Detection Of Contaminants In Water Research Articles

Upconversion fluorescence-based paper disc for multiplex point-of-care testing in water quality monitoring

Water quality monitoring is of great significance for human health, which involves a large number of distinct targets detection, such as pathogens, heavy metal ions, and toxins. Traditional detection methods usually carried out in well-equipped central labs are subjected to time, labor, and expense consumption, thus not suitable for implementing water quality monitoring at point of care, where the detection implemented on a multiplexed, miniaturized, and simplified device with rapid and sensitive answer out is desired. To this end, we developed a paper disc relying on upconversion fluorescence signal and aptamer recognition probes for multiplex detection of water contaminants with high sensitivity and specificity. Finally, several different typical kinds of water contaminants have been successfully detected on our paper disc with limit of detection of 115 cfu/mL for Salmonella, 3 ng/mL for Ochratoxin A and Microcystin-LR, 20 nM for Hg2+ and 4 nM for Pb2+, respectively. Additionally, we designed a compact smartphone-based reading device to enable water quality monitoring at point-of-care. Furthermore, this paper disc-based detection platform can be extended to apply to multiplex detection for disease diagnosis and food safety monitoring.

A novel multifunctional Tb-MOF fluorescent probe displaying excellent abilities for highly selective detection of Fe3+, Cr2O72− and acetylacetone

Metal-organic frameworks (MOFs) show the pre-eminence over other traditional fluorescent probes in the detection of water contaminants. Here, a novel lanthanide metal-organic framework Tb-MOF was successfully constructed by anchoring Tb3+ and 4,4'-(4-amino-1,2,4-triazol-3,5-diyl)dibenzoic acid (H2atdbc) which exhibited high chemical stability and water stability. Furthermore, sensing experiments showed that Tb-MOF could be used as a multifunctional probe to detect Fe3+ (LOD ​= ​5.01 ​× ​10-7 ​mol ​L-1, Ksv ​= ​1.28 ​× ​104 ​L ​mol-1), Cr2O72− (LOD ​= ​2.92 ​× ​10-6 ​mol ​L-1, Ksv ​= ​8454.37 ​L ​mol-1) and acetylacetone (LOD ​= ​5.59 ​× ​10-4 ​mol ​L-1, Ksv ​= ​12.32 ​L ​mol-1) separately. PXRD, ICP-MS, IR and UV–vis spectra were conducted to explore the detection mechanisms. The experiments showed that the detection mechanism for Fe3+ was energy transfer and ion exchange, and the detection mechanisms for Cr2O72− and acetylacetone were energy transfer.

Liquid testing with your smartphone

Surface tension is an important property of liquids. It has diverse uses such as testing water contamination, measuring alcohol concentration in drinks, and identifying the presence of protein in urine to detect the onset of kidney failure. Today, measurements of surface tension are done in a lab environment using costly instruments, making it hard to leverage this property in ubiquitous applications. In contrast, we show how to measure surface tension using only a smartphone. We introduce a new algorithm that uses the small waves on the liquid surface as a series of lenses that focus light and generate a characteristic pattern. We then use the phone camera to capture this pattern and measure the surface tension. Our approach is simple, accurate, and available to anyone with a smartphone. Empirical evaluations show that our mobile app can detect water contamination and measure alcohol concentration. Furthermore, it can track protein concentration in the urine, providing an initial at-home test for proteinuria, a dangerous complication that can lead to kidney failure.

