Patent ID: 7033839

Claim:
A method of detecting ammonia in aqueous systems, such as aquarium water, comprising: obtaining a defined sample volume of the water to be tested; contacting the defined sample volume of water with a non-ammonia alkaline agent to raise the pH to at least 10; simultaneously contacting said sample volume of water with an indicator pad comprising a porous hydrophobic barrier membrane having a front side and an opposite side and capable of allowing ammonia to pass through from said front side to said opposite side of said membrane; said membrane being coated with an excess of a pH chromogenic indicator mixture which responsively changes color upon contact with ammonia, and said membrane being impregnated with ethyl cellulose, a surfacant, and tertiary octyl phenol; observing the indicator color response on the opposite side of said membrane; and thereafter, comparing the observed intensity of the color response with standard color chart to determine ammonia concentration of said water sample.