River Water Samples Research Articles

Facile synthesis and fabrication of Mg2SnO4/carbon black as a sustainable electrode for determination of non-steroidal anti-inflammatory drug-flutamide

The accumulation of hazardous pharmaceutical wastes in aquatic organisms, particularly nonsteroidal anti-inflammatory drug molecules, has severe toxicological consequences for both aquatic life and humans. To protect the environment, it is essential to develop a highly efficient device with dual-purpose capabilities for drug detection while minimizing catalyst expenditure. In this work, we explored a simple and effective design for fabricating a magnesium stannate combined with carbon black (Mg2SnO4/CB) nanocomposite as a cost-effective, sustainable electrode material for the electrochemical detection of flutamide (Flu). The Mg2SnO4/CB nanocomposite was synthesized through a simple hydrothermal process followed by sonication. Various analytical methods were used to determine its physico-chemical characteristics. The electrochemical efficiency of Mg2SnO4/CB/GCE was evaluated by detecting Flu, showing a remarkable linear range from 0.6 to 198.4 µM with a sensitivity of 3.91 μA μM−1 cm−2. In addition, the constructed sensor demonstrated excellent selectivity, high repeatability, outstanding reproducibility, and long-lasting stability. The anti-interference experiments yielded a definite current response without any change in peak shifts. Consequently, Mg2SnO4/CB/GCE demonstrated superior performance in determining Flu in human urine and river water samples.

Simple solution and paper-based fluorescent aptasensors for toxic metal ions, thallium(l) and lead(ll).

Heavy metal ions, such as thallium(I) and lead(II) are environmental toxicants known to cause a severe threat to human and ecosystem health. This work investigates aptamers and intercalating chromophore-based complexes for the detection of these toxic species. In one method, a selective label-free "turn-on" biosensor was developed using a G-quadruplex-intercalating agent, berberine. Fluorescence, melting temperature (Tm), and circular dichroism analysis confirmed the affinity and selectivity results, illustrating the potential of these aptasensor methods for improving detection limits. These fluorescence assays were found to perform with a detection limit of 3.4 μM for Tl(I) and 0.84 nM for Pb(II). Furthermore, the assays were challenged successfully with Tl(I) and Pb(II) spiked into river water samples. We next developed paper-based fluorescent assays for Tl(I) and Pb(II), where the aptamer/berberine complex was spotted onto the paper test zone. When Tl(I) or Pb(II) ions solutions were spotted onto the top of the test zone and the spot was illuminated with a portable UV light (365 nm), a strong green fluorescence could be easily visualized with the naked eye. The lowest detection limits achieved with these fluorescent paper-based assays for Tl(I) and Pb(II) were 1.1 nM and 1.6 nM, respectively. The two fluorescent approaches presented here have the potential to be the basis of rapid, fast, and cost-efficient screening assays for these toxic species.

Electrospun Nanofiber Dopped with TiO2 and Carbon Quantum Dots for the Photocatalytic Degradation of Antibiotics

Novel photocatalysts were synthesized through the association of carbon quantum dots (CQDs) with commercial (P25) titanium dioxide (TiO2) by sonication. The resulting TiO2/CQDs composite was then incorporated into the polyamide 66 (PA66) biopolymer nanofibers using the electrospinning technique, considering a composite nanoparticles-to-polymer ratio of 1:2 in the electrospinning precursor solution. The produced nanofibers presented suitable morphology and were tested for the photocatalytic degradation under simulated solar radiation of 10 mg L−1 of amoxicillin (AMX) and sulfadiazine (SDZ), in phosphate buffer solution (pH 8.06) and river water, using 1.5 g L−1 of photocatalyst. The presence of the photocatalyst increased the removal of AMX in phosphate buffer solution by 30 times, reducing the AMX degradation half-life time from 62 ± 1 h (without catalyst) to 1.98 ± 0.06 h. Moreover, SDZ degradation half-life time in phosphate buffer solution was reduced from 5.4 ± 0.1 h (without catalyst) to 1.87 ± 0.05 h in the presence of the photocatalyst. Furthermore, the PA66/TiO2/CQDs were also efficient in river water samples and maintained their performance in at least three cycles of SDZ photodegradation in river water. The presented results evidence that the produced photocatalyst can be a promising and sustainable solution for antibiotics’ efficient removal from water.

