2684 hits

This study aims to develop a voltammetric sensors of acetaminophen, dopamine and hydroquinone using zinc layered hydroxide-L-phenylalanate/multiwalled carbon nanotubes, zinc layered hydroxide-sodium dodecyl sulphate-isoprocarb/multiwalled carbon nanotubes and zinc layered hydroxide-ferulate/multiwalled carbon nanotubes, respectively. The surface morphology of these layered materials and multiwalled carbon nanotubes were determined using scanning electron microscope and transmission electron microscope, while the rate of electron transfer on the surface of these electrodes were determined by electrochemical impedance spectroscopy. The square wave voltammetry method was used to study the performance of these electrodes. Several experimental conditions influencing the voltammetric responses such as percentage of modifiers, type and concentration of supporting electrolyte, pH of the solutions and square wave voltammetry parameters were optimized. Under optimum conditions, these electrodes .....

1521 hits

Study on the chemical constituents of the dichloromethane (DCM) crude extract of Platymitra siamensis Craib has led to the isolation of four oxoaporphine alkaloids. The compounds were identified as liriodenine (1), Omethylmoschatoline (2), lysicamine (3) and cepharadione-A (4) which were isolated first time from this species. The structures of the isolated compounds were elucidated based on their spectral data (1H, 13C and LCMS) and reports in the literature. Here we observed that, only alkaloid 1 exhibited obvious cytotoxic effects against MCF-7 human breast cancer cells line with IC50 value of 31.26 µM. This work is the first attempt on phytochemical and bioactivity study on the genus of Platymitra...

948 hits

A sensitive and selective electrochemical sensor for detection of dopamine (DOP) using zinc layered hydroxide-sodium dodecyl sulphate-isoprocarb (ZLH-SDS-I)/multiwalled carbon nanotubes (MWCNT) in 100 mM phosphate buffer solution (PBS) and at the pH 8.0 was developed. The morphology and electrochemistry properties of ZLH-SDS-I/MWCNT nanocomposites were characterized using square wave voltammetry (SWV), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedence spectroscopy (EIS) and scanning electron microscopy (SEM). Under optimized conditions, the linear analytical curve for determination of dopamine was 1.0 µM to 0.3 mM with the detection limit of 0.43 µM. Besides that, the proposed sensor also exhibited good selectivity, stability, sensitivity and was found to be applicable for dopamine detection in the commercial dopamine hydrochloride injection samples.  ..

1929 hits

Numerous analytical approaches have been developed to determine histamine levels in food samples due to its health consequences. Consuming histamine over the Food and Drug Administration (FDA)-regulated 50 mg kg-1 limit would result in chronic toxicity. Consequently, the present study discusses a novel electrochemical approach to evaluate histamine levels in fish products via a molecularly imprinted polymer (MIP) on an electrode surface. The film was produced with electropolymerized polyurethane (PU), which maintained the histamine compound. Fourier-transform infrared (FTIR) spectroscopy was applied to verify the MIP manufactured in this study. The capability of the polymer was measured by assessing its electron shifts with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was also employed to validate the sensing method. The MIP/screen-printed electrode (SPE) and non-imprinted polymer (NIP)/SPE recorded a linear response ran.....

226 hits

This work explicates a simple, rapid, and sensitive method for the electrochemical detection of dopamine (DOP) utilising 1-phenyl-3-methyl-4-orthofluorobenzoyl-5-pyrazolone (HPMoFBP)/multiwalled carbon nanotube (MWCNT) carbon paste electrode (CPE). The electrochemical behaviour of DOP was performed through cyclic voltammetry and square wave voltammetry. HPMoFBP/MWCNT showed a higher current at the lower potential for the oxidation of DOP compared to bare MWCNT. The sensor's improved electrocatalytic activity was observed to detect in a 1.0 x 10-1 M phosphate buffer saline (PBS) solution at pH 8.0. A good linear regression analysis was observed between electrical response and the concentration of DOP in the range of 1 to 1000 M. Under optimized experimental conditions, 1.0 x 10-7 M has been determined as the limit of detection (LOD). The sensor has expressed considerable sensitivity towards DOP detection without interference and is successfully used to determine DOP in dopamine hydrochl.....

217 hits

The toxicity of histamine has attracted numerous researchers to develop a method for histamine determination purposes. The Food and Drug Administration (FDA) unequivocally prohibits the consumption of histamine above 50 mgkg-1. Thus, an innovation in histamine detection in fish has been developed in this research. The investigation of the histamine level in fish has been conducted by using an electrochemical sensor approach and producing a polymer via molecularly imprinted polymer (MIP) on a screen-printed electrode. The technique was validated by assessing the shifts in electron shifting using the cyclic voltammetry (CV) approach and electrochemical impedance spectroscopy (EIS), whereas differential pulse voltammetry (DPV) was applied to validate the sensor method. The instruments showed a linear response ranging from 1-1000 nmolL-1, with a detection limit of MIP/SPE at 1.765 nmolL-1 and 709 nmolL-1 for the NIP/SPE, respectively. The sensing technique was employed to determine the his.....

212 hits

Summary: In this present work, a sensitive electrocatalytic modified electrode based on 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP)/multiwalled carbon nanotubes (MWCNT) modified carbon paste electrode (CPE) was successfully developed. Electrochemical impedance spectroscopy, square wave voltammetry, chronocoulometry and cyclic voltammetry were used in prompt to evaluate the PMBP/MWCNT/CPE electrochemical capacity in detecting acetaminophen (APAP) in 0.1 M PBS pH 6.4. Under optimized conditions, PMBP/MWCNT/CPE displayed a well-defined electrocatalytic activity towards APAP oxidation in the linear responses which range from 1 _M to 1 mM (R2 = 0.991) with the LOD obtained at 0.245 _M while LOQ 0.816 _M. The presence of excess (10-fold and 25-fold) interferents such as sucrose, fructose, glucose, sodium chloride, sodium sulphate, potassium nitrate, lysine, potassium chloride and magnesium chloride as interferents was insignificant. The results presented in this study provide new perspec.....

145 hits

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 _M with limit of detection (LOD) and quantification (LOQ) at 0.1 and 0.34 _M, respectively. HPMmFBP/MWCNT/CPE exhibit good antiinterference ability, reproducibility, repeatability, and stability .....

149 hits