Hashim, Norhayati
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Synergistic Effect of Acylpyrazolone Integrated with Multiwalled Carbon Nanotubes on the Electrochemical Analysis of Ascorbic Acid Mohamad Mahbob, Emi Norzehan; Ahmad, Mohamad Syahrizal; Md Isa, Illyas; Hashim, Norhayati; Ul-Hamid, Anwar; Saidin, Mohamad Idris; Suyanta, Suyanta; Ibrahim, Sofian
Makara Journal of Science Vol. 28, No. 1
Publisher : UI Scholars Hub

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Abstract

Square wave voltammetry, cyclic voltammetry, chronocoulometry, and electrochemical impedance spectroscopy were employed to assess ascorbic acid’s electrochemical behavior in multiwalled carbon nanotubes (MWCNTs)/carbon paste electrode (CPE) modified by 1-phenyl-3-methyl-4-metafluorobenzoyl-5-pyrazolone (HPMmFBP). The ascorbic acid’s irreversible oxidation peak appeared at approximately 0.5 V. The shifting of the peak potential at the pH range of 6.0–8.4 showed the involvement of protons in the ascorbic acid oxidation. Moreover, the shifting of the peak potential with scan rate in the range of 0.07–0.4 V/s confirmed that the oxidation reaction was irreversible. Under optimized conditions, the oxidative peak current showed linear dependence on the ascorbic acid’s concentration between 1 and 1000 μM with limit of detection (LOD) and quantification (LOQ) at 0.1 and 0.34 μM, respectively. HPMmFBP/MWCNT/CPE exhibit good antiinterference ability, reproducibility, repeatability, and stability and was utilized for the accurate and rapid ascorbic acid detection in commercial tablets. Therefore, it has good potential for practical application.
Photopolymerization of Imprinted Polymer with Dummy Template for the Recognition of Hydroquinone in Aqueous Medium Musali, Norlin Suhaiza; Abu Bakar, Norlaili; Abdul Rahim, Nurulsaidah; Wan Mahamod, Wan Rusmawati; Hashim, Norhayati; Mohd Sharif, Sharifah Norain; Che Soh, Siti Kamilah; Ulianas, Alizar
Indonesian Journal of Chemistry Vol 24, No 5 (2024)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.90096

Abstract

This study' purposes are to synthesize molecularly imprinted polymer (MIP) with hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) using p-xylene under ultraviolet curing at 405 nm for the recognition of hydroquinone (HQ) in aqueous medium. The template was extracted from the polymer with a mixture of methanol and acetic acid (9:1) by volume (v/v). The Fourier transform infrared (FTIR) spectrum of MIP (after wash) showed the absence of peak at the range of 840–860 cm−1, which represented the stretching outside the aromatic plane C–H at the para position (p-xylene). Field emission scanning electron microscope (FESEM) micrograph showed that the MIP had cavities compared to non-imprinted polymer (NIP). The MIP (MIP-Pxy) with ratio (monomer:crosslinker) 0.25 and 1.00% template gave the highest uptake of hydroquinone (HQ) in aqueous solution, which implied more specific recognition (highest KD value). The rebinding of HQ onto MIP-Pxy was best described by both isotherm (Langmuir and Freundlich) and kinetic model (pseudo-first and -second). The MIP was successfully synthesized using p-xylene, able to recognize HQ and was very selective to p-CP. Implication of the study, the synthesized MIP can be used for recognition and sensing materials for HQ and any similar molecules.