Aqueous Environmental Samples Research Articles

A “turn-on” fluorescent sensor for Pb2+ detection based on nitrogen doping carbon dots

Nitrogen-doped carbon dots (N-CDs) were synthesized via a green chemistry route and subsequently employed as a fluorescent sensing probe for Pb2+ ions. Through a series of characterizations, the properties of the obtained N-CDs were comprehensively deciphered and investigated. In particular, the specific fluorescence response for Pb2+ was obviously promoted by a “turn-on” mode, even in the presence of other interfering metal ions. According to the established N-CDs sensors, a linear correlation of fluorescence intensity and Pb2+ concentration was formed in the range of 0∼50 μM. This sensing platform displayed a sensitive and selective detection towards Pb2+ ions, in which a limit of detection (LOD) was achieved up to 0.92 μM. Finally, the underlying sensing mechanism towards Pb2+ was proposed by a photo-induced electron transfer (PET) inhibition process, which was demonstrated by a density functional theory (DFT) simulation study. This work provides a promising platform for the analysis of Pb2+ ions in aqueous environmental samples.

Selective fluorescent probe for sensitive determination of bisphenol A based on molecularly imprinted polymers decorated carbon dots derived from citric acid and ethylenediamine

Bisphenol A (BPA) is an endocrine disrupting chemical and poses a grave threat to the human health. Herein, a fluorescent probe constructed with molecularly imprinted polymers decorated carbon dots (CDs@MIPs) was proposed for determination of BPA with high selectivity. The CDs@MIPs were constructed using BPA, 4-vinylpyridine and ethylene glycol dimethacrylate as template, functional monomer and cross linker, respectively. The obtained fluorescent probe not only owned a highly selective recognition function derived from MIPs but also displayed an excellent sensitivity for sensing BPA stemmed from CDs. The fluorescence intensity of CDs@MIPs was varied before and after the removal of BPA templates. The fluorescent decrease fraction of the fluorescent probe demonstrates a nice linearity in BPA concentration range of 10–2000 nM (r2 = 0.9998) and the detection limit is as low as 1.5 nM. The fluorescent probe was triumphantly utilized to sense the level of BPA in real aqueous and plastic samples with good results. Moreover, the fluorescent probe offered a wonderful means for fast identification and sensitive detection of BPA from environmental aqueous samples.

Bioaccumulation Behavior and Human Health Risk of Polybrominated Diphenyl Ethers in a Freshwater Food Web of Typical Shallow Lake, Yangtze River Delta.

Polybrominated diphenyl ethers (PBDEs) have been commonly found in aquatic ecosystems. Many studies have elucidated the bioaccumulation and biomagnification of PBDEs in seas and lakes, yet few have comprehensively evaluated the bioaccumulation, biomagnification, and health risks of PBDEs in shallow lakes, and there is still limited knowledge of the overall effects of biomagnification and the health risks to aquatic organisms. In this study, a total of 154 samples of wild aquatic organism and environmental samples were collected from typical shallow lakes located in the Yangtze River Delta in January 2020. The concentrations of PBDEs were determined by an Agilent 7890 gas chromatograph coupled and an Agilent 5795 mass spectrometer (GC/MS) and the bioaccumulation behavior of PBDEs was evaluated in 23 aquatic organisms collected from typical shallow lakes of the Yangtze River Delta. Furthermore, their effects on human health were evaluated by the estimated daily intake (EDI), noncarcinogenic risk, and carcinogenic risk. The concentrations of ΣPBDE (defined as the sum of BDE-28, -47, -100, -99, -153, -154, -183, and -209) in biota samples ranged from 2.36 to 85.81 ng/g lipid weight. BDE-209, BDE-153 and BDE-47 were the major PBDE congeners. The factors affecting the concentration of PBDEs in aquatic organisms included dietary habits, species, and the metabolic debromination ability of the PBDE congeners. BDE-209 and BDE-47 were the strongest bioaccumulative PBDE congeners in aquatic organisms. Additionally, except for BDE-99, BDE-153 and BDE-154, the trophic magnification factor (TMF) values of PBDE congeners were significantly higher than 1. Moreover, the log Kow played a significant role in the biomagnification ability of PBDE congeners. The noncarcinogenic risk of PBDE congeners and carcinogenic risk of BDE-209 from aquatic products were lower than the thresholds. PBDE congeners were bioaccumulated and biomagnified to varying degrees in aquatic organisms from typical shallow lakes. Both the noncarcinogenic and carcinogenic risks assessment of edible aquatic products indicated that none of the PBDE congeners pose health risks to the localite. This study will provide a basis for a comprehensive assessment of PBDEs in aquatic ecosystems in shallow lakes and for environmental prevention measures for decision-makers.

