When rhodamine dye is exposed to light of a specific wavelength, it fluoresces or “glows” with light of a different, specific wavelength. The intensity of the response is directly proportional to dye concentration and may be measured precisely with a precision fluorometer. Thus an accurately-weighed quantity of dye, when mixed in a unknown volume of water, yields a measurable concentration which is inversely proportional to the volume of water (pictured).
amount of dye added to the system (micrograms) = volume of dilution (liters)
increase in dye concentration (micrograms / liter)
Bottles containing 400,000 micrograms each of dye are supplied. (Example: when diluted in 1000 gallons of water, each unit yields a concentration of about 100 micrograms / liter (light pink in color).
