Kinetic Determination of 2,4-Dichlorophenoxyacetic Acid by Stopped-Flow Fluorescence Polarization Immunoassay

Abstract

A kinetic metodology was applied to the determination of 2,4-dichlorophenoxyacetic acid (2,4-D) by using fluorescence polarization immunoassay (FPIA). The analytical parameter used was the initial rate of the antigen-antibody reaction which was obtained from the kinetic curve degree of polarization-time and measured in only 1 s. The stopped-flow mixing technique was used for this purpose which allows the application of the method to routine analysis. The dynamic range of the calibration graph is 10–1000 ng ml⁻¹ and the detection limit is 4 ng ml⁻¹, lower than that afforded by the conventional FPIA. The relative standard deviation was close to 4%. The method was directly applied to the analysis of river water, grape juice and white wine and the analytical recoveries ranged from 92 to 110%.

Key Words:

• 2,4-Dichlorophenoxyacetic acid
• kinetic method
• fluorescence polarization immunoassay
• stopped-flow
• environmental and food samples