Environmental Water Samples Research Articles

Ultrasensitive electrochemical detection of 4-nitrophenol through flower-like mixed transition metal oxide anchored on reduced graphene oxide composites

4-Nitrophenol or para-nitrophenol is an organic water pollutant that has a direct impact on environmental pollution and human health. Therefore, developing sensitive electrochemical sensors is vital for monitoring environmental water samples to detect hazardous 4-nitrophenol. Herein, template-free zinc vanadate (ZV) micro-flowers were synthesized and anchored on reduced Graphene oxide (RGO) to modify the electrode surface for sensing and quantification of 4-nitrophenol. The fabrication of the as-prepared electrode modifier was confirmed by physicochemical and morphological characterizations. The synthesized ZV/RGO/GCE displayed well-defined reductive peak current at the potential of −0.7 V due to the hydrogenation of 4-nitrophenol. The increase in active sites and the larger surface area acquired by ZV and RGO were responsible for efficient sensing toward 4-nitrophenol. Under the optimized experimental parameters, CV and DPV techniques were carried out to investigate the electrochemical performance of ZV/RGO/GCE for the detection of 4-nitrophenol. The resultant cathodic current response was related linearly (0.01 µM to 1955 µM) to the concentration with the LOD of 0.009 µM. The developed sensor exhibited a good recovery range in the real-sample analysis in multiple water systems. The proposed ZV/RGO/GCE functions well as an effective electrode material for the determination of the perilous pollutant 4-nitrophenol in water samples by an electrochemical approach.

Efficient Solid-Phase Extraction of Neonicotinoid Insecticides from Environmental Water and Drink Samples Using a Postmodified Metal-Organic Framework.

Neonicotinoid insecticides (NNIs) are extensively utilized globally because of their efficient and broad-spectrum properties. However, their residues are also extensively distributed in the environment. Herein, MIL-101-SO3Na with abundant -NH- and sulfonate groups was synthesized via chloromethylation and nucleophilic substitution postmodification strategies and used to extract NNIs via solid-phase extraction. MIL-101-SO3Na was enhanced by introducing C-H···N hydrogen bonds to strengthen interaction forces and -SO3Na groups to adjust surface charge and enhance electrostatic attraction. This modification and the substantial specific surface area (998 m2·g-1) of the metal-organic framework markedly enhanced the enrichment efficiency of MIL-101. The proposed method based on MIL-101-SO3Na exhibited a minimal detection threshold (0.04-0.87 ng·L-1), an extensive linear spectrum (1-2000 ng·L-1), and notable accuracy (a variation of 3.02-11.8%) in water and drink samples. NNI concentrations between 0.25 and 24.2 ng·L-1 in fruit juice and tea samples were accurately identified using the proposed method, demonstrating its feasibility in practical applications. The postmodification of MIL-101-SO3Na is an exceptional and promising approach for the sensitive detection of ultratrace NNI levels in complex matrices.

Development of amphiphilic hypercrosslinked porous polymers for magnetic extraction of multiple environmental pollutants in water