Distributions of Fecal Indicators at Aquaculture Areas in a Bay of Republic of Korea.

Aquaculture products, such as clams, scallops, and oysters, are major vectors of fecal-derived pathogens. Male-specific and somatic coliphages are strongly correlated with human noroviruses, the major enteric viruses worldwide. Geographic information system with local land-use patterns can also provide valuable information for tracking sources of fecal-derived pathogens. We examined distributions of four fecal indicator microorganisms, i.e., male-specific and somatic coliphage, total coliform, and Escherichia coli (E. coli) in three river and seawater sampling sites located on the coast of Gomso Bay in the Republic of Korea during the sampling period (from March 2015 to January 2016). Geospatial analyses of fecal indicators and correlation between environmental parameters and fecal indicators or among fecal indicators were also performed. Overall, river water samples showed highest concentrations of both types of coliphage in summer (July 2015). High concentrations of both total coliform and E. coli were detected in river water during the period from July to September 2015. High concentrations of all fecal indicators were found at site GL02, located in the innermost part of Gomso Bay, which has high-density agriculture and residential areas. Environmental factors related to precipitation-cumulative precipitation on and from 3 days before the sampling day (Prep-0 and Prep-3, respectively)-and salinity were strongly correlated with concentrations of all fecal indicators. The present results suggest that investigations of multiple fecal indicators with a systemic geospatial information are necessary for precisely tracking fecal contaminations of aquaculture products.

Application of Fabric Phase Sorptive Extraction as a Green Method for the Analysis of 10 Anti-Diabetic Drugs in Environmental Water Samples

Due to the increased prevalence of diabetes, the consumption of anti-diabetic drugs for its treatment has likewise increased. Metformin is an anti-diabetic drug that is commonly prescribed for patients with type 2 diabetes and has been frequently detected in surface water and wastewaters, thus representing an emerging contaminant. Metformin can be prescribed in combination with other classes of anti-diabetic drugs; however, these drugs are not sufficiently investigated in environmental samples. Fabric phase sorptive extraction (FPSE) has emerged as a simple and green method for the extraction of analytes in environmental samples. In this study, FPSE coupled with a high-performance liquid chromatography diode array detector (HPLC-DAD) was employed for the simultaneous analysis of different classes of anti-diabetic drugs (metformin, dapagliflozin, liraglutide, pioglitazone, gliclazide, glimepiride, glargine, repaglinide, sitagliptin, and vildagliptin) in environmental water samples. Four different fabric membranes were synthesized but the microfiber glass filter coated with sol-gel polyethylene glycol (PEG 300) was observed to be the best FPSE membrane. The parameters affecting the FPSE process were optimized using a combination of one-factor-at-a-time processes and the design of experiments. The FPSE was evaluated as a green extraction method, based on green sample preparation criteria. The FPSE-HPLC-DAD method achieved acceptable validation results and was applied for the simultaneous analysis of anti-diabetic drugs in surface and wastewater samples. Glimepiride was detected below the quantification limit in both lake and river water samples. Dapagliflozin, liraglutide, and glimepiride were detected at 69.0 ± 1.0 μg·L−1, 71.9 ± 0.4 μg·L−1, and 93.9 ± 1.3 μg·L−1, respectively, in the city wastewater influent. Dapagliflozin and glimepiride were still detected below the quantification limit in city wastewater effluent. For the hospital wastewater influent, metformin and glimepiride were detected at 1158 ± 21 μg·L−1 and 28 ± 0.8 μg·L−1, respectively, while only metformin (392.6 ± 7.7 μg·L−1) was detected in hospital wastewater effluent.

