detection of detection of phthalic acid esters on fe3o4@azolla modified electrode with electrochemical impedance spectroscopy method on fe3o4@azolla modified electrode with electrochemical impedance spectroscopy method

Abstract: phthalic acid esters (paes) are very widely employed as additives for polymers in plastic, particularly in polyvinyl chloride (pvc) and polyethylene terephthalate (pet), which are applied in rubber, cellulose, and in the production of styrene as well [1]. paes help to improve the flexibility, transparency, and durability of articles manufactured with polymeric matrixes due to its low production cost. unfortunately, some illegal food producers take advantage of the above feature of paes, adding paes instead of palm oil into food products to sustain the desired texture, resulting in severe harm to consumers [2]. besides intentional addition, paes migrate from plastic packaging to the articles of consumption. in this work, a sensitive and efficient electrochemical sensor was introduced and the interaction of four paes including dibutyl phthalate (dbp), dimethyl phthalate (dmp), di(2-ethylhexyl) phthalate (dehp) and dicyclohexyl phthalate (dchp) in aqueous solutions with this sensor was separately investigated by electrochemical impedance spectroscopy (eis). eis analysis is a technique that measures resistance (r), capacitance (c), and inductance (l) by monitoring the current response while an ac voltage is applied to an electrochemical cell [3]. the surface of a copper electrode was modified by fe3o4@azolla paste prepared using fe3o4@azolla powder and the electroencephalography gel (eeg). modifiers were characterized by fesem and tem methods. due to the nyquist plots, the charge transfer resistance (rct) of bare electrode and fe3o4@azolla electrode were 468.8 and 285.1 kω. after separately injection of 3 μg l-1 dbp, dmp, dehp and dchp, rct were obtained as 593.1, 934.4, 529.6, 469.2 kω, respectively. the linear relationships were found between δrct and the logarithm of paes concentrations and the limit of detection (lod) and limit of quantification (loq) values were in the ranges of 0.008-0.009 μg l-1 and 0.027-0.031 μg l-1. according to the results, this sensor can be used to determine paes in real aqueous samples with good recovery percentages ranging from 93.3%-99.3% (rsd < 2.45 %).