Food Dye Analysis
Rong Zhang
CHM2045-010
04/16/2014
U86192398
Introduction: Our objective for this lab was to find the concentration of three separate dyes in three different products. This is important because some dyes can be dangerous at high concentrations. The concentration was found through the use of a spectrophotometer to measure the amount of light absorbed; the amount absorbed can be related to the concentration of the dye. By making a calibration curve for each dye, with concentration versus absorbance, the concentration can be found after testing the absorbance.
Method:
Create first dye solutions
Add 0.1g of one chosen dye to a 100 mL volumetric flask
Fill the flask to the 100 mL mark using H2O.
Mix by shaking
Repeat for each dye solution chosen
Store the solutions in any beaker greater than 100mL
Calculate concentration for each dye solution
Finding the absorbance
With the spectrometer setting as such:
Integration time = 25 msec
Scans to average = 20
Boxcar Width = 6
Stobe/Lamp Enable- check
Use a curvette of H2O for blanking
Put the solution in a curvette and mark the absorbance peak
Only amounts between 0.1 and 1 can be used for calibrate curve.
Blue 1 dilution
Second solution
Add 3 mL of the first blue dye solution to the volumetric flask with a pipette and fill the 97 mL with H2O. This should be labeled with concentration
Mix by shaking
Store this solution in a beaker greater than 100 mL
Third Solutions
Using the second solution of blue dye, add 10 mL to the volumetric flask with a pipette and fill the remaining with H2O
Mix by shaking
Store this solution in a beaker greater than 100 mL for absorbance testing
Repeat this step adding 18 mL, 8 mL, 14 mL, and 6 mL of the second blue dye solution
Yellow 5 dilution
Second solution
Add 1 mL of the first yellow dye solution to the volumetric flask and fill the 99 mL with H2O. This should be labeled with concentration
Mix by shaking
Store this solution in a beaker greater than 100 mL for absorbance testing
Repeat this step adding 2 mL of the first yellow dye solution
Third solution
Add 15 mL of the second solution that used 1 mL of the first to a volumetric flask and full the remainder with H2O. This should be label with concentration.
Mix by shaking
Store this solution in a beaker greater than 100 mL for absorbance testing
Repeat this step adding 25 mL of the second solution.
Red 40 dilution
Second solution
Add 3 mL of the first red dye solution to the volumetric flask and fill the 97 mL with H2O. This should be labeled with concentration
Mix by shaking
Store this solution in a beaker greater than 100 mL
Third solution
Add 33 mL of the second solution to a volumetric flask and full the remainder with H2O. This should be label with concentration.
Mix by shaking
Store this solution in a beaker greater than 100 mL for absorbance testing
Repeat this step adding 50 mL, 67 mL, and 58 mL of the second solution
Product Testing
Blue 1 (Gatorade Blue Cherry)
Dilute Gatorade Blue Cherry by mixing 30 mL with 20 mL of H2O in a 100 mL beaker.
Test for absorbance
Yellow 5 (Mountain Dew)
No dilution necessary
Shake the Mountain Dew prior to testing absorbance to reduce bubbles.
Red 40 (Gatorade Fruit Punch)
Dilute Gatorade Fruit Punch by mixing 10 mL with 40 mL of H2O in a 100 mL beaker.
Test for absorbance
Results/Discussion:
Figure 1. Blue Calibration Curve
X-axis is concentration. Y-axis is absorbance
Figure 2. Yellow Calibration Curve
X-axis is concentration. Y-axis is absorbance
Figure 3. Red Calibration Curve
X-axis is concentration. Y-axis is absorbance Theoretically, the relationship between absorbance and concentration is linear. This means that the slope () should equal 1 in the calibration curve. Using the equation given by the Calibration Curve we can find the concentration of the products using the absorbance found.
Blue 1 (Gatorade