Under the principle of similar compatibility, researchers have developed various polarity extractants corresponding to a class of chemicals. Separating different polarities chemicals with one extractant effectively has become a novel research trend in separation science. Given the complexity of environmental sample matrices and the significant differences in polarity and solubility of various compounds, the introduction of hydrophilic groups to hydrophobic material skeletons can lead to sorbents with hydrophilic-lipophilic balance (HLB) property and thus improve their extraction performance for substances with different polarities. In this work, a hypercrosslinked polymer (HCPPz-TPB), designated as HLB, was synthesized by incorporating polar pyrazine and nonpolar triphenylbenzene molecules within each other. Subsequently, a core-shell magnetic composite material was obtained by encapsulating magnetic Fe3O4 nanoparticles in HCPPz-TPB. The material was applied as an adsorbent for magnetic solid phase extraction (MSPE) and combined with a high-performance liquid chromatography-photodiode array detector (HPLC-PDA) to enrich, separate, and detect seven polar contaminants in environmental water samples. The proposed approach, Fe3O4@SiO2@HCPPz-TPB−MSPE-HPLC-PDA, is characterized by its outstanding high sensitivity, low detection limits, wide linear range, and good reproducibility. The method demonstrated satisfactory linearity in the range of 0.05–2 μg mL-1 with R2 values between 0.9969 and 0.9997; the limits of detection (LOD) were observed to be within the range of 0.0019–0.016 μg L-1, and limits of quantification (LOQ) was observed to be within the range of 0.0064–0.054 μg L-1 range with good precision. The recoveries of the different contaminants in the environmental samples ranged from 83.61 to 116.46% (RSD≤10.56, n = 5). The new hydrophilic-lipophilic balance extractant is highly efficient, sensitive, and precise for extracting different polar pollutants. The findings demonstrate that the Fe3O4@SiO2@HCPPz-TPB display a remarkable affinity for multiple targets, driven by complex interactions including multi-stackings and hydrogen bonding as a sorbent. The synthesized Fe3O4@SiO2@HCPPz-TPB may be employed in diverse applications, including extraction, removal, and determination of diverse trace multi-target analytes in complex media.

Preparation of core-shell magnetic molecularly imprinted polymers on Fe3O4 nanosphere via self-polycondensation for magnetic solid-phase extraction of 2,4-dinitrophenol in environmental water samples

ABSTRACT In this study, a core-shell magnetic molecularly imprinted polymers (MMIPs) adsorbent targeting 2,4-dinitrophenol (2,4-DNP) as a template molecule was developed by surface polymerisation and applied for magnetic solid-phase extraction prior to the determination of 2,4-DNP in environmental water samples via high-performance liquid chromatography. Different experiments were carried out to optimise the magnetic solid-phase extraction conditions. Subsequently, the adsorption capacity and selectivity of prepared MMIPs were investigated. Theoretical analysis demonstrated that the experimental data fitted well to the pseudo-second-order model, suggesting that chemical adsorption might be the rate-limiting step, with a maximum adsorption capacity of 21.76 mg g−1. Under the optimised conditions, this method showed relatively wide linearity within the concentration range of 0.0025 μg·mL−1−0.5 μg·mL−1, with a relative standard deviation of 2.5%–6.2%. The detection limit and quantification limit were 0.23 µg·L−1 and 0.76 µg·L−1, respectively.

Fill, Fold, Photo: Preconcentration and Multiplex Detection of Trace Level Heavy Metals in Water.

Heavy metal contamination is an increasing global threat to human and environmental health, particularly in resource-limited areas. Traditional platforms for heavy metal detection are labor intensive and expensive and require lab facilities. While paper-based colorimetric sensors offer a simpler approach, their sensitivity limitations prevent them from meeting legislative requirements for many metals. Existing preconcentration systems, on the other hand, can achieve lower detection limits but typically focus on analyzing only one metal, making comprehensive monitoring difficult. We address these limitations by introducing a low-cost preconcentration system coupled with colorimetric analysis for the simultaneous detection of seven metal ions at low ppb levels without the need for external equipment outside a smartphone. The system achieved detection limits of 15 ppb (Ni(II)), 7 ppb (Cu(II)), 2 ppb (Fe(III)), 20 ppb (Cr(VI)), 13 ppb (Pb(II)), 26 ppb (Hg(II)), and 15 ppb (Mn(II)) with six out of seven limits of detection values falling well below EPA regulatory guidelines for drinking water. The user-friendly Fill, Fold, Photo approach eliminates complex pretreatment steps. Smartphone-based detection offers portable quantification within seconds. Employing masking strategies ensured higher selectivity for each assay on the card, while our packaging protocols enable system stability for over 4 weeks of study, facilitating mass production and deployment within a realistic time frame. To validate the sensor's performance in real-world scenarios, the sensor was tested with environmental water samples. The sensor demonstrated good recovery, ranging from 77% to 94% compared to the standard ICP-MS method. Furthermore, spike recovery analysis confirmed the sensor's accuracy, with a relative standard deviation (RSD) of less than 15%. This technology holds significant promise for future development as a convenient, portable solution for field-based monitoring of a broad spectrum of water contaminants, including pesticides, PFAS, fertilizers, and beyond.

