New and sensitive magnetic carbon paste electrode for voltammetry determination of morphine and methadone
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ORIGINAL PAPER
New and sensitive magnetic carbon paste electrode for voltammetry determination of morphine and methadone Nahid Yousefi1 · Mohsen Irandoust1 · Maryam Haghighi1 Received: 16 January 2020 / Accepted: 29 May 2020 © Iranian Chemical Society 2020
Abstract A novel and sensitive modified magnetic carbon paste electrode (MMCPE) is introduced. Magnetic carbon paste electrode (MCPE) was fabricated by a ring magnet that was put behind an insulin syringe packed with a mixture of graphite powder, multi-walled carbon nanotube (MWCNT), and paraffin oil. The surface of the MCPE was modified by immersing the electrode in a suspension of nanomagnetic core-shell (Fe3O4@SiO2) for 20 s, while nanomagnetic core-shells were physically adsorbed on the surface of the electrode by the magnetic force. The electrochemical behavior of morphine and methadone was studied at this new modified electrode. The efficiency of MMCPE was compared with a simple CPE and two modified CPEs prepared by mixtures of (graphite + MWCNT) and (graphite + MWCNT + nanomagnetic core-shell). The results showed that the sensitivity of MMCPE was higher than the three other CPEs. As a result, direct attachment of Fe3O4@SiO2 magnetic nanoparticles to the surface of the CPE by the magnetic force showed much higher surface area and electrode sensitivity compared to when the NPs were mixed with other compounds. Our studies showed this electrode is not selectable and can be used as a general electrode for all electro-active compounds. The electro-active surface area of MMCPE was obtained by Randles–Sevcik equation. Square wave voltammetry (SWV) was applied for determination of morphine and methadone in a linear range of 5.0 × 10–9 to 1.8 × 10–6 M and 1.0 × 10–8 to 8.0 × 10–6 M, with detection limits of 1.6 nM and 3 nM, respectively. Eventually, the proposed electrode was applied to determine morphine and methadone in urine samples. Keywords Morphine · Methadone · Magnetic CPE · Nanomagnetic core-shell · MWCNT · Urine samples
Introduction Morphine and methadone (Scheme 1a, b), are a group of pain killer drugs. These drugs can be toxic and deadly if overdosed and can cause disorder in the central nervous system. Therefore, it is necessary to sensitively determine their concentrations in a patient’s blood or urine. A range of methods have been reported for the detection of morphine [1–6] and methadone [7–16]. Electrochemical methods due to their low cost, ease of operation, and high sensitivity and selectivity received the attention of researchers. Various electrochemical methods have been used recently to measure morphine [17–23] and methadone [24–27].
* Mohsen Irandoust [email protected]; [email protected] 1
Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran
Carbon paste electrodes (CPE) can be easily fabricated by mixing a certain amount of carbon powder, blender or organic liquids, and a specific modifier. Because of some advantages such as low cost, easy preparation, easy modification, renewable
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