Detection of trace arsenic in drinking water: challenges and opportunities for microfluidics

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.

Biogenic and Synthetic MnO2 Nanoparticles: Size and Growth Probed with Absorption and Raman Spectroscopies and Dynamic Light Scattering

“…This phenomenon is a constraint on evaluating the role of MnO 2 in environmental oxidation and sequestration processes. For example, arsenic in groundwater is a serious health problem of global proportions, 148,149 and there is great interest in the potential of MnO 2 to remediate arsenic in situ, or in drinking water filters. 150−152 Arsenate (As V ) is strongly adsorbed on MnO 2 , as well as Fe oxides surfaces, and arsenite (As III ) can be oxidized by MnO 2 .…”

Review of analytical techniques for arsenic detection and determination in drinking water

“…Another spectroscopic technique, chemiluminescence (CL), detects arsenic in its gaseous state. 11 The relevant literature on the spectroscopic techniques is summarised in the Table 1.…”

“…LIBS analysis of water samples, on the other hand, can be performed using a wood substrate. 11 The main advantage of LIBS is that the entire setup is quite simple, consisting of only a neodymium-doped yttrium aluminum garnet (Nd-YAG) laser, a high sensitivity spectrometer, and a computer for data acquisition. LIBS has been used to detect arsenic in solution at concentrations levels around 83 ppb.…”

“…70,71 Yogarajah et al have summarised and compared all the relevant Gutzeit method based Arsenic Kits in a single table. 11 The relevant literature about the commercial kits based on Gutzeit method are summarised in the Table 4.…”

“…11,12 The most selective and sensitive methods for determination of total arsenic and its species in water are coupled techniques including chromatography, optical methods and mass spectrometry. 2,11,12 Coupled techniques are where combined methods e.g. chromatographic and spectroscopic are used to determine arsenic levels.…”