Method and apparatus for performing assays

Abstract

Method and apparatus are provided for carrying out multiple simultaneous transfers of fluid. The method and apparatus are particularly directed toward immunoassays wherein immunologically active compounds, such as antigens and haptens, are detected through their associated antibodies. The device relies on the ability to transfer fluids, such as biological samples and reagents, between a reservoir and an associated receptacle. By providing a receptacle having a port at its lower end and which is otherwise hermetically sealed, such fluid transfer can be effected by immersing the port beneath the surface of the fluid in the reservoir and manipulating the pressure on the remaining surface area outside the port. The transfer of biological fluids at positive pressure provides enhanced fluids flow characteristics, particularly reduction or elimination of the tendency of these fluids to froth or bubble. Moreover, since the fluids can easily be manipulated, they can be agitated to speed up the reaction and reduce the overall reaction time and can be transferred from the reaction zone to allow interim measurements of the extent of reaction to provide for a rate mode assay. The method and apparatus also find use in preparing solid phase reagents for use in assay systems, as well as a highly accurate pipetting system in analytic applications not limited to immunoassays.