Dual-mode strategy for 2,6-dipicolinic acid detection based on the fluorescence property and peroxidase-like activity inhibition of Fe-MIL-88NH2

This work designed a fluorometric/colorimetric dual-mode sensor for detecting 2,6-dipicolinic acid (DPA) based on the blue emission property and peroxidase-like activity of Fe-MIL-88NH2. The fluorescence of Fe-MIL-88NH2 was obviously turned off by Cu2+, but DPA was able to bring it back because it has a strong chelate bond with Cu2+. Fe-MIL-88NH2 also displayed high peroxidase-like activity, which accelerated the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to the blue oxidation product (oxTMB) when H2O2 was present. When DPA was added, it efficiently inhibited the peroxidase-like activity of Fe-MIL-88NH2, causing less oxTMB and less absorbance at 652 nm. The fluorescence recovery of Fe-MIL-88NH2 and the change in absorbance at 652 nm were used as analytical signals for dual-mode detection of DPA. The linear responses in the range of 10–60 μM and 60–160 μM were achieved for the fluorometric mode, and the limit of detection (LOD) was 1.46 μM. The respective values of linear range and LOD for the colorimetric mode were 5–25 μM and 3.00 μM, respectively. In summary, the dual-mode testing strategy successfully detected DPA in aqueous environmental samples, suggesting great potential in disease prevention and environmental analysis.

Enhancing catalytic activity through the construction of praseodymium tungstate decorated on hierarchical three-dimensional porous biocarbon for determination of furazolidone in aquatic samples

Boosting catalytic performance as a vital role for an electrochemical sensor for monitoring various hazardous nitro drugs. Herein, an inexpensive, facile, and eco-friendly construction of praseodymium tungstate decorated on three dimensional porous biocarbon (PrW/3D-PBC) for electrochemical determination of carcinogenic residue furazolidone (FZ). The nanostructured PrW nanoparticles were prepared by solvent evaporation from peroxo-tungstic acid and 3D-PBC was prepared from biomass precursor under the carbonization method. Furthermore, the composite of PrW decorated on 3D-PBC was prepared by an ultrasonic-assisted wet chemical approach. Besides, the composite characterization of crystalline, functional group, degree of carbonization, chemical states, and morphology were utilized by theXRD, FTIR, RAMAN, XPS, and FESEM analysis. These 3D porous carbon decorated PrW nanoparticles facilitate the electrochemical anchoring sites, surface area, and ease of diffusion layers towards the detection of hazardous nitro pollutant FZ by using CV analysis. The low LOD and high sensitivity were achieved by FZ determination through using LSV and DPV techniques. The practical capability of the PrW/3D-PBC/GCE sensor was determined by using aquatic samples to achieve a good recovery result. These results instigate that the PrW/3D-PBC will be an efficient electrocatalytic material for FZ sensor in environmental aquatic samples.

Interactions of natural colloids with microplastics in aquatic environment and its impact on FTIR characterization of polyethylene and polystyrene microplastics

