Method and apparatus for performing multiple, simultaneous in vitro diagnostic tests using a solid phase system

A method for simultaneously assaying a fluid sample for at least two different unknown mobile components contained therein which method comprises:

• (a) placing said fluid sample inside a receptacle having immobilized on its inner surface at least one fixed component reactive with at least one mobile component of the fluid sample and also containing a solid coated insert so positioned as to contact said fluid sample, which coated insert has immobilized on its surface in contact with said fluid sample at least one fixed component which is different from any fixed component immobilized on the inner surface of said receptacle and is reactive with at least one of the mobile components of the fluid sample that is unreactive with any fixed component immobilized on the inner surface of said receptacle,
• (b) allowing the mobile components of the fluid sample to react with the fixed components immobilized on the receptacle inner surface and on that surface of the solid insert in contact with the sample for a predetermined time period and,
• (c) determining the concentration of each reactive mobile component originally present in said fluid sample based on the amount of each of said reactive mobile components that reacted with each of said reactive fixed components during said predetermined time period.