FG-LiquID

Contact-less liquid identification via wireless sensing has diverse potential applications in our daily life, such as identifying alcohol content in liquids, distinguishing spoiled and fresh milk, and even detecting water contamination. Recent works have verified the feasibility of utilizing mmWave radar to perform coarse-grained material identification, e.g., discriminating liquid and carpet. However, they do not fully exploit the sensing limits of mmWave in terms of fine-grained material classification. In this paper, we propose FG-LiquID, an accurate and robust system for fine-grained liquid identification. To achieve the desired fine granularity, FG-LiquID first focuses on the small but informative region of the mmWave spectrum, so as to extract the most discriminative features of liquids. Then we design a novel neural network, which uncovers and leverages the hidden signal patterns across multiple antennas on mmWave sensors. In this way, FG-LiquID learns to calibrate signals and finally eliminate the adverse effect of location interference caused by minor displacement/rotation of the liquid container, which ensures robust identification towards daily usage scenarios. Extensive experimental results using a custom-build prototype demonstrate that FG-LiquID can accurately distinguish 30 different liquids with an average accuracy of 97%, under 5 different scenarios. More importantly, it can discriminate quite similar liquids, such as liquors with the difference of only 1% alcohol concentration by volume.

Cobalt oxide-based nanomaterial for electrochemical sensor applications

Amongst the extended list of metal oxides, Co3O4 has gained envisioned attention in various technological fields. It has a proven record of promising material in optical, optoelectronics, sciences, engineering, medicines and biological fields of studies. Co3O4 is a promising candidate due to its large surface-to-volume ratio, simple preparation methods, higher well-defined electrochemical redox activity, high theoretical capacity, low cost, and stable chemical states. Co3O4 has been used in various applications such as fuel cells, photoelectrochemical water splitting, solar cells, supercapacitors, batteries and electrochemical sensors due to its applicability in various fields. It has shown promising outcomes as an electrochemical sensor in various areas such as in the detection of water contamination, as physiological molecule detectors etc. this mini-review summarizes the fields of contaminated water, as fuel and also in the physiological system.

High-Performance Water Harvester Framework for Triphasic and Synchronous Detection of Assorted Organotoxins with Site-Memory-Reliant Security Encryption via pH-Triggered Fluoroswitching.

Atmospheric water harvesting, triphasic detection of water contaminants, and advanced antiforgery measures are among important global agendas, where metal-organic frameworks (MOFs), as an incipient class of multifaceted materials, can affect substantial development of individual properties at the interface of tailor-made fabrication. The chemically robust and microporous MOF, encompassing contrasting pore functionalization, exhibits an S-shaped water adsorption curve at 300 K with a steep pore-filling step near P/P0 = 0.5 and shows reversible uptake-release performance. Density functional theory (DFT) studies provide atomistic-level snapshots of sequential insertion of H2O molecules inside the porous channels and also portray H-bonding interactions with polar functional sites in the two-fold interpenetrated structure. The highly emissive attribute with an electron-pull system benefits the fast-responsive framework and highly regenerable detection of four classes of organic pollutants (2,4,6-trinitrophenol (TNP), dichloran, aniline, and nicotine) in water at a record-low sensitivity. In addition to solid-, liquid-, and vapor-phase sensing, host-guest-mediated reversible fluoroswitching is validated through repetitive paper-strip monitoring and image-based detection of food sample contamination. Structure-property synergism in the electron transfer route of sensing is justified from DFT calculations that describe the reshuffling of molecular orbital energy levels in an electron-rich network by each organotoxin, besides evidencing framework-analyte supramolecular interactions. The MOF further delineates the pH-responsive luminescence defect repair via site-specific emission modulation, wherein reversibly alternated "encrypted and decrypted" states are utilized as highly reusable anticounterfeiting labels over multiple platforms and conceptualized as artificial molecular switches. Aiming at self-calibrated, advanced security claims, a NOR-OR coupled logic gate is devised based on commensurate fluorescence-cum-real-time synchronous detection of organic and inorganic (HCl and NH3) pollutants.

A Review of Nanocomposite-Modified Electrochemical Sensors for Water Quality Monitoring.