Comparing the effectiveness of environmental DNA and camera traps for surveying American mink (Neogale vison) in northeastern Indiana.

While camera traps can effectively detect semi-aquatic mammal species, they are also often temporally and monetarily inefficient and have a difficult time detecting smaller bodied, elusive mammals. Recent studies have shown that extracting DNA from environmental samples can be a non-invasive, alternative method of detecting elusive species. Environmental DNA (eDNA) has not yet been used to survey American mink (Neogale vison), a cryptic and understudied North American mustelid. To help determine best survey practices for the species, we compared the effectiveness and efficiency of eDNA and camera traps in surveys for American mink. We used both methods to monitor the shoreline of seven bodies of water in northeastern Indiana from March to May 2021. We extracted DNA from filtered environmental water samples and used quantitative real-time PCR to determine the presence of mink at each site. We used Akaike's Information Criterion to rank probability of detection models with and without survey method as a covariate. We detected mink at four of the seven sites and seven of the 21 total survey weeks using camera traps (probability of detection (ρ) = 0.36). We detected mink at five sites and during five survey weeks using eDNA (ρ = 0.25). However, the highest probability of detection was obtained when both methods were combined, and data were pooled (ρ = 0.47). Survey method did not influence model fit, suggesting no difference in detectability between camera traps and eDNA. Environmental DNA was twice as expensive, but only required a little over half (58%) of the time when compared to camera trapping. We recommend ways in which an improved eDNA methodology may be more cost effective for future studies. For this study, a combination of both methods yielded the highest probability for detecting mink presence.

A simple benzothiazolium-based sensor for cyanide detection: Applications in environmental analysis and bioimaging

A new sensor based on Ethylbenzothiazolium-2-hydroxynaphthaldehyde conjugate-based fluorescent sensor, (E)-3-ethyl-2-(2-(2-hydroxynaphthalen-1-yl) vinyl) benzo[d]thiazol-3-ium iodide (SU-1) was designed and synthesized. The structure of SU-1 was confirmed by 1H NMR, 13C NMR, HRMS, and single crystal XRD spectral analysis. SU-1 displayed a colorimetric and fluorometric response in a DMSO:H2O (1:1,v/v) matrix, changing color from pale yellow to colorless visible to the naked eye, accompanied by a ∼ 120 nm red-shift in the absorption spectra upon CN− addition. This shift, due to formation of deprotonation followed by the nucleophilic attack on the benzothiazolium ring’s double bond, disrupts π-conjugation, blocking intramolecular charge transfer within SU-1. However, competitive anions showed negligible interference while detecting CN−. The Limit of detection for CN− was determined to be 0.27 nM, significantly below the WHO’s permissible CN− concentration in drinking water (1.9 μM). Job’s plot analysis shows that the binding stoichiometry of SU-1 to CN− is a 1:1, with a stability constant (Ka) of 1.58 x 104 M−1. The sensor demonstrated practical applications in environmental water samples and fluorescence imaging of intracellular CN− in CAD cell line.

