Penentuan Plumbum Menggunakan Kaedah Analisis Suntikan Aliran Berdasarkan Pembentukan Kompleks antara Plumbum dengan Reagen Galosianin

Flow injection analysis (FIA) with UV-Visible detection has been used in this study for Pb(II) detection in an aqueous environment. The FIA system used in this study was based on the reaction between Pb (II) and gallocyanine which formed a complex with maximum absorbance at around 550 nm. The carrier solution flow rate, solution pH and the reagent concentration have been optimised to increase the efficiency of the FIA system. The FIA system was found to be optimum at 1.2 mL/min flow rate and pH 8. The dynamic range for the Pb(II) concentration was found to be between 1.0 x 1([3 mg/L and 1.0 x lOt mg/L. The reproducibility of the method was very good with RSD value of 1.03 %. At mole ratio of 1:1, Cd(II) , Ni(II) and Co(II) were found to interfere with respective relative error of 10.05 %, 10.15 % and 10.25 %

Development of a flow-through optosensor for determination of Co(II)

A flow-through optical fibre chemical sensor for the determination of Co(II) at trace level using immobilised 2-(4-pyridylazo)resorcinol (PAR) as the reagent phase is proposed. PAR is physically adsorbed onto XAD-7. This method provided a great sensitivity and simplicity with wide linear response range from 1 × 10−2 to 1 × 103 ppm and detection limit of 20 ppb. This method also showed a reproducible result with relative standard deviation (R.S.D.) of 1.78% and response time of 5 min. The response towards Co(II) was also reversible using acidified KCl as the regenerating solution. Interference studies showed that Cr(III) significantly interfered during the determination. Excellent agreement with reference to inductively coupled plasma optical emission spectroscopy (ICPOES) method was achieved when the developed sensor was applied for determination of Co(II) in aqueous samples

Spectrophotometric determination of trace Arsenic (III) ion based on complex formation with gallocyanine

In this study, a simple, selective and sensitive method, for spectrophotometric determination of As(III) with gallocyanine as the sensitive reagent was developed. The wavelength of an analytical measurement, for the determination of As (III), using gallocyanine was at 630nm with an optimum response at pH 2. The RSD for the reproducibility of 100 ppm As(III) was 2.3%. The LOD was 0.04 ppm with linear dynamic range in As(III) concentration of 0.2 - 1.5 ppm. The developed method has been validated against Atomic AbsorptionSpectrophotometry (AAS). The interference study of several metal ions was carried out andit revealed that that Mn (II) ion was interfered the most

Development of optical test strip for rapid determination of trace arsenic using immobilized gallocyanine

Irreversible test strip for the determination of arsenic has been developed. It has a rectangular sensing zone containing all the reagents necessary to produce a selective response to arsenic and formed by immobilized gallocyanine inside chitosan membrane. This method offer sensitivity and simplicity in detecting arsenic as no prior treatment or extraction is required. A linear response was attained in the arsenic concentration in the range of 10 to 30 ppm with calculated limit of detection of 0.96 ppm. This method also showed a reproducible result with relative standard deviation (RSD) of 0.87% and response time of ~5min. Interference studies showed that Pb(II) and Ni(II) significantly interfered during the determination. The developed sensor has been validated against Atomic Absorption Spectroscopy method and proven comparable

Microfluidics-based lab-on-chip systems in DNA-based biosensing: An overview.

Microfluidics-based lab-on-chip (LOC) systems are an active research area that is revolutionising high-throughput sequencing for the fast, sensitive and accurate detection of a variety of pathogens. LOCs also serve as portable diagnostic tools. The devices provide optimum control of nanolitre volumes of fluids and integrate various bioassay operations that allow the devices to rapidly sense pathogenic threat agents for environmental monitoring. LOC systems, such as microfluidic biochips, offer advantages compared to conventional identification procedures that are tedious, expensive and time consuming. This paper aims to provide a broad overview of the need for devices that are easy to operate, sensitive, fast, portable and sufficiently reliable to be used as complementary tools for the control of pathogenic agents that damage the environment

Electrochemical characteristic of Biotinyl Somatostatin- 14/Nafion modified gold electrode in development of sensor for determination of Hg(II)

Electrochemical sensor for Hg(II) has been developed using Biotinyl Somatostatin-14 peptide modified gold electrode utilizing nafion as the immobilizing agent. Experimental conditions such as pH, supporting electrolyte and scan rate were optimized. Detection of mercury using Biotinyl Somatostatin-14 peptide/Nafion has been observed to be optimum under acidic conditions. Good relative standard deviation of 3.7% has been obtained indicating reliability of the detection system. A linear calibration plot in the range of 40-170 µgL-1 was obtained with sensitivity value of 1×10-10 AµM-1. Limit of detection (LOD) obtained is 0.4 µgL-1 which is below the WHO guidelines for drinking water. The scan rate study showed that the process is a complex surface process, mostly involving an adsorption process. This developed method was applied for determination of Hg(II) in actual waste water samples and a good agreement was obtained between the proposed method and ICP-MS based on the analysis of the waste water samples

