Development of a flow injection capillary chemiluminescent ELISA using an imprinted polymer instead of the antibody

A flow injection competitive assay analogous to enzyme immunoassays has bee n developed using a molecularly imprinted polymer instead of the antibody. A glass capillary was modified by covalently attaching an imprinted polymer to the inner capillary wall. The herbicide 2,4-dichlorophenoxyacetic acid was used as a model analyte. The analyte was labeled with tobacco peroxidas e, and chemiluminescence was used for detection in combination with a photo multiplier tube or a CCD camera. In a competitive mode, the analyte-peroxid ase conjugate was passed together with the free analyte through the polymer -coated capillary mounted in a flow system. After a washing step, the chemi luminescent substrate was injected and the bound fraction of the conjugate was quantified by measuring the intensity of the emitted light Calibration curves corresponding to analyte concentrations ranging from 0.5 ng mL(-1) t o 50 mug mL(-1) (2.25 nM - 225 muM) were obtained. A lowered detection limi t by 2 orders of magnitude was obtained when detection was done in disconti nuous mode and the chemiluminescence light was conducted inside the photomu ltiplier tube by an optical fiber bundle, thus yielding a dynamic range of 5 pg mL(-1) - 100 ng mL(-1) (22.5 pM - 450 nM).