Adapalene as a chemical sensor for sensitive determination of manganese

ABSTRACT The work describes the use of 6-[3-(1-adamantyl)-4-methoxyphenyl]-2- naphthoic acid, or Adapalene (ADP) as a fluorescence tagging reagent, in a straightforward and very specific spectrofluorometric approach for the trace measurement of manganese (VII) in water. The process is based on the redox interaction of ADP with manganese (VII) in an acidic solution, which forms the complex [Mn (II)-ADP] and causes fluorescence at λex max/λem max = 323/400 nm. High-intensity fluorescence at 400 nm was seen in the fluorescence spectra of the formed complex ion association, Mn (II)-ADP, at pH 4. 1.55 µg mL−1 was the quantification limit, and 0.51 µg mL−1 was the detection limit and the correlation coefficient (R2) was 0.9863. 1.2173 L mol−1 was determined to be the Stern-Volmer. Spectrofluorometric technique is used to validate the approach in environmental water samples, yielding reasonable recovery percentages (89–93%). The current approach is advised to be used for reliable and accurate assessment of manganese (VII) in all wastewater and seawater samples, without the need for complex instrumentation and lengthy procedures.

Approach for concurrent detection and removal of diclofenac in wastewater: Integration of MOF with Poly(deep eutectic solvent) imprinting method

Diclofenac in medical wastewater poses a significant threat to the environment and human health. A simple and efficient enrichment strategy has been established for the selective identification and removal for diclofenac in environmental water samples applying MOF based polymeric deep eutectic solvent (Poly(DES)@MOF). Poly(DES)@MOF was synthesized using a surface imprinting method. The components included MOF-199 as the support material, diclofenac as the template, and a deep eutectic solvent (DES) composed of choline chloride and methacrylate (1:2) as the functional monomer. Density functional theory calculated the Gibbs free energy change during the reaction process, confirming that DES improved the binding performance and selectivity of polymer. Related experiments have shown that Poly (DES) @ MOF has high adsorption capacity, reaching equilibrium within 2 h. In real sample experiments, the maximum adsorption capacity of diclofenac in lake water by the extraction device was 19.39 mg·g−1, with an average recovery rate between 99.4 % and 105.8 %. After 5 repeated uses, the performance did not show significant degradation. After evaluating the principles of green analytical chemistry using agree software, the total score was 0.68, reflecting the high greenness of this study. This study combined molecular imprinting technology and computer theory simulation of MOF based and DES mediated polymerization processes to construct an extraction device that was easy to operate and could extract diclofenac from environmental water samples with high selectivity and adsorption capacity. It showed great potential in the field of environmental monitoring and provided a new approach for the detection of other pollutants in the environment.

Fabrication of Cu-BTC@PW12/GO for multivariate sensing dopamine and acetaminophen as electrochemical sensor

Dopamine (DA) and acetaminophen (AP) are closely associated with many physiological and pathological processes, monitoring their levels precisely is of significance in the early diagnosis of diseases. Herein, a polyoxometalate-based metal-organic framework (POMOF) based on phosphotungstate (Cu-BTC@PW12) was immobilized on graphene oxide (GO) to fabricate Cu-BTC@PW12/GO (CPG) as an electrochemical sensor for the quantification of DA and AP. The spatial confinement effect of copper-based MOF (Cu-BTC) remained the catalytic activity phosphotungstate (PW12) avoiding the aggregation, facilitating electro-catalysis performance for detection of DA and AP. The CPG electrochemical sensor achieved the analysis of DA and AP with the limit of detection (LOD) of 24.8 nM and 62.3 nM, respectively. Furthermore, CPG can be applied for the quantification of DA and AP in real human serum and environmental water samples with satisfied recoveries. Therefore, this work expanded the utilization of POMOF in electrochemical analysis and has promising prospects for the early diagnosis of diseases and environmental treatment.

