Flow injection monitoring and analysis of mixtures of simazine, atrazine, and propazine using filter-supported bilayer lipid membranes (BLMs)

This work describes a technique for the rapid and sensitive electrochemical how injection monitoring and analysis of mixtures of the triazine herbicides simazine, atrazine and propazine using stabilized systems of filter-supported bilayer lipid membranes (BLMs) composed of egg phosphatidylcholine (egg PC) and dipalmitoylphosphatidic acid (DPPA). Injections of herbicides were made into flowing streams of a carrier electrolyte solution and a transient current signal with a duration of seconds reproducibly appeared in less than two min after exposure of the lipid membranes to the herbicides. The magnitude of this signal was linearly related to the herbicide concentration, which could be determined at sub-micromolar level. The mechanism of signal generation was related to a rapid adsorption of the triazine followed by a slow aggregative process of the herbicide at the surface of BLMs with a consequent rapid reorganization of the membrane electrostatics. Repetitive cycles of injection of herbicides have shown no signal degradation during each cycle. The time of appearance of the transient response was different for each triazine and increased to the order of simazine, atrazine and propazine which has allowed selective detection and analysis of these triazines in mixtures.