Laboratory diagnosis and potential application of nucleic acid biosensor approach for early detection of dengue virus infections

Dengue fever is caused by the dengue virus, the genus of Flaviviridae virus family. Until now, there is no specific medication to kill the dengue virus and patients just solely depend on the treatment of the dengue infection symptoms. Thus, a highly sensitive and rapid diagnostic tool for early diagnosis of dengue virus is very desirable, especially in resource limited-condition. We briefly review pro and cons of existing diagnostic methods for the detection of dengue virus (virus isolation, PCR, NS1Ag, Serology). We also highlight the recent advances of the biosensor technology in the dengue diagnostic dengue as a promising point-of-care diagnostic in the future. The DNA based biosensor technology combined miniaturized sample preparation offers a good opportunity for the commercialized point of care testing for dengue diagnosis in the future

Voltammetric studies of nano zirconium dioxide/carbon nanotubes/chitosan-modified glassy carbon electrodes.

Voltammetric studies of a sensitive electrochemical DNA sensor based on ZrO2 nanoparticles and multi-walled carbon nanotube (MWNTs) for DNA immobilization is described. Layer deposition technique was used to prepare nano ZrO2/MWNTs/chitosan-modified glassy carbon electrode (GCE) and oligonucleotides were immobilized to the GCE. The immobilization of DNA on the electrode was monitored by cyclic voltammetry (CV) analysis by measuring the change of peak currents using electroactive methylene blue (MB) as an indicator. Compared with previous DNA sensor with oligonucleotides directly incorporated on carbon electrodes, this carbon nanotubes-based assay with its large surface area and good charge-transport characteristics increased DNA attachment quantity. Parameters used on this study including electrochemical characterization, scan rate study, pH optimization, and scanning electron microscope (SEM) as well as chronoamperometry (CA) and chronocoulometry (CC). The electrochemical reduction and oxidation of the redox couples of methylene blue (as a DNA indicator) can be recognized easily by the solid-phase voltammetry of microparticles. The cyclic voltammograms for three differently modified electrodes, nano ZrO2/chitosan, MWNTs/chitosan and nano ZrO2/MWNTs/chitosan, showed 2 major peaks responding to redox couple of methylene blue. INTRODUCTIO

Generalised additive model of DIR based on region, monsoon and state in Peninsular Malaysia

A generalised additive model (GAM) framework for dengue incidence rate (DIR) as a response in Peninsular Malaysia for three areas which as region, monsoon and state has been adopted in this study. A spatio-temporal series of 1296 observations with the following explanatory variables; state, latitude and longitude of state capital, land area of state, year, month, total dengue cases, estimated state population pertaining to the year, population density of state, maximum, minimum and average monthly rainfall, maximum, minimum and average monthly temperature, monthly number of rainy days and Nino 4. Result presents three basis model with statistically significant explanatory variables consist of mean rainfall (current month and lag 3-month), mean temperature (current month and lag 1-month), number of rainy day (current month and lag 3-month), Nino 4 (lag 6-month), DIR (lag 3-month) and interaction between temperature lag 1-month and Nino 4 (lag 6-month), population, population density, year, month, monsoon area, state and region. Model 1, Model 2 and Model 3 with the lowest deviance, AIC and BIC are the best models of DIR that successfully developed for three areas mentioned

Development of electrochemical sensor for detection of mercury by exploiting His-Phe-His-Ala-His-Phe-Ala-Phe modified electrode.

A sensitive voltammetric method for detection of mercury ions is described which is made by modifying a gold electrode with 3-mercaptopropionic acid followed by covalent attachment of the octapeptide His-Phe-His-Ala-His-Phe-Ala-Phe to the self-assembled monolayer using carbodiimide coupling. A linear working range for concentration of mercury between 0.25 to 0.81 with LOD 9.5×10 -9 M was obtained which is below the WHO guidelines for drinking water. The reproducibility of the analytical signal is 4.5% in indicating a reproducible and reliable detection system. The developed method was applied for the detection of Hg(II) in spiked wastewater and validated against ICPMS. Good agreement was obtained between the developed method and ICPMS. Insignificant interference was observed by As 3+, Cr 3+, Cu 2+, Ni 2+, Pb 2+and Zn 2+ in detection of Hg(II) thus making the developed system highly potential for electrochemical sensor in Hg(II) detection