Enhanced Pb(II) extraction using a novel chitosan/pectin/carbon composite adsorbent for solid-phase extraction

ABSTRACT This research aimed to present the development of chitosan/pectin/carbon (CPC) materials as adsorbents in the solid-phase extraction (SPE) of Pb(II) from river water samples. The CPC adsorbent shows active groups effectively binding Pb(II) ions. The characterisation included using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDX) to analyse functional groups and evaluate surface morphology with elemental composition. SPE parameters were systematically optimised to enhance adsorption-desorption efficiency, including pH 4.0, Pb(II) concentration of 5 mg L−1, flow rate of 13.3 mL min−1, elution flow rate of 12.8 mL/min using nitric acid (HNO3), a sample volume of 25 mL, eluent volume of 1 mL and concentration at 1.0 M. The results showed that the implementation of the refined CPC-based SPE method for Pb(II) analysis in water samples obtained a recovery range of 101% to 103%, accompanied by a significant 25-fold concentration enrichment of Pb(II). Moreover, the adsorption concentration increased from undetectable levels to 1.27–2.48 mg L−1, reporting the efficacy of the CPC-based SPE method for sensitive and accurate Pb(II) analysis in environmental samples.

Portable paper-based multicolor sensor for sensitive on-site detection of organophosphorus pesticides using a high-efficiency Au+-induced gold nanobipyramids aspect ratio regulation strategy

On-site visual detection of organophosphorus pesticides (OPs) is crucial for safeguarding environmental and food safety. This study presents a robust, sensitive, and portable paper-based multicolor sensor (PMS) for the on-site detection of OPs. The PMS involves a novel Au+-induced gold nanobipyramids (AuNBPs) morphology transformation reaction within a paper-based analytical device (PAD) coupled with a bienzymatic hydrolysis system. The Au+-induced reaction sensitively regulates the aspect ratio of AuNBPs through Au+ disproportionation, which decreases the length of AuNBPs and simultaneously increases the width, accompanied by distinct multicolor changes. Upon performing in the PAD incorporating easily-prepared AuNBPs-deposited nylon membranes, a metal heater, and an oscillator, the Au+-induced reaction exhibits excellent reaction sensitivity, efficiency, reproducibility, AuNBPs stability, and color uniformity. In the bienzymatic hydrolysis system, acetylcholinesterase (AChE) and choline oxidase hydrolyze acetylcholine to product H2O2, which consumes tris(2-carboxyethyl)phosphine hydrochloride (TCEP), maintaining free Au+ for the disproportionation in the Au+-induced system, while the presence of OPs inhibits AChE activity, preserving TCEP to chelate Au+ and hindering the disproportionation. Under optimized conditions, the PMS exhibited eight dichlorvos concentration-corresponding color changes with a visual detection limit of 30 μg/L and a spectrometry detection limit of 8.1 μg/L. It achieved recoveries of 85.4–101.9 % in river water, drinking water, rice, and Chinese cabbage samples with relative standard deviations (n = 5) < 6 %. Thus, this study offers a portable, sensitive, reliable, and practical on-site detection method for OPs. Additionally, the proposed Au+-induced AuNBPs morphology transformation system within the PAD offers promising alternative strategies for developing other AuNBPs-based colorimetric sensors.

Prevalence of antibiotic resistance genes in bacteria from Gomti and Ganga rivers: implications for water quality and public health.

