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Amperometric detection of morphine at a Prussian blue-modified indium tin oxide electrode
Kuo-Chuan Ho1, Chia-Yi Chen, Huan-Cheng Hsu
1Department of Chemical Engineering, National Taiwan University, Room 110A, 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan. kcho@ntu.edu.tw
Abstract:
In this work, the electrocatalytic oxidation of morphine (MO) at an optically transparent indium tin oxide (ITO) electrode modified by an electrodeposited Prussian blue (PB) thin film is first demonstrated, and the amperometric detection of MO was then investigated. Experimental results showed that the thin film on the ITO surface, confined to the PB/Berlin green (BG) redox pair, can serve as an excellent mediator which facilitates electron transfer and considerably lowers the overpotential required, as compared to a bare ITO electrode. Thus, PB can be regarded as a promising artificial peroxidase for MO. The rate of such an electrocatalytic reaction is pH dependent with the highest value at pH 5. By potential-step excitation from 0.55 to 0.70 V, a linear calibration curve, displaying the relationship between steady-state currents and MO concentrations (ranging from 0.09 to 1.0 mM), was obtained. The detection sensitivity is about 16.8 microA/cm2 mM. Most importantly, the method described herein can readily discriminate MO analogs lacking the phenolic -OH group, such as codeine, and can thus benefit the specific recognition of MO.
Insights
This study demonstrates Prussian blue (PB) modified electrodes for electrocatalytic oxidation and detection of morphine (MO). The PB thin film acts as an artificial peroxidase, enabling sensitive and specific MO detection.
Area of Science:
- Electrochemistry
- Analytical Chemistry
- Materials Science
Background:
- Morphine (MO) detection is crucial in forensic and clinical analysis.
- Developing efficient electrocatalysts for MO oxidation is an ongoing research area.
- Prussian blue (PB) is known for its electrocatalytic properties and redox activity.
Purpose of the Study:
- To demonstrate the electrocatalytic oxidation of morphine (MO) using a Prussian blue (PB) modified indium tin oxide (ITO) electrode.
- To investigate the amperometric detection of MO facilitated by the PB thin film.
- To evaluate the specificity of the method for MO detection over its analogs.
Main Methods:
- Electrochemical deposition of a Prussian blue (PB) thin film onto an optically transparent indium tin oxide (ITO) electrode.
- Electrocatalytic oxidation of MO at the modified ITO electrode.
- Amperometric detection of MO using potential-step excitation and analysis of steady-state currents.
- Investigation of pH dependency and discrimination of MO analogs.
Main Results:
- The PB thin film on the ITO electrode effectively mediated electron transfer, lowering the overpotential for MO oxidation compared to a bare ITO electrode.
- The electrocatalytic reaction rate was found to be pH-dependent, with optimal activity at pH 5.
- A linear calibration curve for MO detection was obtained in the concentration range of 0.09 to 1.0 mM, with a sensitivity of 16.8 microA/cm2 mM.
- The method demonstrated the ability to discriminate MO from analogs lacking a phenolic hydroxyl group, such as codeine.
Conclusions:
- Prussian blue (PB) modified ITO electrodes are effective for the electrocatalytic oxidation and amperometric detection of morphine (MO).
- PB functions as a promising artificial peroxidase for MO, facilitating sensitive and specific detection.
- The developed method offers potential for the specific recognition of MO in complex samples.
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