Electrochemical sensors play a significant role in detecting chemical ions, molecules, and pathogens in water and other applications. These sensors are sensitive, portable, fast, inexpensive, and suitable for online and in-situ measurements compared to other methods. They can provide the detection for any compound that can undergo certain transformations within a potential window. It enables applications in multiple ion detection, mainly since these sensors are primarily non-specific. In this paper, we provide a survey of electrochemical sensors for the detection of water contaminants, i.e., pesticides, nitrate, nitrite, phosphorus, water hardeners, disinfectant, and other emergent contaminants (phenol, estrogen, gallic acid etc.). We focus on the influence of surface modification of the working electrodes by carbon nanomaterials, metallic nanostructures, imprinted polymers and evaluate the corresponding sensing performance. Especially for pesticides, which are challenging and need special care, we highlight biosensors, such as enzymatic sensors, immunobiosensor, aptasensors, and biomimetic sensors. We discuss the sensors’ overall performance, especially concerning real-sample performance and the capability for actual field application.

Hydrophilic graphene quantum dots as turn-off fluorescent nanoprobes for toxic heavy metal ions detection in aqueous media

Efforts are being made to develop fast, cost-effective and sensitive sensor to detect water contamination by toxic heavy metal ions. The oxygenated functional groups decorated graphene quantum dots (GQDs) effectively enhances the aqueous solubility and considered as a more desirable and simple sensing material with high sensitivity. Here, photoluminescence (PL) property of GQDs has been employed to devise an optical nanosensor for the detection of toxic heavy metal ions in aqueous media. Hydrothermal method was employed to synthesize highly fluorescent and water soluble GQDs. The fluorescence intensity reduces with the increase in toxic heavy metal ions concentration. The observed PL was analyzed by the Stern-Volmer equation to study the fluorescent quenching mechanism of the system. Nonlinear behavior of Stern-Volmer plot suggests that the reduction in the fluorescent intensity is due to the combination of dynamic and static processes. The fluorescence quenching results showed that, the as synthesized GQDs are an efficient fluorescent probe for heavy metal ions viz. Hg2+, Cd2+ and Pb2+ with the detection limit of 1.171 μM, 2.455 μM and 2.011 μM respectively. This study shows the viability of GQDs as promising material for sensing the heavy metal ions in aqueous solution.

Optical nanosensors based on fluorescent carbon dots for the detection of water contaminants: a review

The increasing contamination of environmental media is a serious health issue requiring advanced methods to detect actual and emerging pollutants. In particular, high-sensitivity sensors for monitoring water pollutants are under deep investigation. Here, we review the synthesis, optical properties and applications of carbon dots for sensing contaminants in water samples. Fluorescence-based sensors have achieved ultrasensitive detection at nanomolar to picomolar concentrations. Carbon dot sensors have unique advantages such as biocompatibility, easy preparation, optical activity and wide applicability.

Digital colorimetric analysis for estimation of iron in water with smartphone-assisted microfluidic paper-based analytical devices

ABSTRACT Microfluidic paper-based analytical devices are emerging as promising options for on-the-spot detection of chemical contaminants in water. The coupling of these devices with digital imaging technology has attracted immense interest in developing portable sensor applications. However, the potential of digital techniques still remains to be fully explored. In this work, we integrate digital imaging with microfluidic paper-based analytical devices to develop a portable colorimetric assay for iron. The experimental conditions are optimised using image analysis and the effects of imaging equipment and colorimetric analysis methods on the readout of devices are studied using numerical, graphical and statistical techniques. The experimental results are obtained for the estimation of iron contamination in water samples using a colorimetric assay based on iron (III)-thiocyanate reaction. The digital image acquisition approach using smartphone as imaging equipment is adopted for on-the-spot colorimetric data collection. Image processing techniques are employed to estimate the iron concentration in water from digital images. Greyscale colour intensity obtained from a digital image is identified as a readout of the analytical device and employed for quantitative assessment. The limit of detection for iron is estimated to be 0.26 ppm. The microfluidic approach offers good recovery and repeatability with relative standard deviation of 1.4%. The maximum percentage difference for intensities between the image analysis methods is 4.94% and that between the imaging equipment is 9.96%. The gradients of regression lines for pairwise equipment and method outputs with zero intercept range from 0.9931 to 1.0162 with high values of coefficients of determination. The correlation coefficient values for various paired comparisons (>0.99) suggest strong agreement. Statistical test results suggest no significant differences between methods and between imaging equipment (significance level 0.05). The findings suggest the efficacy of digital imaging and colorimetric analysis for paper-based analytical devices.

