Abstract: A method and apparatus for controlling a stream of liquid and air segments wherein the liquid and air segments are selectively aspirated into a first fluid conduit in a plurality of cycles, each cycle beginning with the aspiration of a first air segment and ending with the aspiration of a final air segment. The liquid and air segments are then transferred from the first fluid conduit to a second fluid conduit. The volume of the final air segment of each cycle is then adjusted after the final air segment has moved into the second fluid conduit. Next, the liquid segments and the air segments of each cycle are transferred from the second fluid conduit to a third fluid conduit. The volume of the first air segment of each cycle is then adjusted after the first air segment has moved into the third fluid conduit.

Abstract: A method and reagent composition provide for the removal or blocking of serum interferences in liposome immunoassays. A carrier or liposome exhibiting at least one domain of phosphoryl ester groupings different from those of the marker liposome is introduced into the reaction mixture, whereby endogenous interfering species competitively bind to such carrier or liposome rather than to the marker liposome. Also, soluble phosphoryl ester groupings can be introduced into the reaction mixture which react with such endogenous species and further reduce serum interferences.