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

•The optical absorbance is enhanced by the in situ electro-reduction of herbicide.•A tubular lead electrode was made by a flowing-bath electrodeposition procedure.•The levels of detection reached meets the legal tolerances of imazapyr.•It’s the first non-chromatographic method developed for imazapyr determination.•The only pretreatment required is set a 0.6 M ionic strength and pH equal to 0.5.