Rivers serve as a significant habitat and water sources for diverse organisms, including humans. An important environmental and public health concern is the increase in antibiotic-resistant bacteria (ARBs) and genes (ARGs) in aquatic ecosystems brought about by excessive pollutant flow. The research highlighted that river water, which is receiving discharge from wastewater treatment plants, is harbouring multidrug-resistant bacteria. River water samples were collected in January, April, July and October 2022 from three separate locations of each Gomti and Ganga river. A total of 114 bacteria were isolated from Gomti as well as the Ganga River. All the isolates were tested for their resistance to various antibiotics by disc diffusion method. The isolated bacteria were tested for the antibiotic resistance genes using PCR and were identified by 16s rRNA sequencing. The ARBs percentages for each antibiotic were as follows: ampicillin (100%); cefotaxime (96.4, 63.1%); erythromycin (52.6, 57.8%); amikacin (68.4, 50.8%); tetracycline (47.3, 54.3%); nalidixic acid (47.3, 45.6%); streptomycin (68.4, 49.1%); gentamycin (43.8, 35%); chloramphenicol (26.3, 33.3%); neomycin (49.1, 29.8%) and ciprofloxacin (24.5, 7.01%). Further, antibiotic resistance genes in Gomti and Ganga water samples disclose distinctive patterns, including resistance to ermB (25, 40%); tetM (25, 33.3%); ampC (44.4, 40%) and cmlA1 (16.6%). Notably cmlA1 resistant genes were absent in all bacterial strains of the Gomti River. Additionally, gyrA gene was not found in both the river water samples. The presence of ARGs in the bacteria from river water shows threat of transferring these genes to native environmental bacteria. To protect the environment and public health, constant research is necessary to fully understand the extent and consequences of antibiotic resistance in these aquatic habitats.

Heavy Metal Identification in Water Resources and the Surrounding Environment of the Cirasea Riparian Zone, Indonesia

The Cirasea River can provide water for both the Bandung basin and agricultural irrigation. Intensive agriculture, industry, and land use changes could have an impact on water quality. The purpose of this study is to look at the origins of heavy metals in riparian water resources. Heavy metal analysis was performed on 13 groundwater and river water samples. Heavy metals in water sources were compared with sediment and soil. The samples were analyzed for heavy metals using an AAS instrument. The research method employs statistical, geographical, and heavy metal pollution index (HPI). The HPI for river water was 131, whereas groundwater was 93. River water with an HPI value of more than 100 is highly polluted, indicating that it is unsafe for human consumption and has negative health consequences. Data verification with heavy metals in sediments reveals the presence of heavy metals coming from geogenic circumstances in various locations in the upstream area. Heavy metals in downstream areas result from geological factors and anthropogenic activities in the surrounding area. The long-term effects of heavy metal pollution along the riparian zone will become apparent. More research is needed on communities that depend on groundwater supplies along the Cirasea watershed.

Preparation of a New Hexafluorobutanol-Farnesol Based Supramolecular Solvent and Its Application in Microextraction of Sudan Dyes From Beverage and Water Samples.

In this work, a new supramolecular solvent (SUPRAS) was prepared for the first time using hexafluorobutanol (HFB) and farnesol (FO). FO acts as an amphiphile and HFB as a coacervation inducer and density regulator. The method of dispersive liquid-liquid microextraction followed by high-performance liquid chromatography, supported by a vortex technique, was established using the prepared SUPRAS for the determination of Sudan dyes in aqueous samples. The extraction parameters, including FO content, HFB content, vortex time, salt addition, and solution pH, were thoroughly investigated and optimized. Under the optimized conditions, the linearity range is 10-750ng/mL for Sudan I, and 10-1000ng/mL for Sudan III and Sudan IV, respectively. The limits of detection for Sudan dyes were in the range of 0.8-3.1ng/mL. The inter- and intra-day relative standard deviations for Sudan dyes were in the range of 1.3%-4.1% and 0.2%-2.6%, respectively. Finally, the proposed method was applied to the determination of Sudan dyes in beverage and river water samples with recoveries ranging from 93.9% to 122.1%. Compared to conventional techniques for the extraction of Sudan dyes in real samples, the proposed method is simpler, faster, and more environmentally friendly.

