AbstractThe polarographic method proved suitable for investigation of adsorption of acifluorfen (I) (5‐[2‐chloro‐4‐(trifluoromethyl)phenoxy]‐2′‐nitrobenzoic acid) on lignin. Polarographic reduction of acifluorfen in aqueous buffers (pH7 is attributed to a decrease in protonation rate of the reduction intermediate. Unsubstitutedp‐nitrophenyl phenyl ether (II) shows an analogous behavior. Reduction wave of the nitro group can be used for determination of aciflurofen (I), fluorodifen (III), oxyfluorfen (IV), and bifenox (V) in the 1 × 10−5to 5 × 10−4M range. Adsorption of acifluorfen depends on th