Colorimetric principles applied to designing test kits for medical diagnosis

Many diseases involve the introduction into the body of highly specific foreign substances (antigens) to which the body responds by producing complementary antibodies. A test method has been developed whereby several different antigens can be detected simultaneously. One drop of fluid (e.g., blood serum, urine, saliva, etc.) from the patient is mixed with one drop of reagent on a card. Within two minutes a colour change takes place, each colour developed being diagnostic of a particular antigen. This paper describes the test and shows how colorimetric methods were used to optimise its performance, standardise the materials used, and determine the requirements for proposed further development.