Event Title

Thallium (III) oxide as a mediator for the determination of Hydrogen Peroxide, Glucose and Proteins

Session

Pharmaceutical and Natural Sciences

Description

Screen printed carbon electrodes (SPCE) bulk modified with Tl2O3 were used for the amperometric detection of hydrogen peroxide in flow injection analysis (FIA) at optimum conditions of -100 mV operating potential, 0.2 mL/min flow rate and as carrier medium phosphate buffer (0.1 M, pH 7.5). The linear range of the response of screen-printed electrodes for hydrogen peroxide detection was from 5 mg/L to 200 mg/L with a detection limit (LOD) of 2.5 mg/L. The repeatability of measurements was 1.1 % RSD (n=8 measurements) and the reproducibility 1.4 % RSD (n=8 sensors). The sensor was further tested for its selectivity for the detection of H2O2 in the presence and absence of possibly interfering compounds. Besides, an amperometric biosensor was developed using the screen printed carbon electrode modified with Tl2O3, Nafion and glucose oxidase as the bio-recognition layer for the determination of glucose. Calibration curves of the glucose biosensors with an operating potential of -100 mV and a flow rate of 0.2 mL/min in the concentration range from 10 mg/L to 1000 mg/L glucose showed a quasi-linear relation between concentration and signal up to 200 mg/L. LOD was estimated as 6.6 mg/L and the repeatibility of the measurements was 2.4 % (n=7 measurements). The glucose biosensor was tested for its selectivity to possibly interfering substances which might occur in blood and exhibited negligible effect. Finally, the biosensor was used for the detection of glucose in human blood samples showing satisfactory results compared to the results obtained from a commercial glucose biosensor. Additionally, a protein biosensor using amino acid oxidase and protease was designed using SPCE bulk-modified with the mediator (Tl2O3) and a double enzyme film at the surface containing L-amino acid oxidase and a protease. The operating potential was -400 mV with bovine serum albumin (BSA) as a template analyte in the concentration range from 20 mg/L to 200 mg/L. LOD was estimated as 5.3 mg/L and the repeatability of the measurements was 2.8 % (n=3 measurements). Finally the biosensor was applied to the determination of protein in milk samples with flow injection analysis and the results were in good agreement with data obtained with a spectrophotometric method (Bradford assay).

Keywords:

Glucose, hydrogen peroxide, cyclic voltammetry, flow injection analysis

Session Chair

Valon Ejupi

Session Co-Chair

Shpend Dragusha

Proceedings Editor

Edmond Hajrizi

ISBN

978-9951-437-96-7

Location

Lipjan, Kosovo

Start Date

31-10-2020 10:45 AM

End Date

31-10-2020 12:15 PM

DOI

10.33107/ubt-ic.2020.438

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Oct 31st, 10:45 AM Oct 31st, 12:15 PM

Thallium (III) oxide as a mediator for the determination of Hydrogen Peroxide, Glucose and Proteins

Lipjan, Kosovo

Screen printed carbon electrodes (SPCE) bulk modified with Tl2O3 were used for the amperometric detection of hydrogen peroxide in flow injection analysis (FIA) at optimum conditions of -100 mV operating potential, 0.2 mL/min flow rate and as carrier medium phosphate buffer (0.1 M, pH 7.5). The linear range of the response of screen-printed electrodes for hydrogen peroxide detection was from 5 mg/L to 200 mg/L with a detection limit (LOD) of 2.5 mg/L. The repeatability of measurements was 1.1 % RSD (n=8 measurements) and the reproducibility 1.4 % RSD (n=8 sensors). The sensor was further tested for its selectivity for the detection of H2O2 in the presence and absence of possibly interfering compounds. Besides, an amperometric biosensor was developed using the screen printed carbon electrode modified with Tl2O3, Nafion and glucose oxidase as the bio-recognition layer for the determination of glucose. Calibration curves of the glucose biosensors with an operating potential of -100 mV and a flow rate of 0.2 mL/min in the concentration range from 10 mg/L to 1000 mg/L glucose showed a quasi-linear relation between concentration and signal up to 200 mg/L. LOD was estimated as 6.6 mg/L and the repeatibility of the measurements was 2.4 % (n=7 measurements). The glucose biosensor was tested for its selectivity to possibly interfering substances which might occur in blood and exhibited negligible effect. Finally, the biosensor was used for the detection of glucose in human blood samples showing satisfactory results compared to the results obtained from a commercial glucose biosensor. Additionally, a protein biosensor using amino acid oxidase and protease was designed using SPCE bulk-modified with the mediator (Tl2O3) and a double enzyme film at the surface containing L-amino acid oxidase and a protease. The operating potential was -400 mV with bovine serum albumin (BSA) as a template analyte in the concentration range from 20 mg/L to 200 mg/L. LOD was estimated as 5.3 mg/L and the repeatability of the measurements was 2.8 % (n=3 measurements). Finally the biosensor was applied to the determination of protein in milk samples with flow injection analysis and the results were in good agreement with data obtained with a spectrophotometric method (Bradford assay).