caa a22 4500 467995982 CHVBK 20180323112557.0 cr unu---uuuuu 170328e19900501xx s 000 0 eng 10.1007/BF01244841 doi (NATIONALLICENCE)springer-10.1007/BF01244841 Liposome-based flow injection enzyme immunoassay for theophylline [Elektronische Daten] [Tai Wu, Richard Durst] Preliminary results are presented on the development of a sensitive, quantitative immunoassay based on a regenerable, flow injection analysis system incorporating a double-amplification approach. The double amplification is achieved by means of liposome-encapsulated peroxidase enzyme molecules which are released subsequent to a competitive immunological reaction with analyte molecules for immobilized antibodies. The released peroxidase enzymatically cleaves, from an organofluorine substrate, fluoride ions which are then potentiometrically measured. The entire process is carried out in a flow injection analysis system. The competition between the analyte molecules (theophylline) and theophylline-derivatized liposomes for immobilized antibody sites in flow-through immunoreactor column results in unbound liposomes being carried downstream where they are ruptured in the presence of hydrogen peroxide andp-fluorophenol. The peroxidase molecules released react enzymatically to produce fluoride ions which are measured with an ion-selective electrode. The immunoreactor column is then regenerated with a chaotropic agent and the next sample or calibration solution is injected. By means of column regeneration and calibration, accurate quantitation can be achieved; a feature missing from conventional batch-type immunoassays. By means of this liposome/enzyme double-amplification approach, theophylline was determined over a range of concentrations from 0.2 to 4000 ng/ml. The detection limit of 200 pg/ml corresponds to about 100 femtomole of theophylline measured in the 100 μl sample injected. Springer-Verlag, 1990 theophylline nationallicence enzyme immunoassay nationallicence peroxidase nationallicence flow injection analysis nationallicence liposomes nationallicence ion-selective electrode nationallicence Wu Tai Center for Analytical Chemistry, National Institute of Standards and Technology, 20899, Gaithersburg, MD, USA aut Durst Richard Center for Analytical Chemistry, National Institute of Standards and Technology, 20899, Gaithersburg, MD, USA aut Microchimica Acta Springer-Verlag 100/3-4(1990-05-01), 187-195 0026-3672 100:3-4<187 1990 100 604 https://doi.org/10.1007/BF01244841 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01244841 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Wu Tai Center for Analytical Chemistry, National Institute of Standards and Technology, 20899, Gaithersburg, MD, USA aut NATIONALLICENCE 700 1- Durst Richard Center for Analytical Chemistry, National Institute of Standards and Technology, 20899, Gaithersburg, MD, USA aut NATIONALLICENCE 773 0- Microchimica Acta Springer-Verlag 100/3-4(1990-05-01), 187-195 0026-3672 100:3-4<187 1990 100 604 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer