Displaying publications 1 - 20 of 75 in total

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  1. Validation of high performance liquid chromatography-electrochemical detection methods with simultaneous extraction procedure for the determination of artesunate, dihydroartemisinin, amodiaquine and desethylamodiaquine in human plasma for application in clinical pharmacological studies of artesunate-amodiaquine drug combination
    Lai CS, Nair NK, Muniandy A, Mansor SM, Olliaro PL, Navaratnam V
    J Chromatogr B Analyt Technol Biomed Life Sci, 2009 Feb 15;877(5-6):558-62.
    PMID: 19147417 DOI: 10.1016/j.jchromb.2008.12.037
    With the expanded use of the combination of artesunate (AS) and amodiaquine (AQ) for the treatment of falciparum malaria and the abundance of products on the market, comes the need for rapid and reliable bioanalytical methods for the determination of the parent compounds and their metabolites. While the existing methods were developed for the determination of either AS or AQ in biological fluids, the current validated method allows simultaneous extraction and determination of AS and AQ in human plasma. Extraction is carried out on Supelclean LC-18 extraction cartridges where AS, its metabolite dihydroartemisinin (DHA) and the internal standard artemisinin (QHS) are separated from AQ, its metabolite desethylamodiaquine (DeAQ) and the internal standard, an isobutyl analogue of desethylamodiaquine (IB-DeAQ). AS, DHA and QHS are then analysed using Hypersil C4 column with acetonitrile-acetic acid (0.05M adjusted to pH 5.2 with 1.00M NaOH) (42:58, v/v) as mobile phase at flow rate 1.50ml/min. The analytes are detected with an electrochemical detector operating in the reductive mode. Chromatography of AQ, DeAQ and IB-DeAQ is carried out on an Inertsil C4 column with acetonitrile-KH(2)PO(4) (pH 4.0, 0.05M) (11:89, v/v) as mobile phase at flow rate 1.00ml/min. The analytes are detected by an electrochemical detector operating in the oxidative mode. The recoveries of AS, DHA, AQ and DeAQ vary between 79.1% and 104.0% over the concentration range of 50-1400ng/ml plasma. The accuracies of the determination of all the analytes are 96.8-103.9%, while the variation for within-day and day-to-day analysis are <15%. The lower limit of quantification for all the analytes is 20ng/ml and limit of detection is 8ng/ml. The method is sensitive, selective, accurate, reproducible and suited particularly for pharmacokinetic study of AS-AQ drug combination and can also be used to compare the bioavailability of different formulations, including a fixed-dose AS-AQ co-formulation.
    Matched MeSH terms: Electrochemistry/methods*
  2. Ultrasonic synthesis of CuO nanoflakes: A robust electrochemical scaffold for the sensitive detection of phenolic hazard in water and pharmaceutical samples
    Hwa KY, Karuppaiah P, Gowthaman NSK, Balakumar V, Shankar S, Lim HN
    Ultrason Sonochem, 2019 Nov;58:104649.
    PMID: 31450344 DOI: 10.1016/j.ultsonch.2019.104649
    Hydroquinone (HQ), a phenolic compound is expansively used in many industrial applications and due to the utilization of HQ, water pollution tragedies frequently found by the improper handling and accidental outflows. When HQ is adsorbed directly through the skin that create toxic effects to human by affecting kidney, liver, lungs, and urinary tract and hence, a highly selective and sensitive technique is required for its quantification. Herein, we have developed the ultrasonic synthesis of copper oxide nanoflakes (CuO-NFs) using ultrasonic bath (20 kHz, 100 W) and successfully employed for the sensitive detection of the environmental hazardous pollutant HQ. The formed CuO-NFs were confirmed by X-ray diffraction, field emission scanning electron microscopy (FE-SEM), FT-IR spectroscopy and UV-visible spectroscopy and fabricated with the screen-printed carbon electrode (SPCE). The SEM images exhibited the uniform CuO-NFs with an average width of 85 nm. The linker-free CuO-NFs fabricated electrode showed the appropriate wide range of concentrations from 0.1 to 1400 µM and the limit of detection was found to be 10.4 nM towards HQ. The fabricated sensor having long term stability and sensitivity was successfully applied for the environmental and commercial real sample analysis and exhibited good recovery percentage, implying that the SPCE/CuO-NFs is an economically viable and benign robust scaffold for the determination of HQ.
    Matched MeSH terms: Electrochemistry/instrumentation*
  3. Trends in the use of Fenton, electro-Fenton and photo-Fenton for the treatment of landfill leachate
    Umar M, Aziz HA, Yusoff MS
    Waste Manag, 2010 Nov;30(11):2113-21.
    PMID: 20675113 DOI: 10.1016/j.wasman.2010.07.003
    Advanced oxidation processes (AOPs) such as Fenton, electro-Fenton and photo-Fenton have been applied effectively to remove refractory organics from landfill leachate. The Fenton reaction is based on the addition of hydrogen peroxide to the wastewater or leachate in the presence of ferrous salt as a catalyst. The use of this technique has proved to be one of the best compromises for landfill leachate treatment because of its environmental and economical advantages. Fenton process has been used successfully to mineralize wide range of organic constituents present in landfill leachate particularly those recalcitrant to biological degradation. The present study reviews the use of Fenton and related processes in terms of their increased application to landfill leachate. The effects of various operating parameters and their optimum ranges for maximum COD and color removal are reviewed with the conclusion that the Fenton and related processes are effective and competitive with other technologies for degradation of both raw and pre-treated landfill leachate.
    Matched MeSH terms: Electrochemistry/methods
  4. TiO₂ nanoparticle transport and retention through saturated limestone porous media under various ionic strength conditions
    Esfandyari Bayat A, Junin R, Derahman MN, Samad AA
    Chemosphere, 2015 Sep;134:7-15.
    PMID: 25889359 DOI: 10.1016/j.chemosphere.2015.03.052
    The impact of ionic strength (from 0.003 to 500mM) and salt type (NaCl vs MgCl2) on transport and retention of titanium dioxide (TiO2) nanoparticles (NPs) in saturated limestone porous media was systematically studied. Vertical columns were packed with limestone grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolent-visible spectrometry. Presence of NaCl and MgCl2 in the suspensions were found to have a significant influence on the electrokinetic properties of the NP aggregates and limestone grains. In NaCl and MgCl2 solutions, the deposition rates of the TiO2-NP aggregates were enhanced with the increase in ionic strength, a trend consistent with traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Furthermore, the NP aggregates retention increased in the porous media with ionic strength. The presence of salts also caused a considerable delay in the NPs breakthrough time. MgCl2 as compared to NaCl was found to be more effective agent for the deposition and retention of TiO2-NPs. The experimental results followed closely the general trends predicted by the filtration and DLVO calculations. Overall, it was found that TiO2-NP mobility in the limestone porous media depends on ionic strength and salt type.
    Matched MeSH terms: Electrochemistry
  5. The fate of prazosin and levonorgestrel after electrochemical degradation process: Monitoring by-products using LC-TOF/MS
    Al-Qaim FF, Mussa ZH, Yuzir A, Latip J, Othman MR
    J Environ Sci (China), 2018 Dec;74:134-146.
    PMID: 30340667 DOI: 10.1016/j.jes.2018.02.019
    Prazosin (PRZ) and levonorgestrel (LNG) are widely used as an anti-disease drugs due to their biological activity in the human body. The frequent detection of these compounds in water samples requires alternative technologies for the removal of both compounds. After electrochemical degradation of PRZ and LNG, the parent compounds could be completely removed after treatment, but the identification and characterization of by-products are necessary as well. In this study, the effects of NaCl concentration and applied voltage were investigated during the electrochemical degradation process. The results revealed that the increase of NaCl concentration and applied voltage could promote the generation of hypochlorite OCl- and then enhance the degradation of PRZ and LNG. After initial study, 6V and 0.2g NaCl were selected for further experiments (96% and 99% removal of PRZ and LNG after 40min, respectively). Energy consumption was also evaluated and calculated for PRZ and LNG at 3, 6 and 8V. Solid phase extraction (SPE) method plays an important role in enhancing the detection limit of by-products. Furthermore, characterization and identification of chlorinated and non-chlorinated by-products were conducted using an accurate liquid chromatography-time of flight/mass spectrometry LC-TOF/MS instrument. The monitoring of products during the electrochemical degradation process was performed at 6V and 0.2g NaCl in a 50mL solution. The results indicated that two chlorinated products were formed during the electrochemical process. The toxicity of by-products toward E. coli bacteria was investigated at 37°C and 20hr incubation time.
    Matched MeSH terms: Electrochemistry
  6. The electrochemical behaviour of ferrocene in a photocurable poly(methyl methacrylate-co-2-hydroxylethyl methacrylate) film for a glucose biosensor
    Bean LS, Heng LY, Yamin BM, Ahmad M
    Bioelectrochemistry, 2005 Feb;65(2):157-62.
    PMID: 15713567
    A single-step fabrication of a glucose biosensor with simultaneous immobilization of both ferrocene mediator and glucose oxidase in a photocurable methacrylic film consisting of poly(methyl methacrylate-co-2-hydroxylethyl methacrylate) was reported. The entrapped ferrocene showed reversible redox behaviour in the photocured film and no significant leaching of both entrapped ferrocene and enzyme glucose oxidase was observed because of the low water absorption properties of the co-polymer films. From electrochemical studies, ferrocene entrapped in the co-polymer film demonstrated slow diffusion properties. A linear glucose response range of 2-11 mM was obtained at low applied potential of +0.25 V. The glucose biosensor fabricated by this photocuring method yielded sensor reproducibility and repeatability with relative standard deviation of <10% and long-term stability of up to 14 days. The main advantage of the use of photocurable procedure is that biosensor membrane fabrication can be performed in a single step without any lengthy chemical immobilization of enzyme.
    Matched MeSH terms: Electrochemistry*
  7. Fulltext The effects of printing orientation on the electrochemical behaviour of 3D printed acrylonitrile butadiene styrene (ABS)/carbon black electrodes
    Bin Hamzah HH, Keattch O, Covill D, Patel BA
    Sci Rep, 2018 Jun 14;8(1):9135.
    PMID: 29904165 DOI: 10.1038/s41598-018-27188-5
    Additive manufacturing also known as 3D printing is being utilised in electrochemistry to reproducibly develop complex geometries with conductive properties. In this study, we explored if the electrochemical behavior of 3D printed acrylonitrile butadiene styrene (ABS)/carbon black electrodes was influenced by printing direction. The electrodes were printed in both horizontal and vertical directions. The horizsontal direction resulted in a smooth surface (HPSS electrode) and a comparatively rougher surface (HPRS electrode) surface. Electrodes were characterized using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. For various redox couples, the vertical printed (VP) electrode showed enhanced current response when compared the two electrode surfaces generated by horizontal print direction. No differences in the capacitive response was observed, indicating that the conductive surface area of all types of electrodes were identical. The VP electrode had reduced charge transfer resistance and uncompensated solution resistance when compared to the HPSS and HPRS electrodes. Overall, electrodes printed in a vertical direction provide enhanced electrochemical performance and our study indicates that print orientation is a key factor that can be used to enhance sensor performance.
    Matched MeSH terms: Electrochemistry
  8. The effect of morphine on the biosynthesis of catecholamines in the rat brain
    Malini M, Kwan TK, Perumal R
    Biochem. Mol. Biol. Int., 1994 Feb;32(2):279-90.
    PMID: 8019433
    In vivo studies involved monitoring the effect of morphine administration on catecholamine biosynthesis by the brain while in vitro studies involved studying the effect of morphine on the uptake of tritiated tyrosine by synaptosomes and its subsequent incorporation into the catecholamines. The extremely low levels of these endogenous compounds required the use of High Performance Liquid Chromatography with electrochemical detection. Intra-peritoneal injection of morphine at a dosage of 10 mg/kg did not produce appreciable changes in the catecholamine levels but a dosage of 30 mg/kg morphine was found to elevate dihydroxy phenylacetic acid content. At a dosage of 60 mg/kg, dopamine levels were elevated while noradrenaline was depleted. Morphine, at a concentration of 1 x 10(-5)M increases the incorporation of tritiated tyrosine into dopamine and dihydroxy phenylacetic acid in synaptosomal preparations.
    Matched MeSH terms: Electrochemistry
  9. The biocathode of microbial electrochemical systems and microbially-influenced corrosion
    Kim BH, Lim SS, Daud WR, Gadd GM, Chang IS
    Bioresour Technol, 2015 Aug;190:395-401.
    PMID: 25976915 DOI: 10.1016/j.biortech.2015.04.084
    The cathode reaction is one of the most important limiting factors in bioelectrochemical systems even with precious metal catalysts. Since aerobic bacteria have a much higher affinity for oxygen than any known abiotic cathode catalysts, the performance of a microbial fuel cell can be improved through the use of electrochemically-active oxygen-reducing bacteria acting as the cathode catalyst. These consume electrons available from the electrode to reduce the electron acceptors present, probably conserving energy for growth. Anaerobic bacteria reduce protons to hydrogen in microbial electrolysis cells (MECs). These aerobic and anaerobic bacterial activities resemble those catalyzing microbially-influenced corrosion (MIC). Sulfate-reducing bacteria and homoacetogens have been identified in MEC biocathodes. For sustainable operation, microbes in a biocathode should conserve energy during such electron-consuming reactions probably by similar mechanisms as those occurring in MIC. A novel hypothesis is proposed here which explains how energy can be conserved by microbes in MEC biocathodes.
    Matched MeSH terms: Electrochemistry/instrumentation*
  10. Fulltext Synthesis, characterization, and performance evaluation of multilayered photoanodes by introducing mesoporous carbon and TiO2 for humic acid adsorption
    Hosseini S, Jahangirian H, Webster TJ, Soltani SM, Aroua MK
    Int J Nanomedicine, 2016;11:3969-78.
    PMID: 27574426 DOI: 10.2147/IJN.S96558
    Nanostructured photoanodes were prepared via a novel combination of titanium dioxide (TiO2) nanoparticles and mesoporous carbon (C). Four different photoanodes were synthesized by sol-gel spin coating onto a glassy substrate of fluorine-doped tin oxide. The photocatalytic activities of TiO2, TiO2/C/TiO2, TiO2/C/C/TiO2, and TiO2/C/TiO2/C/TiO2 photoanodes were evaluated by exposing the synthesized photoanodes to UV-visible light. The photocurrent density observed in these photoanodes confirmed that an additional layer of mesoporous carbon could successfully increase the photocurrent density. The highest photocurrent density of ~1.022 mA cm(-2) at 1 V/saturated calomel electrode was achieved with TiO2/C/C/TiO2 under an illumination intensity of 100 mW cm(-2) from a solar simulator. The highest value of surface roughness was measured for a TiO2/C/C/TiO2 combination owing to the presence of two continuous layers of mesoporous carbon. The resulting films had a thickness ranging from 1.605 µm to 5.165 µm after the calcination process. The presence of double-layer mesoporous carbon resulted in a 20% increase in the photocurrent density compared with the TiO2/C/TiO2 combination when only a single mesoporous carbon layer was employed. The improved performance of these photoanodes can be attributed to the enhanced porosity and increased void space due to the presence of mesoporous carbon. For the first time, it has been demonstrated here that the photoelectrochemical performance of TiO2 can be improved by integrating several layers of mesoporous carbon. Comparison of the rate of removal of humic acid by the prepared photoanodes showed that the highest performance from TiO2/C/C/TiO2 was due to the highest photocurrent density generated. Therefore, this study showed that optimizing the sequence of mesoporous carbon layers can be a viable and inexpensive method for enhanced humic acid removal.
    Matched MeSH terms: Electrochemistry
  11. Synthesis and characterization of cellulose and hydroxyapatite-carbon electrode composite for trace plumbum ions detection and its validation in blood serum
    Ajab H, Dennis JO, Abdullah MA
    Int J Biol Macromol, 2018 Jul 01;113:376-385.
    PMID: 29486259 DOI: 10.1016/j.ijbiomac.2018.02.133
    A novel synthesis and characterization of cellulose, hydroxyapatite and chemically-modified carbon electrode (Cellulose-HAp-CME) composite was reported for the analysis of trace Pb(II) ions detection and its validation in blood serum. The Field Emission Scanning Electron Microscopy (FESEM) analyses showed that the composite retained the orderly porous structure but with scattered particle size agglomeration. The Fourier Transform Infrared Spectroscopy (FTIR) spectra suggested the presence of functional groups associated with the bending and stretching of carbon bonds and intermolecular H-bonding. X-ray Diffraction (XRD) analyses further elucidated that the crystallite size could have influenced the properties of the electrode. Based on Thermo-gravimetric Analysis (TGA/DTG), the composites showed thermal stability with more than 60% residual content at 700°C. The sensor was successfully developed for trace Pb(II) ions detection in complex medium such as blood serum, in the physiologically relevant range of 10-60ppb, with resulting Limit of Detection (LOD) of 0.11±0.36ppb and Limit of Quantification (LOQ) of 0.36±0.36ppb. The newly fabricated electrode could be advantageous as a sensing platform with favourable electrochemical characteristics for robust, in situ and rapid environmental and clinical analyses of heavy metal ions.
    Matched MeSH terms: Electrochemistry
  12. Fulltext Sudomotor dysfunction independently predicts incident cardiovascular-renal events and all-cause death in type 2 diabetes: the Joint Asia Diabetes Evaluation register
    Lim LL, Fu AWC, Lau ESH, Ozaki R, Cheung KKT, Ma RCW, et al.
    Nephrol Dial Transplant, 2019 Aug 01;34(8):1320-1328.
    PMID: 29939305 DOI: 10.1093/ndt/gfy154
    BACKGROUND: Early detection and risk factor control prevent chronic kidney disease (CKD) progression. Evaluation of peripheral autonomic dysfunction may detect incident cardiovascular-renal events in type 2 diabetes (T2D).

    METHODS: SUDOSCAN, a non-invasive tool, provides an age-adjusted electrochemical skin conductance (ESC) composite score incorporating hands/feet ESC measurements, with a score ≤53 indicating sudomotor dysfunction. A consecutive cohort of 2833 Chinese adults underwent structured diabetes assessment in 2012-13; 2028 participants without preexisting cardiovascular disease (CVD) and CKD were monitored for incident cardiovascular-renal events until 2015.

    RESULTS: In this prospective cohort {mean age 57.0 [standard deviation (SD) 10.0] years; median T2D duration 7.0 [interquartile range (IQR) 3.0-13.0] years; 56.1% men; 72.5% never-smokers; baseline ESC composite score 60.7 (SD 14.5)}, 163 (8.0%) and 25 (1.2%) participants developed incident CKD and CVD, respectively, after 2.3 years of follow-up. The adjusted hazard ratios (aHRs) per 1-unit decrease in the ESC composite score for incident CKD, CVD and all-cause death were 1.02 [95% confidence interval (CI) 1.01-1.04], 1.04 (1.00-1.07) and 1.04 (1.00-1.08), respectively. Compared with participants with an ESC composite score >53, those with a score ≤53 had an aHR of 1.56 (95% CI 1.09-2.23) for CKD and 3.11 (95% CI 1.27-7.62) for CVD, independent of common risk markers. When added to clinical variables (sex and duration of diabetes), the ESC composite score improved discrimination of all outcomes with appropriate reclassification of CKD risk.

    CONCLUSIONS: A low ESC composite score independently predicts incident cardiovascular-renal events and death in T2D, which may improve the screening strategy for early intervention.

    Matched MeSH terms: Electrochemistry
  13. Fulltext Structural, Impedance, and EDLC Characteristics of Proton Conducting Chitosan-Based Polymer Blend Electrolytes with High Electrochemical Stability
    Aziz SB, Abdulwahid RT, Hamsan MH, Brza MA, Abdullah RM, Kadir MFZ, et al.
    Molecules, 2019 Sep 27;24(19).
    PMID: 31569650 DOI: 10.3390/molecules24193508
    In this report, a facile solution casting technique was used to fabricate polymer blend electrolytes of chitosan (CS):poly (ethylene oxide) (PEO):NH4SCN with high electrochemical stability (2.43V). Fourier transform infrared (FTIR) spectroscopy was used to investigate the polymer electrolyte formation. For the electrochemical property analysis, cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) techniques were carried out. Referring to the FTIR spectra, a complex formation between the added salt and CS:PEO was deduced by considering the decreasing and shifting of FTIR bands intensity in terms of functional groups. The CS:PEO:NH4SCN electrolyte was found to be electrochemically stable as the applied voltage linearly swept up to 2.43V. The cyclic voltammogram has presented a wide potential window without showing any sign of redox peaks on the electrode surface. The proved mechanisms of charge storage in these fabricated systems were found to be double layer charging. The EIS analysis showed the existence of bulk resistance, wherein the semicircle diameter decreased with increasing salt concentration. The calculated maximum DC conductivity value was observed to be 2.11 × 10-4 S/cm for CS:PEO incorporated with 40 wt% of NH4SCN salt. The charged species in CS:PEO:NH4SCN electrolytes were considered to be predominantly ionic in nature. This was verified from transference number analysis (TNM), in which ion and electron transference numbers were found to be tion = 0.954 and tel = 0.045, respectively. The results obtained for both ion transference number and DC conductivity implied the possibility of fabricating electrolytes for electrochemical double layer capacitor (EDLC) device application. The specific capacitance of the fabricated EDLC was obtained from the area under the curve of the CV plot.
    Matched MeSH terms: Electrochemistry*
  14. Fulltext SnO2/Pt thin film laser ablated gas sensor array
    Shahrokh Abadi MH, Hamidon MN, Shaari AH, Abdullah N, Wagiran R
    Sensors (Basel), 2011;11(8):7724-35.
    PMID: 22164041 DOI: 10.3390/s110807724
    A gas sensor array was developed in a 10 × 10 mm(2) space using Screen Printing and Pulse Laser Ablation Deposition (PLAD) techniques. Heater, electrode, and an insulator interlayer were printed using the screen printing method on an alumina substrate, while tin oxide and platinum films, as sensing and catalyst layers, were deposited on the electrode at room temperature using the PLAD method, respectively. To ablate SnO(2) and Pt targets, depositions were achieved by using a 1,064 nm Nd-YAG laser, with a power of 0.7 J/s, at different deposition times of 2, 5 and 10 min, in an atmosphere containing 0.04 mbar (4 kPa) of O(2). A range of spectroscopic diffraction and real space imaging techniques, SEM, EDX, XRD, and AFM were used in order to characterize the surface morphology, structure, and composition of the films. Measurement on the array shows sensitivity to some solvent and wood smoke can be achieved with short response and recovery times.
    Matched MeSH terms: Electrochemistry/methods
  15. Sequential nitrification and denitrification in a novel palm shell granular activated carbon twin-chamber upflow bio-electrochemical reactor for treating ammonium-rich wastewater
    Mousavi S, Ibrahim S, Aroua MK
    Bioresour Technol, 2012 Dec;125:256-66.
    PMID: 23026342 DOI: 10.1016/j.biortech.2012.08.075
    In this study, a twin-chamber upflow bio-electrochemical reactor packed with palm shell granular activated carbon as biocarrier and third electrode was used for sequential nitrification and denitrification of nitrogen-rich wastewater under different operating conditions. The experiments were performed at a constant pH value for the denitrification compartment. The effect of variables, namely, electric current (I) and hydraulic retention time (HRT), on the pH was considered in the nitrification chamber. The response surface methodology was used based on three levels to develop empirical models for the study on the effects of HRT and current values as independent operating variables on NH(4)(+)-N removal. The results showed that ammonium was reduced within the function of an extensive operational range of electric intensity (20-50 mA) and HRT (6-24h). The optimum condition for ammonium oxidation (90%) was determined with an I of 32 mA and HRT of 19.2h.
    Matched MeSH terms: Electrochemistry/instrumentation*
  16. Sequential flow injection determination of chlorine species using a triiodide-selective electrode detector
    Saad B, Wai WT, Ali AS, Saleh MI
    Anal Sci, 2006 Jan;22(1):45-50.
    PMID: 16429771
    A flow injection analysis (FIA) method for the determination of four residual chlorine species, namely combined available chlorine (CAC), free available chlorine (FAC), total available chlorine (TAC) and chlorite (ClO2-) was developed using a flow-through triiodide-selective electrode as a detector. An important strategy of speciation studies utilized the kinetic discrimination of reactions between the CAC and FAC with Fe2+, which was applied to the speciation of FAC, CAC and TAC. The speciation of available chlorine species and chlorite (an oxychlorine species) was achieved by using the same set-up, but using flow streams of different pH. The effects of the pH of the carrier stream, the flow rate and the sample volume were studied. The method exhibited linearity from 2.8 x 10(-6) to 2.8 x 10(-4) M active chlorine (expressed as OCl-) with a detection limit of 1.4 x 10(-6) M. The selectivity of the method was studied by examining the minimum pH for the oxidation of iodide by other oxidants, and also by assessing the potentiometric selectivity coefficients. The proposed method was successfully applied to the determination of chlorine species in tap water, and disinfecting formulations where good agreement occurred between the proposed and standard methods were found.
    Matched MeSH terms: Electrochemistry/instrumentation; Electrochemistry/methods
  17. Separators used in microbial electrochemical technologies: Current status and future prospects
    Daud SM, Kim BH, Ghasemi M, Daud WR
    Bioresour Technol, 2015 Nov;195:170-9.
    PMID: 26141668 DOI: 10.1016/j.biortech.2015.06.105
    Microbial electrochemical technologies (METs) are emerging green processes producing useful products from renewable sources without causing environmental pollution and treating wastes. The separator, an important part of METs that greatly affects the latter's performance, is commonly made of Nafion proton exchange membrane (PEM). However, many problems have been identified associated with the Nafion PEM such as high cost of membrane, significant oxygen and substrate crossovers, and transport of cations other than protons protons and biofouling. A variety of materials have been offered as alternative separators such as ion-exchange membranes, salt bridges, glass fibers, composite membranes and porous materials. It has been claimed that low cost porous materials perform better than PEM. These include J-cloth, nylon filter, glass fiber mat, non-woven cloth, earthen pot and ceramics that enable non-ion selective charge transfer. This paper provides an up-to-date review on porous separators and plots directions for future studies.
    Matched MeSH terms: Electrochemistry/instrumentation*; Electrochemistry/trends*
  18. Reduction of hexavalent chromium using Aerva lanata L.: elucidation of reduction mechanism and identification of active principles
    Poonkuzhali K, Rajeswari V, Saravanakumar T, Viswanathamurthi P, Park SM, Govarthanan M, et al.
    J Hazard Mater, 2014 May 15;272:89-95.
    PMID: 24681590 DOI: 10.1016/j.jhazmat.2014.03.001
    The effluent discharge treatment for controlling the environment from non biodegradable metal contaminants using plant extract is an efficient technique. The reduction of hexavalent chromium by abundantly available weed, Aerva lanata L. was investigated using batch equilibrium technique. The variables studied were Cr(VI) concentration, Aerva lanata L. dose, contact time, pH, temperature and agitation speed. Cyclic voltammetry and ICP-MS analysis confirmed the reduction of Cr(VI) to Cr(III). Electrochemical analysis proved that, the chromium has not been degraded and the valency of the chromium has only been changed. ICP-MS analysis shows that 100ng/L of hexavalent chromium was reduced to 97.01ng/L trivalent chromium. These results suggest that components present in the Aerva lanata L. are responsible for the reduction of Cr(VI) to Cr(III). The prime components ferulic acid, kaempherol and β-carboline present in the Aerva lanata L. may be responsible for the reduction of Cr(VI) as evident from LC-MS analysis.
    Matched MeSH terms: Electrochemistry
  19. Redox equilibria of iron oxides in aqueous-based magnetite dispersions: effect of pH and redox potential
    Pang SC, Chin SF, Anderson MA
    J Colloid Interface Sci, 2007 Jul 1;311(1):94-101.
    PMID: 17395194
    The effect of pH and redox potential on the redox equilibria of iron oxides in aqueous-based magnetite dispersions was investigated. The ionic activities of each dissolved iron species in equilibrium with magnetite nanoparticles were determined and contoured within the Eh-pH framework of a composite stability diagram. Both standard redox potentials and equilibrium constants for all major iron oxide redox equilibria in magnetite dispersions were found to differ from values reported for noncolloidal systems. The "triple point" position of redox equilibrium among Fe(II) ions, magnetite, and hematite shifted to a higher standard redox potential and an equilibrium constant which was several orders of magnitude higher. The predominant area of magnetite stability was enlarged to cover a wider range of both pH and redox potentials as compared to that of a noncolloidal magnetite system.
    Matched MeSH terms: Electrochemistry
  20. Recent uses of carbon nanotubes & gold nanoparticles in electrochemistry with application in biosensing: A review
    Alim S, Vejayan J, Yusoff MM, Kafi AKM
    Biosens Bioelectron, 2018 Dec 15;121:125-136.
    PMID: 30205246 DOI: 10.1016/j.bios.2018.08.051
    The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and conceivable outcomes to the headway of new era devices utilized as a part of biosensing. The focused on the quick and legitimate detecting of specific biomolecules using functionalized gold nanoparticles (Au NPs), and carbon nanotubes (CNTs) has turned into a noteworthy research enthusiasm for the most recent decade. Sensors created with gold nanoparticles or carbon nanotubes or in some cases by utilizing both are relied upon to change the very establishments of detecting and distinguishing various analytes. In this review, we will examine the current utilization of functionalized AuNPs and CNTs with other synthetic mixes for the creation of biosensor prompting to the location of particular analytes with low discovery cutoff and quick reaction.
    Matched MeSH terms: Electrochemistry/trends*
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