β-cyclodextrin-modulated ratiometric supramolecular BODIPY fluoroprobe for highly selective and sensitive detection of thiophenol

Thiophenol (PhSH) is an important industrial intermediate but displays significant toxicity towards environmental and biological systems. Here, we introduce a supramolecular system based on β-cyclodextrin (β-CD) and boron dipyrromethene (BODIPY) as a ratiometric fluorescence probe to discriminate PhSH in environmental water samples, cells, and in vivo. In aqueous solutions, BODIPY shows extremely weak fluorescence intensity due to its aggregation into nanometer-sized clusters, which prevents its interaction with thiols. However, within a β-CD environment, it can selectively and sensitively detect PhSH. Also, the stability of the probe was significantly improved. The mechanism studies based on stoichiometry, NMR spectroscopy, and theoretical calculation revealed distinct intermolecular interactions between β-CD and BODIPY, including host-guest interactions and hydrogen bonds. Low limit of detection (10.7 nM) and rapid response time (5 min) have been achieved, and the practicality of the supramolecular system (BODIPY@β-CD) has been verified by actual sample analysis. Furthermore, the first hydrogel-based sensing system for portable PhSH detection has been developed, facilitating rapid and on-site colorimetric visualization across both liquid and gas phases. Most importantly, using a low amount of the probe, early stages of low-dose exposure to PhSH can be visualized in living cells and zebrafish. Therefore, BODIPY@β-CD is a robust new monitoring tool for the detection of PhSH in various scenarios, indicating the promising application value of the host-guest supramolecular probe in detecting highly toxic substances.

A multi-dimensional anti-counterfeiting nanocomposite based on fluorescent CDs and Eu-MOFs with dual function for continuous detection of Cu2+ and Bacillus anthracis

Traditional luminescent materials for anti-counterfeiting usually adopt encryption of low-level systems with limited security, which seriously hinders their application in preventing counterfeiting and information leakage. Therefore, it is urgent to develop materials for higher-level anti-counterfeiting. In this work, a stimulus-responsive intelligent luminescent material (AC@CDs-Eu-MOFs) was prepared by co-loading green-fluorescence CDs and red-fluorescence Eu-MOFs on Amino clay (AC). 5D security barcodes, which were easy to observe while difficult to clone, were ulteriorly designed based on the nanocomposite owing to the tunable fluorescence by optical stimulation and chemical stimulus. Owing to the large capacity, low cost, and easy authentication, the 5D security barcodes possess enormous potential in optical data storage and multi-dimensional information encryption. In addition, the chemical stimulus-response enables the nanocomposite achievable in detection of Cu2+ and Bacillus anthracis. Particularly, quantitative determination of copper in environmental water samples could be realized with a detection limit as low as 10.67 nM. Therefore, the material shows potential for detection of environmental pollutants besides advanced anti-counterfeiting.

Ionic Liquid-Solidified Floating Organic Drop Microextraction for the Preconcentration of Lead in Environmental Water Samples Prior to Its Determination with Electrothermal Atomic Absorption Spectrometry.

This research investigates the utilization of an ionic liquid combination of solidified floating organic drop micro-extraction (IL-SFODME) to augment the concentration of trace amounts of lead, working as a preliminary stage before electrothermal atomic absorption spectrometry (ETAAS) analysis without the use of chelating agents. Key parameters impacting the microextraction efficiency-including pH, the volume of the ionic liquid (1-Hexyl-3-methylimidazolium hexafluorophosphate, HMIMPF6), temperature, extraction time, and stirring speed-were methodically examined to determine optimal conditions. Under detected optimized conditions, an enhancement factor of 71.2 was obtained for a 15 mL sample solution. The calibration curve exhibited linearity within the concentration range of 0.2-2.5 µg/L, with a detection limit (3σ) of 0.054 µg/L and a quantification limit (10σ) of 0.18 µg/L. For seven replicate measurements of 0.5 µg/L lead, the relative standard deviation (RSD) was ±2.30%. This method was effectively implemented to extract and quantify lead in both reference water and different real water samples, showcasing significantly efficient extraction performance.

Monomer-mediated growth of β-cyclodextrin-based microporous organic network as stationary phase for capillary electrochromatography.