The demand for plastics is expected to rise due to the exponential growth of the manufacturing sector. The plastic industries get subsidies from Governments to boost foreign exchange. The mismanagement of plastic waste has contaminated water bodies with macro, micro, and nano plastics ultimately causing varied toxicological impairment to the aquatic and terrestrial environments. We have investigated the interaction of polystyrene (PS) and polyethylene (PE) microplastics with the natural colloids in waters. Eco-corona formation due to adsorption of colloids and dissolved contaminants on the microplastic’s surface was observed upon suspending PS and PE microplastics in natural marine and freshwater tagged with 2 µg ml−1 acridine orange. Fourier transform infrared spectroscopy (FTIR) studies revealed a diminishing intensity in the characteristic peaks of the and the disappearance of minor vibrations in IR spectra of the polymers upon suspension in natural waters for over 40 days. The alterations in the peaks were restored, and PE was recovered upon treatment with 30 % hydrogen peroxide (H2O2). In contrast, the recovery of PS was only partial, denoting the strong interactions of PS with natural colloids. The active groups on the polymer structure interacting with the colloids creates an eco-corona layer absorbing the light. The ecocorona formation hinders light transmission and detection by analytical methods such as FTIR, thereby substantiating the lower quantities of PS isolated and detected from aquatic animals and environmental samples. Eco-coronated microplastics could mimic the natural feed for small fishes and lower marine animals, facilitating their uptake and further transfer across the aquatic food web.

Modulated covalent organic frameworks with higher specific surface area for the ultrasensitive detection of polybrominated biphenyls

Controllable construction of covalent organic frameworks (COFs) is fascinating, and full elucidations on the relationships between their microstructures and adsorption performance for persistent organic pollutants (POPs) are imperative and desirable, yet challenging. Herein, the 2,5-dimethoxybenzaldehyde (DB) has been first employed as a modulator to construct COFs with higher specific surface area and enhanced hydrophobicity under the mild conditions, after competing with the building blocks of 2,5-dimethoxyterephaldehyde (DMTP) and 1,3,5-tris(4-aminophenyl)benzene (TAPB). These TAPB-DMTP-DB COFs have been further fabricated as solid phase microextraction (SPME) coatings with uniform morphology and comparative thickness, to investigate their enrichment capacities for POPs systematically. In particular, the DB-modulated COF demonstrated outstanding enrichment factors (4400–11360) for polybrominated biphenyls (PBBs). Moreover, ultrasensitive analytical method has been developed based on the DB-modulated COF-coated fiber and gas chromatography-mass spectrometry (GC–MS), with low limits of detection (0.04–0.28 ng/L), wide linear range (0.25–5000 ng/L), and satisfactory reproducibility, realizing the precise quantifications of ultra-trace PBBs in environmental aqueous samples.

An amperometric electrochemical sensor based on hierarchical dual- microporous structure polypyrrole nanoparticles for determination of pyrogallol in the aquatic environmental samples

Pyrogallol (PY) is commonly found as inherent toxicity of industrial effluents which easily enter to the aquatic environment; owing to its oxygen free radicals which causes several health issues. We report a highly sensitive and selective pyrogallol (PY) sensor using hierarchical dual-microporous polypyrrole nanoparticle-modified screen-printed carbon electrode (MPNPs/SPCE). The proposed electrode material for the cost-effective and rapid estimation of PY in the environmental water samples. Hierarchical dual-microporous polypyrrole nanoparticles were prepared through the simple chemical polymerization of pyrrole using Pluronic F-127 as the surfactant. The MPNPs possess well-defined dual micropore (∼0.52 and ∼ 0.67 nm) and a large BET surface area (183 m2/g). The electro-oxidation behavior of PY was examined by cyclic voltammetry and amperometric technique. Hierarchical structure with dual-microporous networks, and large specific surface area of MPNPs were assumed to be greatly enhanced the adsorption rate and a fast facilitate ion transfer for PY sensor. Owing to the effective coupling of hydrogen bonding (interaction between –OH group of PY and –NH group of polymer chain) and π -π interactions (between PPy rings and the PY aromatic rings) can offer more accessible electrochemical active sites and electrolyte/electrode contact interfaces for rapid electro-oxidation response. As a result, wide linear range (0.05–130 μM), good detection limit (0.03 μM), and high sensitivity (1.213 μA μM−1 cm−2) toward PY surpass those of other modified electrodes. Furthermore, MPNPs/SPCE system exhibited desirable selectivities, good steady stabilities, and reproducibilities as PY sensors. Real domestic, industrial, and sewage environmental water samples were analyzed, with quantification data compared with those obtained by HPLC.