Ecological monitoring in the impact zone of an industrial enterprise producing alumina

Ecological monitoring in the impact zone of an industrial enterprise that produces alumina will ensure effective management of production processes. In the course of monitoring in the area of sludge farm near Achinsk alumina plant in Russia, systematic observations and timely detection of underground water contamination, determining the size of the contamination area, as well as studying the development of the underground water contamination area in time and space is carried out. In wells located in the immediate proximity of the sludge storage, maximum values of alkalinity, potassium and bicarbonate are observed and away from the sludge storage, the values of these indicators decrease. It is established that the zone of negative impact is located within 300-500 m from the contour of the sludge storage, outside of which the chemical composition of underground water almost corresponds to the background. Monitoring studies of the soil in the area adjacent to the sludge storage showed their recovery after reclamation and phytosanation. The analysis has shown that the ecological monitoring system at JSC “RUSAL Achinsk” combines all the necessary components: instrument and hardware maintenance, a measurement organization system, and a set of methods for analyzing the results of observations, providing all the necessary conditions for its implementation in practice.

Novel nanoscale Yb-MOF used as highly efficient electrode for simultaneous detection of heavy metal ions

It is essential to develop new nanomaterials able to improve sensing performance of electrochemical sensors for determination of heavy metal pollutants. In this work, a novel nanoscale metal–organic-framework material (Yb-MOF) with Ytterbium (Yb) rare-earth metal core and benzenetricarboxylic (BTC) ligands was prepared in aqueous conditions using hydrothermal approach. The results have revealed highly porous structure of the as-synthesized material with specific active area up to 1166 m2 g−1. A sensing platform was then constructed by drop-casting Yb-MOF onto glassy carbon electrode for detection of two most commonly found heavy metal ion pollutants (Cd2+ and Pb2+) in water sources. The nanoporous structure of Yb-MOF is very profitable to the selective preconcentration of targeted metal ions. The detection limits were estimated to be 3.0 ppb, 1.6 ppb for Cd2+ and Pb2+ species, respectively. This work provides a new electrochemical sensing platform for fast and sensitive in-situ detection of water contaminants.

Water Sampling Module for Collecting and Concentrating Legionella pneumophila from Low-to-Medium Contaminated Environment.

The detection of water contamination with Legionella pneumophila is of critical importance to manufacturers of water processing equipment and public health entities dealing with water networks and distribution systems. Detection methods based on polymerase chain reaction or biosensor technologies require preconcentration steps to achieve attractive sensitivity levels. Preconcentration must also be included in protocols of automated collection of water samples by systems designed for quasi-continuous monitoring of remotely located water reservoirs for the presence of L. pneumophila. We designed and characterized a water sampling module for filtration and backwashing intended for analysis of low-to-medium contaminated water, typically with L. pneumophila bacteria not exceeding 50 colony-forming units per milliliter. The concentration factors of 10× and 21× were achieved with 0.22 and 0.45 µm filters, respectively, for samples of bacteria prepared in clean saline solutions. However, a 5× concentration factor was achieved with 0.45 µm filters for a heavily contaminated or turbid water typical of some industrial water samples.

A Whole-Cell Biosensor for Point-of-Care Detection of Waterborne Bacterial Pathogens.

Water contamination by pathogenic bacteria is a major public health concern globally. Monitoring bacterial contamination in water is critically important to protect human health, but this remains a critical challenge. Engineered whole-cell biosensors created through synthetic biology hold great promise for rapid and cost-effective detection of waterborne pathogens. In this study, we created a novel whole-cell biosensor to detect water contamination by Pseudomonas aeruginosa and Burkholderia pseudomallei, which are two critical bacterial pathogens and are recognized as common causative agents for waterborne diseases. The biosensor detects the target bacterial pathogens by responding to the relevant quorum sensing signal molecules. Particularly, this study constructed and characterized the biosensor on the basis of the QscR quorum sensing signal system for the first time. We first designed and constructed a QscR on the basis of the sensing module in the E.coli host cell and integrated the QscR sensing module with a reporting module that expressed an enhanced green fluorescent protein (EGFP). The results demonstrated that the biosensor had high sensitivity in response to the quorum sensing signals of the target bacterial pathogens. We further engineered a biosensor that expressed a red pigment lycopene in the reporting module to produce a visible signal readout for the pathogen detection. Additionally, we investigated the feasibility of a paper-based assay by immobilizing the lycopene-based whole-cell biosensor on paper with the aim to build a prototype for developing portable detection devices. The biosensor would provide a simple and inexpensive alternative for timely and point-of-care detection of water contamination and protect human health.