CD-MONs (β-cyclodextrin-based microporous organic networks), derived from β-cyclodextrin, possess notable hydrophobic characteristics, a considerable specific surface area, and remarkable stability, rendering them highly advantageous in separation science. This research aimed to investigate the utility of CD-MONs in chromatography separation. Through a monomer-mediated technique, we fabricated an innovative CD-MON modified capillary column for application in open-tubular capillary electrochromatography (OT-CEC). The CD-MON-based stationary phase on the capillary's inner surface was analyzed using Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). We assessed the performance of the CD-MON modified capillary column for separation purposes. The microstructure and pronounced hydrophobicity of CD-MON contributed to enhanced selectivity and resolution in separating diverse hydrophobic analytes, such as alkylbenzenes, halogenated benzenes, parabens, and polycyclic aromatic hydrocarbons (PAHs). The maximum column efficiency achieved was 1.5 × 105 N/m. Additionally, the CD-MON modified capillary column demonstrated notably high column capacity, with a methylbenzene mass loading capacity of up to 197.9pmol, surpassing that of previously reported porous-material-based capillaries. Furthermore, this self-constructed column was effectively utilized for PAHs determination in actual environmental water samples, exhibiting spiked recoveries ranging from 93.2 to 107.9% in lake water samples. These findings underscore the potential of CD-MON as an effective stationary phase in separation science.

Rapid and Cost‐Effective Platypus eDNA Detection in Waterways Using Loop‐Mediated Isothermal Amplification Assay: Advancing Conservation Efforts

ABSTRACTFreshwater ecosystems, home to a remarkable diversity of species, are facing severe threats from human activities such as climate change, habitat degradation, over‐extraction of water for irrigation, and pollution. The platypus, an iconic species in freshwater ecosystems around Australia, is threatened by all these activities, both singly and in combination. The scale and complexity of these intersecting and reinforcing threats makes cost‐effective monitoring tools essential to better understand how platypus populations are responding. In this study, we optimized a loop‐mediated isothermal amplification (LAMP) assay for the rapid and cost‐effective detection of platypus DNA in environmental water samples, offering an attractive alternative to quantitative polymerase chain reaction (qPCR). We improved a water filtration protocol for in‐field use, employing suitable filter membranes for processing large volumes of water, thereby maximizing DNA recovery from dilute samples. The limit of detection for the platypus LAMP (Plat‐LAMP) assay was determined to be 12.4 copies/μL using a standard plasmid positive reference and 7 × 10−6 ng/μL when applied to DNA extracted from platypus tissue, with improved sensitivity achieved through the incorporation of locked nucleic acid primers. In comparative testing against qPCR, the Plat‐LAMP assay exhibited greater sensitivity in detecting platypus DNA in known positive water samples collected from platypus habitat at Healesville Sanctuary. Furthermore, the Plat‐LAMP assay demonstrated 100% specificity when performed on water samples collected from non‐platypus habitats. In field testing across waterways in Victoria and New South Wales, the Plat‐LAMP assay detected platypus in 36.96% of samples, compared to 54.35% of samples using qPCR. These findings underscore the Plat‐LAMP assay's potential as a faster and more cost‐effective complementary method to qPCR, rendering it suitable for point‐of‐application water testing. The ability to conduct eDNA surveys without the need for cold‐chain logistics would significantly assist conservation organizations and water managers map platypus distributions and facilitate conservation efforts around Australia.