Evaluating Groundwater Quality for Drinking and Irrigation Purposes and Health Risk Assessment in West Midnapore District of West Bengal, India

Groundwater quality in the West Midnapore district of West Bengal, India is affected by anthropogenic activities as well as by water quality of Subarnarekha and Kangsabati rivers. This study aims to assess quality of groundwater and river water for drinking and irrigation usage, and assess the health risks of the people consuming the water across the rivers. The study also explores the groundwater-river water interaction. The river water and groundwater samples were collected three times during monsoon season from 14 sites across the rivers. The samples were analyzed for 11 water quality parameters, i.e., pH, total dissolved solids (TDS), total hardness (TH), major anions and cations, and iron (Fe). The groundwater was found slightly acidic (mean pH ~ 6.71) and correlated with nitrate concentrations. Most of the water quality parameters were found within their permissible limits of drinking water. However, elevated concentrations of potassium (K), ammonium (NH4), magnesium (Mg), phosphate (PO4), sodium (Na), and Fe were detected at some places, which were likely due to use of fertilizers. Water quality index (WQI), sodium absorption ratio (SAR), and percentage Na values were computed to evaluate the groundwater quality. The mean WQI value of 37.07 showed that the majority of groundwater samples met drinking water standards. Groundwater was also found suitable for irrigation (SAR ~ 0.26 to 1.62 meq L-1 and percentage Na ~ 13.10% to 78.12%). Health risk assessments suggested minimal immediate risks, though high Na levels in certain areas raised concerns. Piper plot showed that increased calcium concentrations in groundwater were mainly due to interactions between river water and groundwater. Overall, groundwater quality did not present any harmful health hazards to the community. The findings of this study can be instrumental for groundwater managers in identifying potential areas for treating groundwater quality.

Selective and visual detection of UO22+ and Al3+ in real water by a luminescent Tb(Ⅲ) metal-organic framework sensor

The development of sensors for monitoring UO22+ and Al3+ has drawn widespread attention due to their threat to human health and environment. However, highly selective and visual detection of UO22+ and Al3+ in complex real water environment is still a challenge. Herein, a luminescent terbium organic framework Tb-MOF [Tb2(TP)3·(H2O)4] was successfully synthesized for selectively detecting UO22+ and Al3+ based on luminescence quenching, with detection limits of 80.0 μg/L and 76.5 μg/L, respectively. The luminescence sensing mechanisms for UO22+ and Al3+ ions were elucidated. Further studies indicated that this sensor can detect UO22+ and Al3+ with satisfactory recoveries in real water samples such as river water and tap water. Moreover, a low-cost and portable luminescent test strip based on Tb-MOF were prepared, which can be used to visually recognize UO22+ and Al3+in real river water samples. As the first Tb-MOF luminescent sensor for the detection of both UO22+ and Al3+ ions, it has good application prospects for real-time and on-site discriminating the two ions by naked eyes in actual environments.

Effect Of Adsorptive Treatment on the Physico-Chemical Parameters of Cauvery River Water Samples

Effect Of Adsorptive Treatment on the Physico-Chemical Parameters of Cauvery River Water Samples

Preparation and evaluation of polymeric ionic liquid functionalized microparticles as the efficient adsorbent for pipette tip solid phase extraction of sulfonamides

Sulfonamides (SAs) residues are commonly found in environmental samples, which is highly concerning for public safety and environmental protection. The detection of SAs is quite important but challenging. In this work, a kind of polymeric ionic liquid functionalized microparticles (PIL-FM) was synthesized via a simple free radical polymerization reaction, and applied as the adsorbent for pipette tip solid phase extraction (PT-SPE) of three SAs from river water, milk powder and honey samples. The adsorption performance of PIL-FM on SAs were evaluated using adsorption kinetics and adsorption isotherms, and the results showed that PIL-FM had the best selectivity for SMZ with the maximum adsorption capacity was as high as 45.05 mg·g−1. The extraction process was optimized and the adsorption mechanism was preliminarily discussed. PIL-FM has the excellent selectivity for SAs mainly because of the strong π-π interaction, and the electrostatic repulsion between them in the elution step also has a positive impact. Under optimal conditions, combined with HPLC, this PT-SPE method had wide linearity (0.2–100 μg·L−1, R2 ≥ 0.9998) and low limits of detection (0.06–0.08 μg·L−1). The intra-day and inter-day repeatability were found to be 3.7 %–4.6 % and 4.5 %–6.2 %, respectively. The suggested PT-SPE method is simple, low cost, rapid, and efficient to extract SAs, and can be applied for the monitoring of SAs residues in the aquatic environment and in food.

