Fluorescence polarization immunoassay of colchicine.

In this study, a fluorescence polarization immunoassay (FPIA) technique was developed to determine colchicine (COL), an alkaloid of noxious plants of the order Liliales that is used in a number of medications to treat gout. An optimal combination of the polyclonal antibody and the antigen labelled with fluorescein isothiocyanate (FITC) was selected. Conditions for the competitive interaction of the antigen in the tested samples and its fluorophore conjugate (COL-FITC) with anti-COL antibodies were optimised, and the analytical characteristics of the assay were determined. The developed FPIA was characterised by a detection limit of 1.8 ng/mL and a detectable analyte concentration range of 4.1-74.3 ng/mL. The duration of the analysis was 10 min. The applicability of the developed FPIA for quality control of ready-made drug formulations and for the estimation of COL content in various matrices (urine, milk), with recovery values ranging from 79 to 108%, was demonstrated.