There are five primary color-tests reagents used for general screening purposes. The Marquis reagent turns into a variety of colors when in the presence of different substances. Dille-Koppanyi reagent uses two chemical solutions which turns a violet-blue color in the presence of barbiturates. Duquenois-Levine reagent is a series of chemical solutions that turn to the color of purple when the vegetation of marijuana is added. Van Urk reagent turns blue-purple when in the presence of LSD. Scott Test's chemical solution shows up as a faint blue for cocaine base. 
These eye drops and ointments contain a combination of a steroid and one or more types of antibiotic for treatment of infection and inflammation of the eye. The steroid reduces inflammation while the antibiotic treats or prevents infection which may be the cause of the infection. Examples of steroids that are used in these eye drops are hydrocortisone, loteprednol, prednisolone, and dexamethasone . Examples of antibiotics used in these formulations include tobramycin, neomycin, bacitracin, polymixin B, and gentamycin. These antibiotics have different mechanisms of action and two or three may be combined in one formulation.