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The results of trial experiments carried out with a computer simulation model of total reflection X‐ray fluorescence, TXRF system to determine optimum conditions for detecting certain elements of interest under various analytical conditions in a given ten‐element standard sample is presented in this paper. Results of these trial experiments show that the detectability of elements improved with increasing applied voltages up to about 43kV (for a Molybdenum anode TXRF spectrometer) and atomic number of elements. Variation of geometry such as the glancing incidence angle of the excitation beam reflected slight increase in minimum detection limit, MDL values as the angle of incidence is reduced from an optimum value of 1.6mradian to 1.0mradian. The nature of the sample support was observed to affect the detectability of the elements as good detection limits were obtained if gold is used as sample holder..

The purpose of this paper is to review the novel application of surface plasmon resonance (SPR) in sensing heavy metal ions and the development of SPR to become an alternative heavy metal ions sensor.

The possible dangerous toxic effects of heavy metal ions are revealed in the short introduction. The existing conventional methods for sensing heavy metal ions and their drawbacks are also discussed. To overcome these drawbacks, SPR has been investigated from the basic principle to the potential alternative in sensing heavy metal ions.

Application of SPR in sensing heavy metal ions emerged a decade ago. A wide range of active layers or recognition elements (e.g. polymer, protein, nanoparticles) have been developed to combine with SPR. The detection limit, sensitivity and selectivity of SPR sensing in heavy metal ions have been improved from time to time, until the present.

This paper provides up-to-date and systematic information on SPR sensing for heavy metal ions. Different advancements on active layers or recognition molecules have been discussed in detail and arranged in the order of their chronological evolution. The present review may provide researchers with valuable information regarding novel heavy metal ions sensor using SPR and encourage them to take this area for further research and development.

The purpose of this paper is to develop a sensitive and cost effective colorimetric sensor for detection of methyl parathion (MP) using simple circuitry. A simple and sensitive concept of colorimetric sensor instrument represents a rapidly expanding field of sensor techniques to monitor MP neurotoxins is described within certain conditions of producing color in samples. The variation of intensity of color with concentration provides discrimination between different concentrations of MP. The colorimetric instrument displays well‐defined signals towards hydrolyzed samples of MP.

The principle of light intensity measurement has been applied to measure various concentrations of MP based on Lambert‐Beer theory. This device and its processes are useful for quantitative analysis of MP. The detection limits were found within a range of 0.1‐1.5 ppm.

The experiments from sophisticated analytical techniques are costly and time‐consuming processes that validate the proposed system.

This paper's original proposition of using quantification of MP with colorimetric sensor instrument obtained promising results.

The colorimetric sensor instrument provides a new method for quantification of MP in unknown samples within detection limits.

This paper aims to provide a detailed review of weak interaction biosensors and several common biosensor methods for magnifying signals, as well as judiciously guide readers through selecting an appropriate detecting system and signal amplification method according to their research and application purpose.

This paper classifies the weak interactions between biomolecules, summarizes the common signal amplification methods used in biosensor design and compares the performance of different kinds of biosensors. It highlights a potential electrochemical signal amplification method: the G protein signaling cascade amplification system.

Developed biosensors which, based on various principles, have their own strengths and weaknesses have met the basic detection requirements for weak interaction between biomolecules: the selectivity, sensitivity and detection limit of biosensors have been consistently improving with the use of new signal amplification methods. However, most of the weak interaction biosensors stop at the research stage; there are only a minority realization of final commercial application.

This paper evaluates the status of research and application of weak interaction biosensors systematically. The G protein signaling cascade amplification system proposal offers a new avenue for the research and development of electrochemical biosensors.

This paper seeks to apply an improved electrometric method using polarized electrodes to quantify iodine in 241 salt samples pertaining to 15 different brands procured from the local market.Design/methodology/approach – Comparative evaluation of the method is made with the iodometric titration and the colorimetric methods.

The results obtained reveal that the electrometric method excels in attaining higher level of accuracy, precision and lower detection limit, backed by ease of operation.

The method warrants reproducible results both for replicate synthetic and market samples, with a lower detection limit of about 0.1ppm within an acceptable limit of error.

The study shows significant difference between the estimated and labelled iodine values in various brands of iodized salts. Most of the salt samples analysed contain iodine levels far exceeding the WHO permitted limit. The method has the potential of application for in‐situ iodine measurement in iodine fortified salts to ensure rapid quality control, both at the retailer and production levels.

The purpose of this work is to explore electrical properties of an electrochemical sensor designed for the detection of malachite green (MG) present in an aqueous solution.

The present sensor consists in the spatial coupling of a polymeric membrane and an ion-sensitive electrode (platinum electrode). The preparation of the polymeric membrane involves the incorporation of an ionophore (D2HPA), a polymer (polyvinylchloride [PVC]) and a plasticizer (dioctyl phthalate [DOP]). Several techniques have been used to characterize this sensor: the cyclic voltammetry, the electrochemical impedance spectroscopy and the optical microscopy. The sensibility, the selectivity and the kinetic study of a modified platinum electrode have been evaluated by cyclic voltammetry.