Novel diaminoguanidine functionalized cellulose: synthesis, characterization, adsorption characteristics and application for ICP-AES determination of copper(II), mercury(II), lead(II) and cadmium(II) from aqueous solutions

In this study, the novel adsorbent diaminoguanidine-modified cellulose (DiGu.MC) was synthesized to extract mercury, copper, lead and cadmium ions from aqueous solutions and environmental water samples. The synthetic strategy involved oxidizing cellulose powder into dialdehyde cellulose (DAC) and reacting DAC with diaminoguanidine to create an imine linkage between the two reactants to form diaminoguanidine-modified cellulose (DiGu.MC). The structure and morphology of the adsorbent were studied using a variety of analytical techniques including Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area measurements. Adsorption of mercury, copper, lead, and cadmium ions was optimized by examining the effects of pH, initial concentration, contact time, dose, temperature and competing ions. Under optimal adsorption conditions, the adsorption capacities of Cu2+, Hg2+, Pb2+, and Cd2+ were 66, 55, 70 and 41 mg g−1, respectively. The adsorption isotherm is in very good agreement with the Langmuir isotherm model, indicating that a monomolecular layer is formed on the surface of DiGu.MC. The kinetics of adsorption are in good agreement with the pseudo-second kinetics model that proposes the chemical adsorption of metal ions via the nitrogen functional groups of the adsorbent. Thermodynamic studies have confirmed that the adsorption of heavy metals by DiGu.MC is exothermic and spontaneous. Regeneration studies have shown that the adsorbent can be recycled multiple times by removing metal ions with 0.2 M nitric acid. The removal efficiency for regeneration was over 99%. DiGu.MC is introduced as a unique adsorbent in removing mercury, copper, lead and cadmium with a simple synthetic strategy, with cheap starting materials, a unique chemical structure and fast adsorption kinetics leading to excellent removal efficiency and excellent regeneration. The mechanism of adsorption of the investigated heavy metals, is probably based on the chelation between the metal ions and the N donors of DiCu.MC.

Mechanochemically synthesized zeolitic imidazolate framework-8 as sorbent for dispersive solid-phase extraction of benzophenone-type ultraviolet filters in aqueous samples

Benzophenone-type ultraviolet filters (BP-UVFs) are a group of emerging contaminants, which found in various environmental aqueous samples raising potential risks for public health concern and could bioaccumulate in the food chain. This study describes a simple and “green” method to rapidly analyze five BP-UVFs that are frequently found in surface water and in seawater samples. Dispersive solid-phase extraction (DSPE) using a zeolitic imidazolate framework‑8 (ZIF-8) as the sorbent was applied to efficiently extract the BP-UVFs from aqueous samples, and they were then detected and quantified by UHPLC-electrospray ionization (+)-quadrupole time-of-flight mass spectrometry (UHPLC-ESI (+)-QTOF-MS). The ZIF-8 sorbent was synthesized by a green one-step mechanochemical process using water-assisted grinding and a stoichiometric reaction. The Box-Behnken Design coupled with the response surface method was applied to optimize the main DSPE extraction factors. The developed method was fully validated, showing low limits of quantification (LOQs; 0.3−20 ng L−1), satisfactory mean spiked recoveries (72−105%), and a high level of precision (3−9%). A preliminary analysis of the surface water and seawater samples revealed that 2-hydroxy-4-methoxybenzophenone (BP-3) was the most common BP-UVF present in our aquatic environment, likely due to its widespread applications and slow rate of degradation.

Sulfur-doped graphitic carbon nitride nanosheets as a sensitive fluorescent probe for detecting environmental and intracellular Ag+

Silver is widely used in medical materials, photography, electronics and other industries as a precious metal. The large-scale industrial production of silver-containing products and liquid waste emissions aggravate the environmental pollution. Silver ion is one of the most toxic metal ions, causing pollution to the environment and damage to public health. Therefore, the efficient and sensitive detection of Ag+ in the water environment is extremely important. Sulfur-doped carbon nitride nanosheets (SCN Ns) were prepared by melamine and thiourea via high-temperature calcination. The morphology, chemical composition and surface functional groups of the SCN Ns were characterized by SEM, TEM, XRD, XPS, and FT-IR. The fluorescence of SCN Ns was gradually quenched as the Ag+ concentration increased. The detection limit for Ag+ was as low as 0.28 nM. The quenching mechanism mainly is attributed to static quenching. In this paper, SCN Ns were used as the fluorescent probe for detecting Ag+. SCN Ns have successfully detected Ag+ in different environmental aqueous samples and cells. Finally, SCN Ns were further applied to the visual quantitative detection of intracellular Ag+.

