Group 1
Cheyanne Thompson
Anya Bly
Christian Monaco
CHM 2045L-006
Food Dyes Analysis in Commercial Products
6-7-2022
Objective
From this lab, the group should be able to use the known concept of Spectrophotometry
to explain the direct involvement within different commercial substances of UV-Visible
radiation and molecules. Then, be able to use the spectrophotometer to determine the
nature of interaction between matter and radiation in commercial products. From the
readings, the group will compare results to the interactions between the pure dyes
results gathered previously.
Materials for Part 1
General Laboratory glassware (Volumetric Flask and Beaker)
Graduated Pipettes
Pipette Pumps
Appropriate Laboratory PPE (Lab coat, goggles, gloves, close-toed shoes)
Pencil or pen
Red Dye #3
Red Dye #40
Yellow Dye #5
Yellow Dye #6
Green Dye #3
Blue Dye #2
Any other dyes provided by TA
Ocean Optics Spectrophotometer
Cuvettes
Chemicals/Hazards
Chemical
Red Dye #3
(Erythrosine)
Formula
C20H6I4Na2O5
Molar Mass
879.86 g/mol
Properties
Liquid dye
that stains
a red color
Hazards
Not considered
hazardous, but
irritation may occur
with contact to eyes
or skin
Red Dye #40
(Allura Red
AC)
C18H14N2Na2O8S2
534.3 g/mol
Liquid dye
that stains
a red color
Not considered
hazardous, but
suspected of causing
migraines/ triggering
allergies
Yellow Dye
#5
(Tartrazine)
C16H9N4Na3O9S2
534.3 g/mol
Liquid dye
that stains
a yellow
color
Not considered
hazardous but may
trigger allergic
reactions
Yellow Dye
#6 (Sunset
Yellow FCF)
C16H10N2Na2O7S2
452.37 g/mol
Liquid dye
that stains
a yellow
color
Not considered
hazardous but may
trigger allergic
reactions
Green Dye
#3 (Fast
Green FCF)
C₃₇H₃₄N₂Na₂O₁₀S₃
808.86 g/mol
Liquid dye
that stains
a turquoiseaquamarine
color
Not considered
hazardous, but may
cause irritation when
exposed to eyes or
skin
Blue Dye #2
(Brilliant Blue
FCF)
C37H34N2Na2O9S3
792.85 g/mol
Liquid dye
that stains
a blueindigo color
Not considered
hazardous, but may
cause irritation to the
eyes
Methods and Procedures
1. Ensure all PPE is on correctly
2. Collect all necessary materials for the lab
3. Label the volumetric flasks (SS, A, B, C, D, E)
4. Add the stock solution to the SS flask
5. Create the standard solution using the following steps:
a. Weigh the stock solution
b. Add it to a clean volumetric flask
c. Add the solvent, making sure it does not fill all the way to the line
d. Once the solvent is dissolved, add more solute until the line is reached
e. Repeat to create 5 more samples
6. Place stock solution into cuvette
7. Calibrate and properly use the spectrophotometer
8. Fill a cuvette with 10 mL of solution
9. Find λmax value with spectrophotometer
10. Repeat steps 8&9 five times to ensure accurate results
11. Record found values and apply the Beer-law
12. Record initial value on the table
13. Repeat steps with other samples and record the results
14. Repeat all steps using a different dilution process
1. Collect and label 6 clean volumetric flasks.
2. Fill one flask with the dye stock solution (this will be used to create the following
solutions)
3. Ensure the spectrophotometer is turned on and properly connected to the
computer
4. Calibrate the spectrophotometer using clear and opaque cuvettes. provided
5. Fill a clear cuvette with the collected stock solution and insert it into the
spectrophotometer
6. Identify the λmax of the stock solution, and record the data
7. Ensuring that you end with a 10 mL solution, create a new solution by adding
water (the solvent) and an amount of the collected stock solution into a new
volumetric flask
8. Mix the solution so that the appearance is uniform
9. Fill a clean, clear cuvette with the new solution and insert it into the
spectrophotometer.
10. Using the previous λmax found using the stock solution, find the value on the
new solution’s calibration plot that corresponds and record
11. Repeat steps 7-10 until a total of 5 solutions containing varying dye
concentrations have been created and the corresponding λmax values have
been recorded
Calculations
Concentration:
Example: (20)(0.1)=(M2)(0.5)
M2=(20)(0.1)/(0.5)=4
Beer’s Law:
A=εCl (y=mx+b)
C=A/lε
A= absorbance
ε= molar absorptivity (L/mol-cm)
C= concentration of absorbing species (mol/L)
l= path length (cm)
Example:
ε= 4.5 L/mol-cm
C= 0.95 mol/L
l= 1 cm
A= (4.5)(0.95)(1) = 4.275
Dilutions:
Stock Concentration: 0.1
Dilutions to concentrations 0.09, 0.075, 0.05, 0.025, and 0.01
0.09 Parallel dilution: Transfer 90 mL of solution to a 100 mL volumetric flask and fill the
rest with water to receive a 0.09 M concentration (Ratio 9/10).
0.075 Parallel dilution: Transfer 75 mL of concentration to a 100 mL volumetric flask and
fill the rest with water to receive a 0.075 M concentration (Ratio 7.5/10).
0.05 and 0.025 Serial dilution: Start with 50 mL of solution, transfer 25 mL to a new flask
and add 25 mL of water. This will result in a 0.05 M concentration (Ratio 5/10). Take the
resulting solution and transfer 25 mL to a new flask and add 25 mL of water. This will
result in a 0.025 M concentration (Ratio 2.5/10).
0.01 Parallel dilution: Transfer 10 mL of concentration to a 100 mL volumetric flask and
fill the rest with water to receive a 0.01 M concentration (Ratio 1/10).
Table for data collection:
Colors
λMax (cm-1)
ε (Lmol-1cm-1)
Experimental Theoretical Experimental Theoretical
R2 Concentration Concentration
(M) sample 1 (M) sample 2