Decontamination Potential of Ultraviolet Type C Radiation in Water Treatment Systems: Targeting Microbial Inactivation

Access to safe water and sanitation is a critical global challenge, posing significant health risks worldwide due to waterborne diseases. This study investigates the efficacy of ultraviolet type C radiation as a disinfection method for improving water quality. The research elucidates UV-C’s mechanism of action, highlighting its ability to disrupt DNA and RNA replication, thereby inactivating pathogens. Furthermore, the study analyses the influence of key factors on UV-C disinfection effectiveness, including water turbidity and the presence of dissolved organic matter, which can attenuate UV-C penetration and reduce treatment efficiency. The experimental results demonstrate a substantial reduction in microbial content following UV-C treatment. River water samples exhibited a 57.143% reduction in microbial load, while well water samples showed a 50% reduction. Notably, Escherichia coli (E. coli) concentrations decreased significantly, with an 83.33% reduction in well water and a 62.5% reduction in borehole water. This study makes a novel contribution to the understanding of UV-C disinfection by identifying the presence of resistant organisms, including Adenoviruses, Bacterial spores, and the Protozoan Acanthamoeba, in water samples. This finding expands the scope of UV-C research beyond easily culturable bacteria. To address this challenge, future investigations should explore synergistic disinfection strategies, such as combining UV-C treatment with advanced oxidation processes. Optimising UV-C system designs and developing robust, real-time monitoring systems capable of detecting and quantifying known and emerging UV-resistant pathogens are crucial for ensuring comprehensive water decontamination.

A green procedure for the determination of bioavailable forms of aluminum in natural waters by electrothermal atomic absorption spectroscopy combined with microextraction technique.

Aluminum is a prevalent element in nature, but bioavailable forms of aluminum are toxic to plants, animals, and humans. The present study is dedicated to the development of an ecologically friendly, fast, simple, reliable, sensitive, and accurate improved procedure for the determination of subtrace concentrations of bioavailable forms of aluminum in natural waters. The procedure includes the separation and pre-concentration of bioavailable forms of aluminum using vortex-assisted liquid-liquid microextraction (VALLME) of ionic associates with salicylaldehyde 4-picolinhydrazone (SAPH) and sodium dodecyl sulfate (DDSNa) by isoamylacetate (200μl) and direct electrothermal atomic absorption spectroscopy (ETAAS). The SAPH reagent interacts only with water-soluble forms of aluminum. SAPH is used for the pre-concentration of bioavailable forms of aluminum as well as a chemical modifier; it increases the absorbance and the precision of the analytical signal of aluminum. The calibration curve shows the linear dependence in the range of 0.05-86μg⋅L-1 of the aluminum concentration (R2 = 0.992), with the limit of detection at 0.015μg⋅L-1 and the limit of quantification at 0.05μg⋅L-1. The accuracy of the proposed procedure for bioavailable forms of aluminum determination was verified on model solutions and against a reference method on natural samples of river and lake waters (RSD 3.2-5.2%, recovery 97.1-103.4%).

Detection and Measurement of Bacterial Contaminants in Stored River Water Consumed in Ekpoma

This study was conducted in Ekpoma, a town dependent on rainwater and river water from nearby areas because of a lack of groundwater sources, and the physicochemical and bacteriological (heterotrophic plate count [HPC], total coliform count [TCC], and fecal coliform count [FCC]) properties of 123 stored river water samples grouped into five collection districts (EK1 to EK5). The results were compared with regulatory standards and previous regional studies to identify water quality trends. While most physicochemical properties met drinking water standards, 74% of samples had pH values &gt; 8.5. Twenty-seven samples were fit for drinking, with EK4 having the highest number of bacterio-logically unsuitable samples. Ten bacterial species were identified, with Gram-negative short-rod species such as Escherichia coli, Klebsiella pneumoniae, and Salmonella typhimurium being predominant. HPC values varied from 367 × 10⁴ to 1320 × 10⁴ CFU/mL, with EK2 (2505 × 10⁴ CFU/mL) and EK5 (1320 × 10⁴ CFU/mL) showing particularly high counts. The TCC values ranged from 1049 × 10⁴ to 4400 × 10⁴ CFU/mL, and the FCC values from 130 × 10⁴ to 800 × 10⁴ CFU/mL, all exceeding WHO limits (1.0 × 102 CFU/mL). Historical data show no improvement in water quality, emphasizing the need for individuals to treat water properly before consumption. The findings provide baseline data for local water authorities and serve as a wake-up call for adequate water treatment, storage interventions, and community education on water security. Additionally, this study offers a practical process for improving the quality of water stored in similar regions.