Design of Selective Nanoparticles of Layered Double Hydroxide (Mg/Al-LDH) for the Analysis of Anti-Inflammatory Non-Steroidal Agents in Environmental Samples, Coupled with Solid-Phase Extraction and Capillary Electrophoresis

A simple, fast, and low-cost pre-concentration methodology based on the application of solid-phase extraction coupled to layered double hydroxides (LDHs) and capillary electrophoresis was developed for the determination of naproxen (NPX), diclofenac (DFC), and ibuprofen (IBP) in environmental sample waters. A systematic study of the LDH composition was designed, including the effects of interlayer anions (NO3−, Cl−, CO32−, BenO−, and SDS−) and the effect of molar ratio (Mg:Al). The optimal composition of MgAl/Cl−-LDH (Mg:Al; 1.5:1.0) was coupled to an SPE system: pH (neutral pH), LDH amount (15 mg), and extraction capacity ranged from 79.71 to 83.11% for the three anti-inflammatory non-steroidal agents analyzed. A recovery rate of up to 80.87% was obtained when 0.01 M chloride acid in methanol was used as the eluent and 50 mL of sample was used. Under optimal conditions, the linear range of the calibration curve ranges from 18.02 to 200 μg L−1, with limits of detection ranging from 6.03 to 18.02 μg L−1 for the three NSAIDs. The precision of the methodology was evaluated in terms of inter- and intra-day repeatability, with %RSD < 10% in all cases. The proposed method was applied to analyze environmental water samples (bottle, tap, cistern, well, and river water samples). The developed method is a robust technique capable of combining with other analytical methods to quantitatively determine anti-inflammatory non-steroidal agents.

Silicon quantum dots based fluorescent probes for detecting methyl parathion pesticide residues in potato, tap water and Yellow River

In this paper, a novel ratiometric fluorescent probe based on silicon quantum dots (SiQDs) has been developed for the sensitive detection of methyl parathion pesticide residues. The silicon quantum dots were prepared by a simple hydrothermal reaction process using 3-Aminopropyltriethoxysilane (APTES) as silicon resource and were characterized by the analysis of transmission electron microscopy, FTIR spectroscopy, and X-ray photoelectron spectroscopy. The silicon quantum dots displayed characteristic blue fluorescence emission at 440 nm. Tyrosinase can catalyze the oxidation of tyramine to form dopamine. Then, dopamine can interact with silicon quantum dots and effectively change the position of its fluorescence emission for redshiftting to 540 nm. In the presence of organic phosphorus pesticides (OPPs), the activity of tyrosinase was inhibited, resulting in the inability to generate dopamine and the fluorescence emission at 440 nm remaining unchanged. As a model of organic phosphorus pesticides, methyl parathion (MP) was determined using this method, and the fluorescence intensity response values showed a good linear relationship with methyl parathion concentration in the range of 50–90 nM, with a detection limit of 0.149 nM. Due to its good performance of relative low detection limit, good selectivity and high reproducibility, this sensing system has been successfully applied to the detection of methyl parathion in environmental water samples and potato samples, which showed good prospects for application in the detection of organic phosphorus pesticide residues in more real samples.

All-Solid-State PVC-Membrane Cu(II)-Selective Potentiometric Microsensor Based on a Novel Calix[4]arene Derivative

In this study, 25,27-dihydroxy-26,28-bis(ethoxycarbonylbutyoxy)-5,11,17,23-p-tert-butylcalix[4]arene was used as an ionophore for the preparation of a novel all-solid-state type microsensor to make a selective potentiometric response towards Cu(II) ions. The optimum membrane composition of the microsensor was determined as 2% (w/w) ionophore, 67% (w/w) bis (2-ethylhexyl) sebacate (DOS), 30% (w/w) polyvinylchloride (PVC), and 1%(w/w) potassium tetrakis 4-chlorophenyl borate (KTpClPB). The Cu(II)-selective microsensor exhibited a highly selective Nernstian response of 31.3±2.1 mV slope (R2: 0.997) with a short response time (15 s) over the concentration range of 10−5 to 10−1 mol L−1 of Cu(II) ions for 8 weeks with no significant difference in potentials. The microsensor was effectively performed in the pH range of 5.0–8.0, with low detection limit as 7.63×10−7 mol L−1, and a temperature range of 15−40 °C. The prepared microsensor was successfully used both as an indicator electrode in the potentiometric titration of Cu(II) ions with EDTA and also in the determination of the Cu(II) content of environmental water samples. When the potentiometric results were compared with ICP-OES, they were found to be in good agreement with ICP-OES results at a 95% confidence level.