The obtained results reveal the possibility of a linear relationship between the current of reduction peaks and MG concentration. A linear response was obtained in a wide-concentration range that stretches from 10⁻⁵ to 10⁻¹³ mol L⁻¹, with a good correlation coefficient (0.976) and a good detection limit of 5.74 × 10⁻¹⁴ mol L⁻¹ (a signal-to-noise ratio of 3). In addition, the voltammetric response of modified electrode can be enhanced by adding a layer of Nafion membrane. Under this optimal condition, a linear relationship was obtained, with a correlation coefficient of 0.986 and a detection limit of 1.92 × 10⁻¹⁸ mol L⁻¹.

In the present research, a convenient, inexpensive and reproducible method for the detection of MG was developed. The developed sensor is capable of competing against the conventional techniques in terms of speed, stability and economy.

The purpose of this study is to prepare various CeO₂-based carbon material (CNT, CB, GO) nanocomposites through a wet chemical process for the development of a sensor probe to detect various environmental toxins by using an electrochemical approach under room temperature conditions. A comparative study on sensitive and selective phenolic sensor (4-methoxyphenol; 4-MP) has been fabricated by modifying a glassy carbon electrode (GCE) with various nanocomposites (NCs) such as CeO₂, CeO₂–CNT (carbon nanotubes), CeO₂–CB (carbon black) and CeO₂–GO (graphene oxide) NCs.

The CeO₂–CNT NCs were prepared by the wet chemical method at low temperature. NCs were characterized by various methods such as transmission electron microscopy (TEM), Fourier-transform infra-red (FTIR), ultra-violet/visible (UV-Vis) spectroscopy and XRD (X-ray diffraction). CeO₂–CNT NCs were immobilized as a film on the flat surface of the GCE by using binders (5% Nafion). The electrochemical measurements of the 4-MP detection with the CeO₂–CNT NCs/Nafion/GCE sensor were studied by the current-voltage method.

In the optimal conditions, the sensitivity, detection limit and limit of quantification of 4-MP sensor probe were found to be 47.56 µAcm-2 µM⁻¹, 12.0 ± 0.2 nM and 40.0 ± 0.5 nM (S/N of 3), respectively.

This electrochemical sensor showed an acceptable analytical performance in the detection of 4-MP with higher sensitivity, lower detection limit, large dynamic concentration range, good reproducibility and fast response time.

This electrochemical approach can be applied practically for the determination of selective 4-MP in real environmental and extracted samples.

CeO₂–CNT NCs/Nafion/GCE sensor probe was used for the safety of environmental and health-care fields at larger scales.

This electrochemical approach is a significant achievement on the development of sensor probe. The results are indicated as being technically detailed with an up-to-date account of recent chemical sensor research studies.

This paper aims to review the potential application of surface plasmon resonance (SPR) in diagnosis of dengue virus (DENV-2) E-protein and the development of SPR to become an alternative DENV sensor.

In this review, the existing standard laboratory techniques to diagnosis of DENV are discussed, together with their drawbacks. To overcome these drawbacks, SPR has been aimed to be a valuable optical biosensor for identification of antibodies to the DENV antigen. The review also includes the future studies on three-dimensional poly(amidoamine) (PAMAM) dendrimer-surface-assembled monolayer (SAM)-Au multilayer thin films, which are envisaged to have high potential sensitive and selective detection ability toward target E-proteins.

Application of SPR in diagnosis of DENV emerged over recent years. A wide range of immobilized biorecognition molecules have been developed to combine with SPR as an effective sensor. The detection limit, sensitivity and selectivity of SPR sensing in DENV have been enhanced from time to time, until the present.

The main purpose of this review is to provide authors with up-to-date and useful information on sensing DENV using SPR and to introduce a novel three-dimensional PAMAM-SAM-Au multilayer thin films for future research on SPR sensing applications.

The use of energy‐dispersive X‐ray fluorescence in the oil industries increases continuously. The use of polarized X‐rays especially increased enormously the performance of this technology. The reduction of background decreases the limits of detection by up to a factor of 10 in comparison with the traditional technology. Detection limits (in 3σ) of 1ppm are achieved for sulphur and chlorine. Generally the simultaneous multi‐element analysis allows the determination of all elements between Mg and U. Screening analysis with automatic matrix detection enables the quantitative analysis of waste or used oil with unknown water content. The high performance of this technology is proved by several applications.

This paper aims to provide a sensor for fast, sensitive and selective ethylene (C₂H₄) concentration measurements.

The paper developed a sensor platform based on tunable laser absorption spectroscopy with a 3,266-nm interband cascade laser (ICL) as an optical source and a hollow waveguide (HWG) as a gas cell. The ICL wavelength was scanned across a C₂H₄ strong fundamental absorption band, and an interference-free C₂H₄ absorption line located at 3,060.76 cm⁻¹ was selected. Wavelength modulation spectroscopy with the second harmonic detection (WMS-2f) technique was used to improve the sensitivity. Furthermore, the HWG gas cell can achieve a long optical path in a very small volume to improve the time response.

The results show excellent linearity of the measured 2f signal and the C₂H₄ concentration with a correlation coefficient of 0.9997. Also, the response time is as short as about 10 s. The Allan variance analysis indicates that the detection limit can achieve 53 ppb with an integration time of 24 s.

The ethylene sensor has many meaningful applications in environmental monitoring, industrial production, national security and the biomedicine field.

The paper provides a novel sensor architecture which can be a versatile sensor platform for fast and sensitive trace-gas detection in the mid-infrared region.