AZIAH AHMAD ARIFFIN | Universiti Teknologi Mara (original) (raw)

Papers by AZIAH AHMAD ARIFFIN

International Journal of Electrochemical Science, 2012

Poly(ortho-Phenylenediamine) was deposited as a thin film by electrochemical impedance spectrosco... more Poly(ortho-Phenylenediamine) was deposited as a thin film by electrochemical impedance spectroscopy (EIS) and compared to cyclic voltammetry (CV) on Teflon insulated Platinum–Iridium (Pt) disk microelectrode (125 μm diameter) in 300 mM phosphate buffer solution (pH 7.2). This study focuses on the electropolymerization process and electrical properties of PoPD-modified microelectrodes, using EIS technique. The estimated thickness of the PoPD film was 31 nm with conductivity of 1.1 x 10 −5 Scm −1 . The initial impedance plot shows a semicircle which characterized the charge-transfer resistance at the microelectrode/polymer interface at higher frequency and a diffusion process at lower frequency. Impedance data were fitted to the Randles and a modified Randles circuit models with χ 2 = 0.12 and χ 2 = 0.06 respectively. The capacitive behavior (phase angle = 83°) of the bare Pt microelectrode was transformed to a resistive behavior (phase angle = 13°) after the formation of PoPD layer a...

Thiourea is known to be a unique class of organic compounds especially acylthiourea since they co... more Thiourea is known to be a unique class of organic compounds especially acylthiourea since they consist excellent Hbonds donor and acceptor where it has strong ability to form metal complexation with various metal salts. Therefore, six members of acylthiourea derivatives (TH1-TH6) have been successfully synthesized and characterised using selected spectroscopic and analytical methods namely Fourier-Transform Infrared (FT-IR) spectroscopy, UV-visible (UV-vis) spectrophotometer, and CHNS elemental analysis. In turn, all the synthesised TH1-TH6 were used to investigate the anti-bacterial activity towards selected bacteria of both Gram-negative and positive namely Salmonella typhi and Bacillus cereus respectively. TH1-TH6 revealed to have good activity towards S. typhi and B. cereus with specific and broad-range spectrum activity.

The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully ele... more The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully electropolymerized and characterized by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS). The PoPD layer is formed in optimum condition of 300 mM ortho- Phenylenediamine (oPD) with neutral Phosphate Buffer Solution (PBS) at applied potential, +0.5 V. Using EIS technique; the PoPD modified electrode was applied as analytical probe in detecting the oxidation of Hydrogen Peroxide (H2O2) and Ascorbic Acid (AA). The irreversible oxidation current of H2O2 and AA are exhibits on voltammogrames on Pt bare electrode. However, the oxidation peak current for AA diminished on PoPD modified electrode as a result of PoPD layer blocked the electron transfer. It further confirmed by electrochemical impedance spectroscopy by applied lower potential at +0.2 V. In Nyquist impedance plot is characterized by semicircle that represents the charge transfer resistance of oxidized species. It is ...

Poly-ortho-phenylenediatnine (PoPD) has been successfully electropolymerized and characterized on... more Poly-ortho-phenylenediatnine (PoPD) has been successfully electropolymerized and characterized on Platinum disk (125 urn internal diameters) using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CY). oPD was first prepared using CV by dissolving oPD monomer into Phosphate Buffer Saline (PBS) using various monomer concentration, pH of PBS and scan rate to determine the optimum condition. The optimum condition (300 mM oPD in pH 7.2 PBS with scan rate 100 mVs⁻¹ ) recorded oxidation potential E =500 mV at the highest anodic peak current, 9.16 x 10⁵ mA cm⁻². Electropolymerization of oPD was carried out by EIS with applying the optimum condition and oxidation potential to determine the redox-kinetic parameters and electrical behavior of the system. Up to our knowledge, oPD electropolymerization on Pt disk microelectrode is firstly reported in this work. Theredox-kinetic parameters of PoPD obtained from impedance data are charge transfer resistance, Rct (1.80x 10² kΩ),...

The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully ele... more The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully electropolymerized and characterized by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS). The PoPD layer is formed in optimum condition of 300 mM ortho-Phenylenediamine (oPD) with neutral Phosphate Buffer Solution (PBS) at applied potential, +0.5 V. Using EIS technique; the PoPD modified electrode was applied as analytical probe in detecting the oxidation of Hydrogen Peroxide (H 2 O 2) and Ascorbic Acid (AA). The irreversible oxidation current of H 2 O 2 and AA are exhibits on voltammogrames on Pt bare electrode. However, the oxidation peak current for AA diminished on PoPD modified electrode as a result of PoPD layer blocked the electron transfer. It further confirmed by electrochemical impedance spectroscopy by applied lower potential at +0.2 V. In Nyquist impedance plot is characterized by semicircle that represents the charge transfer resistance of oxidized species. I...

