Inexpensive FIA method to determine trace levels of imazapyr by UV-detection enhanced with electrochemical polarization

A new flow injection analysis method with spectro-electrochemical detection (FIA/SEC) to determine trace levels of imazapyr on water samples is presented. The non-chromatographic method involves the use of a bench photometer, a single-potential potentiostat, a low pressure pumping system and a home-made spectro-electrochemical flow detector (SEC-FD), specifically adapted for the described method and using a stainless steel/electrolytic lead/lead chloride (SS/e-Pb/PbCl2) working electrode. The limit of quantification (LOQ) reached for the optimized work parameters was 0.02 µg/mL, the relative standard deviation (RSD) in the whole range of linear response was less than 2% and a wide linear response range from 0.005 to 6.0 µg/mL was obtained. A standard addition method was used to determine the imazapyr amount in natural waters containing commercial formulation of such herbicide, the Recovery % has values close to 105%. The method performance makes it suitable to analyze the legal imazapyr tolerances established by the U.S. EPA avoiding the use of expensive chromatographic equipments and/or complicated sample preparations. Keywords: Imazapyr, Flow injection analysis, Herbicide trace analysis, UV detection, Lead electrode, Water micropollutants analysis