Low-cost field test kits for arsenic detection in water
01 Jan 2014-Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering (J Environ Sci Health A Tox Hazard Subst Environ Eng)-Vol. 49, Iss: 1, pp 108-115
TL;DR: Though the kits were meant for qualitative assay, the results with unknown concentrations of real samples, when compared with atomic absorption spectrophotometer (AAS) were in good agreement as revealed by the t-test.
Abstract: Arsenic, a common contaminant of groundwater, affects human health adversely. According to the World Health Organization (WHO), the maximum recommended contamination level of arsenic in drinking water is 10 μg/L. The purpose of this research was to develop user-friendly kits for detection of arsenic to measure at least up to 10 μg/L in drinking water, so that a preventive measure could be taken. Two different kits for detection of total arsenic in water are reported here. First, the arsenic in drinking water was converted to arsine gas by a strong reducing agent. The arsine produced was then detected by paper strips via generation of color due to reaction with either mercuric bromide (KIT-1) or silver nitrate (KIT-2). These were previously immobilized on the detector strip. The first one gave a yellow color and the second one grey. Both of these kits could detect arsenic contamination within a range of 10 μg/L-250 μg/L. The detection time for both the kits was only 7 min. The kits exhibited excellent performance compared to other kits available in the market with respect to detection time, ease of operation, cost and could be easily handled by a layman. The field trials with these kits gave very satisfactory results. A study on interference revealed that these kits could be used in the presence of 24 common ions present in the arsenic contaminated water. Though the kits were meant for qualitative assay, the results with unknown concentrations of real samples, when compared with atomic absorption spectrophotometer (AAS) were in good agreement as revealed by the t-test.
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08 Jul 2015
TL;DR: In this article, the authors highlight the need for better portable arsenic contamination detection, and describe how microfluidic technology may be developed to address this need, and comment on their potential for portable microfluidity adaptation.
Abstract: Arsenic contamination of drinking water is a major global problem, with contamination in Bangladesh deemed most serious. Although the current World Health Organisation (WHO) maximum contamination limit (MCL) for arsenic in drinking water is 10 μg L−1, due to practical and economic constraints, the standard limit in Bangladesh and many other developing nations is 50 μg L−1. We propose that an ideal arsenic sensor, designed for routine monitoring, will have five essential qualities: sensitivity and selectivity for arsenic; speed and reliability; portability and robustness; reduced health and environmental risks; and affordability and ease of use for local technicians. It is our opinion that many of these characteristics can be accentuated by microfluidic systems. We describe candidate colorimetric, electrochemical, biological, electrophoretic, surface-sensing, and spectroscopic methods for arsenic detection; and comment on their potential for portable microfluidic adaptation. We also describe existing developments in the literature towards the ultimate creation of microfluidic total analysis systems (μTASs) for arsenic detection. The fundamental purpose of this review is to highlight the need for better portable arsenic contamination detection, and describe how microfluidic technology may be developed to address this need.
99 citations
TL;DR: A paper-based microfluidic device is fabricated that can rapidly detect very low concentrations of As3+ ions using a gold nanosensor, Au-TA-TG as discussed by the authors.
Abstract: A paper based microfluidic device is fabricated that can rapidly detect very low concentrations of As3+ ions using a gold nanosensor, Au–TA–TG. This simple but efficient system develops a visible bluish-black colour precipitate due to the formation of nanoparticle aggregates through transverse diffusive mixing of Au–TA–TG with As3+ ions on a paper substrate. The approach is extremely selective for arsenic with a detection limit of 1.0 ppb, which is lower than the WHO's reference standard for drinking water.
90 citations
TL;DR: RJB-2 owing to its intrinsic abilities of plant growth promotion even in presence of high concentrations of arsenic could inhibit arsenic uptake completely and therefore it could be used in large-scale cultivation for phytostabilization of plants.
84 citations
TL;DR: The iridium(iii) complex 1 was synthesized and employed in constructing an assay which is based on a G-quadruplex for detecting arsenic ions in aqueous solution and showed high selectivity towards arsenic ions over other metal ions.
Abstract: In this work, the iridium(iii) complex 1 was synthesized and employed in constructing an assay which is based on a G-quadruplex for detecting arsenic ions in aqueous solution. The assay achieved a detection limit of 7.6 nM (ca. 0.57 μg L-1) and showed high selectivity towards arsenic ions over other metal ions. Additionally, the assay could function in natural water and a simple microfluidic chip was used to investigate the potential of this platform for real-time detection.
49 citations
TL;DR: This work implements a system that compares the concentration of two signal molecules, and tunes GFP expression proportionally to their relative abundance, performed via molecular titration between an orthogonal σ factor and its cognate anti-σ factor.
Abstract: In many biotechnological applications, it is useful for gene expression to be regulated by multiple signals, as this allows the programming of complex behavior. Here we implement, in Escherichia coli, a system that compares the concentration of two signal molecules, and tunes GFP expression proportionally to their relative abundance. The computation is performed via molecular titration between an orthogonal σ factor and its cognate anti-σ factor. We use mathematical modeling and experiments to show that the computation system is predictable and able to adapt GFP expression dynamically to a wide range of combinations of the two signals, and our model qualitatively captures most of these behaviors. We also demonstrate in silico the practical applicability of the system as a reference-comparator, which compares an intrinsic signal (reflecting the state of the system) with an extrinsic signal (reflecting the desired reference state) in a multicellular feedback control strategy.
48 citations
References
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TL;DR: In this paper, the authors applied cathodic stripping voltammetry at a hanging mercury drop electrode for determination of arsenic in samples of zinc oxide intended for use as a feed additive.
Abstract: Cathodic stripping voltammetry at a hanging mercury drop electrode was applied for determination of arsenic in samples of zinc oxide intended for use as a feed additive. The determinations were carried out in acidic medium in the presence of Cu(II). The As(V) was prereduced to As(III) by potassium iodide and ascorbic acid at ambient temperature. The detection limit was 0.1 ng mL−1. The feasibility of simultaneous determination of arsenic and cadmium in such analysis was also shown. The electrothermal atomic absorption spectrometry was used as a reference method.
15 citations
"Low-cost field test kits for arseni..." refers methods in this paper
...Arsenic in feed additives was also detected by a cathodic stripping voltammetry (CSV) technique using a hanging mercury drop electrode.[11] Anderson et al....
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9 citations
"Low-cost field test kits for arseni..." refers background in this paper
...The presence of arsenic in drinking water is due to either its natural presence in surface and in groundwaters,[2] or as a result of human activities such as industrial applications,[3] leather and wood treatments,[4] use of pesticides.[5] As per WHO’s recommendation, the maximum allowable contamination level of arsenic in drinking water is 10 μg/L....
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