International Journal of Electrochemical Science, 2012

Poly(ortho-Phenylenediamine) was deposited as a thin film by electrochemical impedance spectrosco... more Poly(ortho-Phenylenediamine) was deposited as a thin film by electrochemical impedance spectroscopy (EIS) and compared to cyclic voltammetry (CV) on Teflon insulated Platinum–Iridium (Pt) disk microelectrode (125 μm diameter) in 300 mM phosphate buffer solution (pH 7.2). This study focuses on the electropolymerization process and electrical properties of PoPD-modified microelectrodes, using EIS technique. The estimated thickness of the PoPD film was 31 nm with conductivity of 1.1 x 10 −5 Scm −1 . The initial impedance plot shows a semicircle which characterized the charge-transfer resistance at the microelectrode/polymer interface at higher frequency and a diffusion process at lower frequency. Impedance data were fitted to the Randles and a modified Randles circuit models with χ 2 = 0.12 and χ 2 = 0.06 respectively. The capacitive behavior (phase angle = 83°) of the bare Pt microelectrode was transformed to a resistive behavior (phase angle = 13°) after the formation of PoPD layer a...

Thiourea is known to be a unique class of organic compounds especially acylthiourea since they co... more Thiourea is known to be a unique class of organic compounds especially acylthiourea since they consist excellent Hbonds donor and acceptor where it has strong ability to form metal complexation with various metal salts. Therefore, six members of acylthiourea derivatives (TH1-TH6) have been successfully synthesized and characterised using selected spectroscopic and analytical methods namely Fourier-Transform Infrared (FT-IR) spectroscopy, UV-visible (UV-vis) spectrophotometer, and CHNS elemental analysis. In turn, all the synthesised TH1-TH6 were used to investigate the anti-bacterial activity towards selected bacteria of both Gram-negative and positive namely Salmonella typhi and Bacillus cereus respectively. TH1-TH6 revealed to have good activity towards S. typhi and B. cereus with specific and broad-range spectrum activity.

The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully ele... more The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully electropolymerized and characterized by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS). The PoPD layer is formed in optimum condition of 300 mM ortho- Phenylenediamine (oPD) with neutral Phosphate Buffer Solution (PBS) at applied potential, +0.5 V. Using EIS technique; the PoPD modified electrode was applied as analytical probe in detecting the oxidation of Hydrogen Peroxide (H2O2) and Ascorbic Acid (AA). The irreversible oxidation current of H2O2 and AA are exhibits on voltammogrames on Pt bare electrode. However, the oxidation peak current for AA diminished on PoPD modified electrode as a result of PoPD layer blocked the electron transfer. It further confirmed by electrochemical impedance spectroscopy by applied lower potential at +0.2 V. In Nyquist impedance plot is characterized by semicircle that represents the charge transfer resistance of oxidized species. It is ...

Poly-ortho-phenylenediatnine (PoPD) has been successfully electropolymerized and characterized on... more Poly-ortho-phenylenediatnine (PoPD) has been successfully electropolymerized and characterized on Platinum disk (125 urn internal diameters) using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CY). oPD was first prepared using CV by dissolving oPD monomer into Phosphate Buffer Saline (PBS) using various monomer concentration, pH of PBS and scan rate to determine the optimum condition. The optimum condition (300 mM oPD in pH 7.2 PBS with scan rate 100 mVs⁻¹ ) recorded oxidation potential E =500 mV at the highest anodic peak current, 9.16 x 10⁵ mA cm⁻². Electropolymerization of oPD was carried out by EIS with applying the optimum condition and oxidation potential to determine the redox-kinetic parameters and electrical behavior of the system. Up to our knowledge, oPD electropolymerization on Pt disk microelectrode is firstly reported in this work. Theredox-kinetic parameters of PoPD obtained from impedance data are charge transfer resistance, Rct (1.80x 10² kΩ),...

The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully ele... more The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully electropolymerized and characterized by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS). The PoPD layer is formed in optimum condition of 300 mM ortho-Phenylenediamine (oPD) with neutral Phosphate Buffer Solution (PBS) at applied potential, +0.5 V. Using EIS technique; the PoPD modified electrode was applied as analytical probe in detecting the oxidation of Hydrogen Peroxide (H 2 O 2) and Ascorbic Acid (AA). The irreversible oxidation current of H 2 O 2 and AA are exhibits on voltammogrames on Pt bare electrode. However, the oxidation peak current for AA diminished on PoPD modified electrode as a result of PoPD layer blocked the electron transfer. It further confirmed by electrochemical impedance spectroscopy by applied lower potential at +0.2 V. In Nyquist impedance plot is characterized by semicircle that represents the charge transfer resistance of oxidized species. I...