Zinc Oxide Nanoparticles as Antifouling Materials for the Electrochemical Detection of Methylparaben

AbstractThe use of personal care products (PCPs) containing methylparaben (MePa) has been linked with coral reef damage, breast cancer, and endocrine disruption. To monitor such pollutants, the development of simple, fast, and sensitive detection methods is needed. This study reports the electrochemical detection of MePa using a zinc oxide (ZnO) nanoparticle modified glassy carbon electrode. We addressed two main challenges posed by the use of sensing electrodes, that is, the instant fouling of electrodes for the detection of phenolic compounds and the use of expensive or highly complex, multicomponent materials for the detection of water contaminants. By controlling the pH of the reaction solution, ZnO nanoparticles with three different morphologies were synthesized: nanowires, nanocuboids, and nanospheres. The impact of these morphologies on the performance and sensitivity of the fabricated modified electrode was investigated. Under optimum conditions, ZnO nanowires demonstrated the best response compared to the other geometries, with a linear calibration response in the range of 0.02–0.12 mM, and the lowest limit of detection (LOD) of 7.25 μM. The proposed sensor not only offers simplicity and the use of low‐cost materials, but also successfully overcomes the electrode passivation associated with phenol‐containing chemicals and can, therefore, be an attractive candidate for further antifouling applications.

A hydrostable Zn2+ coordination polymer for multifunctional detection of inorganic and organic contaminants in water.

From the perspective of human health and environmental safety, the development of hydrostable fluorescent sensors for the detection of heavy metal ions and nitroaromatics is an important but a challenging issue. To this end, a water-stable Zn2+ coordination polymer formulated as {[Zn(H2L)]·2DMF·3H2O}n (ZnCP) was prepared elaborately by a solvothermal method using a multidentate ligand (H4L) with 2,6-pyridine-dicarboxylic acid spaced by para-substituted benzene. Single-crystal analysis shows that the new ZnCP exhibits one-dimensional chain structural features, which further promoted to afford a wrinkled two-dimensional network structure via inter-chain hydrogen bonding. Powder X-ray diffraction and fluorescence measurements show that it can maintain crystallinity and structural integrity under harsh acidic and alkaline conditions with the pH ranging from 4 to 11. Notably, the bright blue-emissive ZnCP showed selective fluorescence quenching effects for Fe3+ and picric acid (PA), which makes it an excellent chemical sensor for Fe3+ and picric acid (PA) with low detection limits of 0.41 and 0.26 μM in water. The recognition mechanism of Fe3+ could be attributed to UV absorption competition and resonance energy transfer in the aid of weak electrostatic interactions, while the recognition mechanism of PA is considered to be a multi-quenching mechanism dominated by absorption competition and PET effects with the assistance of hydrogen bonding. In addition, poly(methyl methacrylate) (PMMA) films doped with ZnCP (ZnCP@PMMA) were developed to provide better sensing performance and portability for practical applications.

