DEVELOPMENT OF SOLID-PHASE CHEMILUMINESCENCE IMMUNOASSAYS FOR DIGOXINCOMPARING FLOW-INJECTION AND SEQUENTIAL INJECTION TECHNIQUES

The development of a competitive solid-phase immunoassay for digoxin m aking use of the acridinium chemiluminescence system is described. Two different instrumental approaches are compared. One is based on a con tinuous flow system using a peristaltic flow injection analysis pump; the other uses a new sequential injection technique. Ln both systems a flow cell, consisting of transparent PTFE tubing packed with immobili zed antibodies, acts as an immunoreactor. The entire assay, including both the immunoreaction and the chemiluminescence reaction, takes plac e in this immunoreactor cell. Compared with the flow injection techniq ue, the sequential injection mode showed higher precision, ranging fro m 2.16 to 5.5% RSD depending on concentration. The total assay time, i ncluding regeneration, is less than 8 min with the sequential injectio n technique. The detection limit for both techniques is in the low fem tomole range.