to be found from the food that was brought in. Using a blank cuvette place the commercial liquid and calculate the concentration and absorbency and which dyes would be in this liquid. Results: Maximum wavelength of Red Dye #3 Solution Absorbance Wavelength Max Concentration Solution 1 0.489 A.U. 526 nm 9.1 x 10-6 mol/L Solution 2 0.188 A.U. 525 nm 1.8 x 10-6 mol/L Solution 3 0.705 A.U. 525 nm 1.5 x 10-5mol/L Solution 4 0.682 A.U. 525 nm 1.2 x 10-5 mol/L Solution 5 0.527 A.U. 525 nm 1.2 x 10-5 mol/L Maximum wavelength of Yellow Dye