Real-time detection of copper contaminants in environmental water using porous silicon Fabry–Pérot interferometers

Water sources are vulnerable to intentional and inadvertent human pollution with thousands of synthetic and geogenic trace contaminants, posing long-term effects on the aquatic ecosystem and human health. Thus, early and rapid detection of water pollutants followed by corrective and preventive actions can lead to the reduction of the overall polluting impact to safeguard public health. This study presents a generic sensing assay for the label-free detection of copper contaminants in environmental water samples using multilayered polyethylenimine (PEI) functionalized porous silicon Fabry-Pérot interferometers. The selective chelating activity of PEI thin-films was monitored in real-time by reflective interferometric Fourier transform spectroscopy (RIFTS) while assessing the improved optical responses. The optimized scaffold of two sequential PEI layers depicted a linear working range between 0.2 and 2 ppm while presenting a detection limit of 0.053 ppm (53 ppb). The specificity of the developed platform was cross-validated against various metallic pollutants and cations commonly found in water bodies (i.e., Cd2+, Pb2+, Cr3+, Fe3+, Mg2+, Ca2+, Zn2+, K+ and Al3+). Finally, as a proof of concept, the analytical performance of the porous interferometers for real-life scenarios was demonstrated in three water samples (tap, ground and irrigation), presenting sufficient adaptability to complex matrix analysis with recovery values of 85-106%. Overall, the developed sensing concept offers an efficient, rapid and label-free methodology that can be potentially adopted for routine on-site detection using a simple and portable device.

Silica-based nanoenzymes for rapid and ultrasensitive detection of mercury ions

Mercury ions are highly toxic and can cause severe damage to humans through food and water contamination, therefore, rapid and sensitive detection of Hg2+ is of vital importance. We synthesized silica-based nanoenzymes by loading Pt nanoparticles on the surface of silica nanoparticles, and the as-synthesized nanoenzyme exhibited an excellent peroxidase-like activity. It was found that silica-based nanoenzymes can specifically reduce Hg2+ to inhibit the catalytic ability of nanoenzymes. By monitoring the color change of 3,3′,5,5′-tetramethylbenzidine, the concentrations of Hg2+ were detected within 20 min. The detection limit was as low as 60 fM with a linear range between 5 pM and 5000 nM. The proposed visual method has the advantages of simple operation, low cost and fast response, and its practicability in complex lake water has also been demonstrated, suggesting its potential as a simple and powerful strategy to evaluate Hg2+ in environmental samples.

A colorimetric/luminescence sensor for detecting MeCN in water: Towards direct detection of dissolved organic contaminants

To address the need for a field-deployable in-situ technique for the accurate and reliable detection of organic contaminants in water, this work reports a new chemical sensing approach for the detection of aqueous MeCN. The approach relies on the reversible colorimetric/luminescent change in a transition metal complex. In this approach, a square planar platinum salt [Pt(tpy)Cl](PF6) (tpy = 2,2′:6′,2″-terpyridine) demonstrated a reversible color change from yellow to red as well as a red shift in emission intensity upon exposure to aqueous MeCN. This observed spectroscopic change was induced by the incorporation of MeCN molecules withing the crystal lattice of the platinum salt, that resulted in an enhancement in the intermolecular Pt•••Pt interactions, which correlatively altered the electronic structure. The spectroscopic response was highly selective and quantitative for aqueous MeCN. This work illustrates a new technique for the rapid, selective, sensitive detection of aqueous MeCN, while also providing a general strategy for the detection of other small molecule contaminants.

Nano-biomaterials in-focus as sensing/detection cues for environmental pollutants

Direct detection of pollutants, such as heavy metals, pesticides, and toxins from waste streams and monitoring of water and soil conditions, are significant challenges in the field of environmental and analytical chemistry. The current techniques implemented for real-time analysis and monitoring of contaminated specimens have been limited due to the lack of tools with broad detection limits and the necessity of expensive laboratory equipment. In this regard, efforts in developing sensing technologies have been put forward during the last years by various research groups. Moreover, cost-effective, compact, and eco-friendly sensors are required. Nanotechnology provides leading biosensors using novel nanofabrication and green synthesis techniques. Nano biosensors utilized for the detection of pollutants exhibit ultra-sensitivity and quick detection time in real-time analysis. Additionally, detection limits at the nanomolar to picomolar level for pollutants have already been reported in the literature. Herein, we summarize nanotechnological advances in green chemical sensors for environmental proposes, focusing on the detection of contaminants in soil and water.