Analysis of food dyes in beverage

I. PURPOSE OF EXPERIMENT

The purpose of this Lab is to use spectroscopy create graph to determine the concentration of dye in a sport drink, by creating series of standard dilutions of an FD&C Blue 1 Stock solution and measuring the percent transmittance of each dilutions. Results in each dilutions will be use, to determine the linear function among various functions (T, T%, log T, - logT) For a Beer’s law calibration curve. The produce provides a model for guided-inquiry analysis of the concentration of food dye(s) in sports drinks and other consumer beverages.

II. MATERIAL USED

Beaker, 500-mL, 1
Beaker, 100-mL,9
Pipets, serological, 10-mL, 2
Cuvets, 13 × 100 mm , 1
Sample of consumer sports drink (Gatorade Blue), 10-mL
FD&C Blue 1 stock solution, 50-mL
Distilled Water , 100 mL
Spectrophotometer
Kimwipes
Test tube rack
Lenovo Laptop
Logger Pro 3.8.7 Software
TI-84 Calculator

III. PROCEDURE
STEP 1. Turn on laptop and open Logger Pro 3.8.7.
STEP 2. Turn on spectrophotometer and connect it to laptop, warm up for 15 minute.
STEP 3. Set up an appropriate data to record measurement and the results of calculations as shown below.
Beaker
Concentration
%T
T logT -logT
A
7.0 × M

B
5.6× M

C
4.2 × M

D
2.8 × M

E
2.1 × M

F
1.4 × M

G
0.7 × M

H
0 M

Gatorade
Gatorade

STEP 4. Obtain 50 mL FD&C Blue 1 stock solution in 100 mL beaker, Label it “A”.
STEP 5. Place 7 small, clean, dry 100mL beakers and label them B through H. Add the amount of stock dye solution and distilled water according to table below. Use a 10mL graduated cylinder to carefully measure the prescribed volume of each stock solution. After adding the stock solution to the beaker and without rinsing the cylinder, use a wash bottle to add the volume of distilled water.
Solution
Stock(A)
B
C
D
E
F
G
H
Water(mL)
0
2
4
6
7
8
9
10
Stock (mL)
10
8
6
4
3
2
1
0

STEP 6. Obtain 10 mL of Gatorade in 100 mL beaker, Label Gatorade.
STEP 7. Rinse the empty cuvet with a small amount of the first sample to be measured, starting with the most dilute sample (H). Fill the cuvet 2/3 full with this solution and place it in the sample holder. Read the absorbance and record the concentration in the data table.
STEP 8. Measure the absorbance of the remaining five samples in order of increasing concentration, following the procedure in step 7.
STEP 9. Rinse the cuvet with small volumes Gatorade sample. Fill the cuvet 2/3 full and analyze the unknown solution as done previously.
STEP 10. Fill up the data record table and graph the following table
Concentration v. %T -Concentration v. T
Concentration v. logT -Concentration v. -logT
STEP 11. Determine the Linear function of graph by Calculator to find the concentration of Gatorade.

IV. DATA AND OBSERVATION

Data Table 1
Beaker
Concentration
%T
T logT -logT
A
7.0 µM
21.8
0.218
-0.661
0.661
B
5.6 µM
27.1
0.271
-0.567
0.567
C
4.2 µM
37.4
0.374
-0.427
0.427
D
2.8 µM
52.7
0.527
-0.278
0.278
E
2.1 µM
61.1
0.611
-0.213
0.213
F
1.4 µM
74.5
0.745
-0.127
0.127
G
0.7 µM
88.5
0.885
-0.053
0.053
H
0 M
100.0
1.000
0
0
Gatorade
Gatorade
29.5
0.295
-0.530
0.530

Graph 1.Concentration v. %T

Graph 2.Concentration v. T

Graph 3.Concentration v. logT

Graph 4.Concentration v. –logT

V. DATA ANALYSIS

Among graph 1-4, Graph 4 Concentration v. –log T is the most likely to be Linear function

Calculate linear function by using TI-84 calculator, using stat function
Y= 0.098X
0.530 = (0.098)(Concentration)
Concentration of Gatorade = 5.4 µM
Molarity = Mass of solute/(Molar mass * Volume (L))
Mass of solute = 0.54E-6 * 793 * 0.01
Mass of solute = 0.043 gram
VI. CONCLUSIONS & ANSWERS TO QUESTIONS

Review Question
1. Calculate the value of %T for an absorbance value A = 1.5. Using this result, explain why absorbance measurement >1 may not be accurate

For the measurement to be accurate, there must be enough light transmitted.
At absorbance reading A =-1.5 = -logT
T = 10 ^-1.5 = 0.032
%T = 0.032 * 100 = 3.2%
At this point only 3.2% of light are transmitted and it is more likely to be error than accurate.

2. Write a balanced chemical equation for the reaction of Copper (II) Sulfate and concentrated ammonia to produce tetraamminecopper (II) sulfate . +

3. solutions exhibit a deep blue-violet color.How can you use spectrophotometer to confirm that this reaction has occurred and the product formed is in fact tetraaminecopper (II) sulfate? Would you expect the wavelength of maximum absorbance(λ max) for to be greater than or less than λ max for explain?

λ max will be less than the value of λ max of
Because absorbance will shifted from red-yellow toward yellow – green

4.The electron transitions responsible for the colors of transition metal ions involve d -> d transitions. Why are zinc ions colorless in aqueous solution?

Zinc do not absorb light at wavelengths between 400-700nm. Human eye is only able to detect wavelength spectrums from between 400 nm to 700 nm .It will appear colorless to us because human eye cannot see it.

VII. PERSONAL CONCLUTIONS

This Lab is the start of AP Chemistry class. We struggled with some problems that cause from un-experienced in using each machine to work properly. We used more times than we suppose to, but in the end it is a good lab experience and the results is useful for people who drink a lot of sport drink beverage.

This is one of the most interested lab for myself. Because I drink sport drink almost every times that I have a game or practice. There is a question that how much dyes that the sport drink company put inside that plastic bottle? is it in the acceptable rate? After this Lab I realize how much food dye I have put into my body and I have to drink it less often.