There are many different brands of beverages that fall under the general category of “sports drinks.” Most of these beverages contain an FD&C food dye to color the beverage. There are a few options available to determine how much food dye is contained in a sports drink. A common, and very accurate, test method involves using an instrument called a spectrophotometer.
In brief, a spectrophotometer projects light through a small sample of a colored solution. The molecules in the solution allow some, but not all, of the wavelengths of light to pass through the sample and reach the spectrophotometer’s detector. By carefully analyzing what happens to light as it passes through a sample of liquid, a great deal can be learned about some of the molecules in the liquid.