Designing new sulfate ionophores for potentiometric membrane sensors: Selectivity assessment and practical application

Developing potentiometric chemical sensors for sulfate determination is a rather challenging task due to a considerable hydrophilicity of this anion and its poor affinity to lipophilic plasticized polymeric membranes – one of the most popular sensor membrane materials nowadays. Not too many research works were devoted to this problem in the last years. Here we report on the successful development of several novel sulfate ionophores based on the synthetic modification of the commercially available sulfate ionophore I. The newly developed sensors outperform commercial analogue in terms of elelctrochemical sensitivity and selectivity. We have highlighted certain problems with numerical selectivity assessment in case when primary and interfering ions have different charges. The counterintuitive results yielded by conventional selectivity quantification methods implies the relevance of using alternative approach – visualizing sensor response curves towards primary ion in the presence of interfering ions. Novel sulfate sensors were applied for direct potentiometric measurements of sulfate content in river water samples demonstrating real applicability of the developed sensor membranes.

Perfluoroalkyl substances: a risk for the aquatifc environment? A 1-year case study in river waters of central Italy.

Perfluoroalkyl substances (PFASs) are a large class of persistent emerging pollutants, ubiquitous in different environmental compartments. In this study, twenty-one PFASs were determined in seventy-eight water samples collected from six different rivers in the Umbria region (central Italy) during a 13-month monitoring campaign. The sum of the twenty-one target analytes (Σ21PFASs) ranged from 2.0 to 68.5ng L-1, with a mean value of 22.0ng L-1. The highest concentrations of Σ21PFASs were recorded in the warmest months (from June to September) due to reduced river streamflow caused by low rainfall and high temperatures. PFASs with a number of carbon atoms between four and nine prevail over C10-C18 congeners due to their higher water solubility and to their increased use in industry. PFBA, followed by PFPeA, PFHxA, and PFOA, was the most abundant congeners detected in the analyzed river water samples. Finally, the calculation of risk quotients (∑RQs) has allowed to assess the risk for three aquatic organisms (fish, algae, and daphnid) deriving from the exposure to PFASs. The survey showed that the risk for the three aquatic organisms during the four seasons and throughout the year was always negligible. The only exception was a low risk for fish and daphnid in GEN river considering the annual exposure.

Digital One-Step Competitive Detection of a Small Molecule in Synthetic and Environmental Waters.

Optical methods for single-molecule analysis hold the promise of accurate, sensitive, and rapid detection of target molecules. Here, we demonstrate the efficiency of such an approach for the competitive detection of small molecules in water. Our biosensing method is based on a combination of a single-DNA biochip for the parallelization of tethered particle motion real-time measurements with antibodies and modified targets as molecular competitors. The antibodies are coupled to the particles tethered to the surface by a long DNA bearing in its middle the molecular competitor bound to the antibodies. Competitive target binding leads to a detectable conformational change of the DNA tethers from looped to unlooped in proportions related to the target concentration. We thus managed to detect fluorescein, chosen as a model of a target molecule, in freshwater of various qualities, from solutions prepared with ultrapure water to more complex matrices such as river water and wastewater treatment plant effluent samples. Similar dose-response curves were obtained under these various conditions in a wide range of concentrations from nanomolar to micromolar with a limit of detection around 2 nM.