Ultrasound assisted upper critical solution temperature type switchable deep eutectic solvent based liquid-liquid microextraction for the determination of triazole in water

BackgroundThe use of pesticides to protect crops has long been an important measure to provide healthy and safe agricultural products, but excess pesticides flow into fields and rivers, causing environmental pollution. Earlier methods utilizing organic solvent liquid-liquid microextraction for pesticide residue detection were not environmentally friendly. Therefore, it is significant to find a greener and more convenient detection method to determine pesticide residues. ResultsA new method was established to detect three triazole fungicides (TFs), including myclobutanil, epoxiconazole and tebuconazole, in environmental water samples. And the determination was conducted using a high-performance liquid chromatography with the ultraviolet detector (HPLC-UV). The switchable deep eutectic solvent (SDES) can be reversibly switched between hydrophilic and hydrophobic states through temperature modulation. Additionally, the method exhibited excellent linearity for all target analytes within the concentration range of 10–2000 μg L−1, with satisfactory R2 values (≥0.9975). The limits of detection (LODs) ranged from 2.3 to 2.6 μg L−1, and the limits of quantification (LOQs) ranged from 7.8 to 8.7 μg L−1. The accuracy of the method was assessed through intra-day and inter-day precision tests, yielding relative standard deviations (RSDs) in the ranges of 2.8%–6.7% and 2.2%–7.5%, respectively. Density functional theory (DFT) results indicated that hydrogen bonding is a significant factor affecting the binding of DES with triazoles. Three different green assessment tools were used to prove that the SDES-HLLME method had good greenness and broad applicability. SignificanceThis is a homogeneous liquid-liquid microextraction (HLLME) method based on the upper critical solution temperature (UCST) type switchable deep eutectic solvent program, which can complete the extraction within a few minutes without dispersant. In terms of pesticide detection, the analytical method is simple and more conducive to environmental protection.

Facile Preparation of Tannic Acid-Gold Nanoparticles for Catalytic and Selective Detection of Mercury(II) and Iron(II) Ions in the Environmental Water Samples and Commercial Iron Supplement.

Tannic acid (TA), a plant-derived polyphenol rich in hydroxyl groups, serves as both a reducing agent and stabilizer for synthesizing gold nanoparticles (TA-AuNPs). This study presents a groundbreaking method that utilizes TA to fabricate TA-AuNPs and develop two distinct colorimetric detection systems for mercury (Hg2+) and iron (Fe2+) ions. The first detection system leverages the interaction between TA-AuNPs and Hg2+ to enhance the peroxidase-like activity of TA-AuNPs, facilitating the production of hydroxyl radicals upon reaction with hydrogen peroxide, which subsequently oxidizes 3,3',5,5'-tetramethylbenzidine (TMB) into a blue-colored product (ox-TMB). The second system capitalizes on TA-AuNPs to catalyze the Fenton reaction between Fe2+ and hydrogen peroxide in the presence of 2, 6-pyridinedicarboxylic acid, boosting the generation of hydroxyl radicals that oxidize TMB into a blue-colored ox-TMB. Absorbance measurements at 650 nm display a linear relationship with Hg2+ concentrations ranging from 0.40 to 0.60 μM (R2 = 0.99) and Fe2+ concentrations from 0.25 to 2.0 μM (R2 = 0.98). The established detection limits for Hg2+ and Fe2+ are 18 nM and 96 nM, respectively. Applications to real-world samples achieved an excellent spiked recovery, spanning 101.6% to 108.0% for Hg2+ and 90.0% to 112.5% for Fe2+, demonstrating the method's superior simplicity, speed, and cost-effectiveness for environmental monitoring of these ions compared to existing techniques.