Concentration of Food Colors in Artificially Colored Beverages
Fake Hall rm#405, SUNY Cobleskill, NY
Lab Section X03
This experiment was performed to investigate and determine the concentration of food coloring in Food Club Brand Cranberry-Ginger Ale. Methods used in the experiment include; comparing the color of the sample to the 3 controls (at 5ppm, 10ppm and 15ppm) by an approximate assessment with just simple eyesight, and the use of a spectrophotometer. The color of the sample of Food Club Ginger Ale seemed to have a darker color than that of the three controls, well above 15 parts per million.
By using the spectrophotometer, set on the absorption calibration, we tested the sample at wavelengths ( lambda) of light between 400nm and 780nm. These tests were performed to determine the colors preeminently absorbed by the sample. In order to properly measure the sample with the spectrophotometer, we first had to dilute the sample to a color intensity lighter than 15 ppm. We did this by pouring 25 ml of the sample into a 50 ml graduated cylinder, and then diluting it with distilled water to the 50 ml line. This created a dilution factor of 50/25, or 2. To use the spectrophotometer, we had to obtain two cuvettes. One cuvette was filled 2/3 full with distilled water and the other cuvette filled 2/3 full with our diluted fruit drink sample. We first set the wavelength of the spectrophotometer at 400nm. We then had to zero the instrument, by placing the cuvette of distilled water into the machine and pressing the 100% T/0A button. After the instrument was zeroed, we placed the fruit drink cuvette into the instrument and recorded the absorbance. We repeated these steps, but increased the wavelength by 20nm each time. It was also necessary to re-zero the spectrophotometer at every increase in wavelength, by using the method stated above. We found that Food Club Ginger Ale strongly absorbs light between the wavelengths 480nm and 540nm, and transmits colors between 680nm and 780nm superlatively. Our sample was also found to have a max value of 500nm. This means that it absorbs blues and greens most efficiently, and transmits reds most efficiently. Because our solution appears red, these results are accurate based on two properties of colored solutions. First- a solution appears a certain color because it absorbs the complement of that color. Second- the more concentrated a solution, the more of the complementary color it absorbs. This is a linear relationship. The complement of a red color (the color of our solution) is a blue color (the color absorbed predominantly absorbed by the sample).
Next, we had to test the absorbance of the food color controls. To create these control amounts, we first had to obtain some of the food dye stated on the back of the container of Food Club Ginger Ale. The stock we used to create our samples had a concentration of 100ppm. Each sample of our controls was 50ml in volume, one concentrated at 5ppm, one at 10ppm, and one at 15 parts per million. Because we created diluted solutions, we first had to derive what volume of dye was to be diluted by the respective volume of water. By using the formula V1C1=V2C2, (volume of initial by the concentration of initial equals the volume of the product by the concentration of the product) we calculated the volume of the dye to be used in each dilution. For the 5ppm solution, 2.5ml of dye were used. For the 10ppm solution, 5ml of dye were used. For the 15ppm solution, 7.5 ml of dye were used. We first carefully measured the appropriate amount of 100ppm stock Red Dye #40 using a small graduated cylinder. We then placed this amount into a 50 ml graduated cylinder, and diluted it by pouring distilled water into the cylinder to the 50ml line.
To measure how much Red Dye #40 was in Food Club Cranberry Ginger Ale, we compared it to the known food color controls that we prepared. Specifically, we compared the amount of light absorbed by the solutions at the wavelength that is most strongly absorbed, or max. Since we had already determined the max of Red Dye #40, 500nm, we went ahead and tested the absorbance of each individual control. We filled a cuvette 2/3 full of distilled water, and placed it in the spectrophotometer. We then set the spectrophotometer at our max value (500nm), and pressed the 100% T/0A button. This brought the instrument to zero. After the instrument was set to zero, we tested each of the three controls. We filled a cuvette 2/3 full of the 5ppm control and placed it in the spectrophotometer. We repeated these steps for each control and recorded the absorbance for each.
Final results concluded that the concentration of our diluted Food Club Cranberry Ginger Ale has a concentration of 5.17ppm. By taking into account our dilution factor of 2, the absolute amount of Red Dye #40 found in Food Club Ginger Ale resulted at 10.34 parts per million.
10ml Graduated Cylinder
50ml Graduated Cylinder
3 50ml Beakers
1 25ml Beaker
15ml Red Dye #40 Stock @100ppm
25ml Food Club Cranberry Ginger Ale
These tests were performed to investigate some of the properties of Red Dye #40 in relation to light. Many beverages on the market today contain Red Dye #40, Food Club Cranberry Ginger Ale being only one of them. Hawaiian Punch and Hi-C Fruit Punch are just two of the beverages on the market that contain this dye. Scientific testing of consumer products is essential to make sure that the product is entirely safe for the consumer.
Absorbance of Red Dye #40
Sample (5.17) 0.287
Fig. 1 Absorbance at various wavelengths for Red Dye #40