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In this study; a sensitive, selective, and simple electrochemical sensor was developed to determine low concentration pyridoxine (Py) using a phosphorus‐doped pencil graphite electrode (P‐doped/PGE). Electrode modification was implemented using the chronoamperometry method at +2.0 V constant potential and 100 seconds in 0.1 mol L−1 H3PO4 supporting electrolyte solution. The characterization processes of the P‐doped/PGE were carried out using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), X‐ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray spectroscopy (EDX), and atomic force microscope (AFM) methods. In the concentration study, using the differential pulse voltammetry (DPV) method, a linear calibration plot was acquired in the concentration range of 0.5 to 300 μmol L−1 Py. The limit of quantification (LOQ) and limit of detection (LOD) of the developed method were calculated as 0.219 μmol L−1 and 0.0656 μmol L−1, respectively. Detection of Py has been successfully performed on the P‐doped/PGE in the beverage samples. As a result, the method developed has been shown to have fast, low cost, and simple for the sensitive and selective detection of Py as an effective electrode.

In this study, an electrochemical immunosensor was developed using gold nanoparticles (AuNPs), 3,4-ethylenedioxythiophene (EDOT), and pyrrole (Py) to detect carcinoembryonic antigen (CEA) sensitively. Firstly, the electrocopolymerization of PPy and EDOT was carried out on a pencil graphite electrode (PGE) by the chronoamperometry method (p(Py-co-EDOT)/PGE). Then, gold nanoparticles were electrochemically deposited on the prepared p(Py-co-EDOT)/PGEs by the chronoamperometry method. The characterizations of the developed label-free immunosensor (AuNPs/p(Py-co-EDOT)/PGE) were carried out using CV, EIS, XPS, SEM, EDX, and FTIR methods. Antibody concentration, antibody immobilization time, and immunocomplex time were optimized using differential pulse voltammetry (DPV). After optimal conditions are determined, the DPV peak current of the immunosensor decreases linearly with increasing CEA concentration of 0.001-100 ng mL À 1 . The detection limit was calculated as 0.741 pg mL À 1 from the calibration graph (S/ N = 3). The developed sensor showed excellent anti-interference ability against ascorbic acid, bovine serum albumin, dopamine, and glucose. The applicability of the developed sensor to real samples was investigated, and good recovery values were obtained. As a result, the AuNPs/p(Py-EDOT)/PGE provides lowcost, selective, and rapid detection of CEA. Our findings suggest the present immunosensor is a good candidate for application in clinical screening.

In this study; an easy, practical, and selective sensor has been developed for the electrochemical determination of riboflavin. To prepare the modified electrode, the gold nanoparticle was deposited on the pencil graphite electrode (AuNP/PGE) by the method of chronoamperometry at −3.0 V for 30 s in 0.5 M H2SO4 solution containing 10 mM tetrachloroaurate. Functionalized multi-walled carbon nanotube (f-MWCNT) solution was dropped on prepared AuNP/PGE and the functionalized multi-walled carbon nanotube/gold nanoparticle/pencil graphite electrode (f-MWCNT/AuNP/PGE) was prepared for measurements. Characterization studies of the prepared sensor were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) methods. The surface morphology of the prepared sensor was investigated by field emission scanning electron microscopy (FESEM). Differential pulse voltammetry (DPV) was used to carry out electrochemical measurements in phosphate buffer solution pH 4.0. Limit of detection (LOD) and limit of quantitation (LOQ) values were found to be 0.0352 and 0.118 μmol l−1, respectively. The fabricated sensor showed excellent anti-interference ability against ascorbic acid (AA) and glucose (G). The applicability of the constructed sensor to real samples was investigated and good recovery values were achieved. As a result, it has been seen that the modified electrode is applicable in applications of riboflavin determination.

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