Viral Eco-Genomic Tools: Development and Implementation for Aquatic Biomonitoring.

Enteric viruses (EVs) occurrence within aquatic environments varies and leads to significant risk on public health of humans, animals, and diversity of aquatic taxa. Early and efficacious recognition of cultivable and fastidious EVs in aquatic systems are important to ensure the sanitary level of aquatic water and implement required treatment strategies. Herein, we provided a comprehensive overview of the conventional and up-to-date eco-genomic tools for aquatic biomonitoring of EVs, aiming to develop better water pollution monitoring tools. In combination with bioinformatics techniques, genetic tools including cloning sequencing analysis, DNA microarray, next-generation sequencing (NGS), and metagenomic sequencing technologies are implemented to make informed decisions about the global burden of waterborne EVs-associated diseases. The data presented in this review are helpful to recommend that: (1) Each viral pollution detection method has its own merits and demerits; therefore, it would be advantageous for viral pollution evaluation to be integrated as a complementary platform. (2) The total viral genome pool extracted from aquatic environmental samples is a real reflection of pollution status of the aquatic eco-systems; therefore, it is recommended to conduct regular sampling through the year to establish an updated monitoring system for EVs, and quantify viral peak concentrations, viral typing, and genotyping. (3) Despite that conventional detection methods are cheaper, it is highly recommended to implement molecular-based technologies to complement aquatic ecosystems biomonitoring due to numerous advantages including high-throughput capability. (4) Continuous implementation of the eco-genetic detection tools for monitoring the EVs in aquatic ecosystems is recommended.

Preparation of monolith-based adsorbent containing abundant functional groups for field entrapment of nitrogen and sulfur containing aromatic compounds in environmental aqueous samples with portable multichannel in-tip microextraction device

Field sample preparation is important and interesting for analysis of nitrogen and sulfur containing aromatic compounds (N,S-CACs) in environmental aqueous samples. In this connection, a new functional groups-rich adsorbent based on porous monolith (ABM) was fabricated by in-situ copolymerization of allylaminocarbonylphenyl boronic acid/styrene and ethylene glycol dimethacrylate. The prepared ABM was employed as the extraction medium of homemade portable multichannel in-tip microextraction device (PMMD) for on-site entrapment of N,S-CACs in various waters. Because of the abundant functional groups, the obtained ABM/PMMD exhibited satisfactory capture capability towards studied N,S-CACs, and the enrichment factors varied from 454 to 491. Under the optimized fabrication conditions, adsorption and desorption parameters, the developed ABM/PMMD was used to field capture investigated N,S-CACs and followed by quantification with high performance liquid chromatography. The limits of detection were in the ranges of 0.00030–0.0016 µg/L. Recoveries with low, medium and high spiked contents located in the range of 82.1–118% with good repeatability (RSDs<9%). In addition, traditional laboratory sample pretreatment approach was employed to verify the reliability of the established method. Results well evidenced that the practicability of introduced ABM/PMMD in the field sample preparation of N,S-CACs in environmental waters.

Speciation of inorganic arsenic in aqueous samples using a novel hydride generation microfluidic paper-based analytical device (µPAD)

The development of the first microfluidic paper-based analytical device (µPAD) for the speciation of inorganic arsenic in environmental aqueous samples as arsenite (As(III)) and arsenate (As(V)) which implements hydride generation on a paper platform is described. The newly developed µPAD has a 3D configuration and uses Au(III) chloride as the detection reagent. Sodium borohydride is used to generate arsine in the device’s sample zone by reducing As(III) in the presence of hydrochloric acid or both As(III) and As(V) (total inorganic As) in the presence of sulfuric acid. Arsine then diffuses across a hydrophobic porous polytetrafluoroethylene membrane into the device’s detection zone where it reduces Au(III) to Au nanoparticles. This results in a color change which can be related to the concentration of As(III) or total inorganic As (i.e., As(III) and As(V)) concentration. Under optimal conditions, the µPAD is characterized by a limit of detection of 0.43 mg L−1 for total inorganic As (As(III) + As(V)) and 0.41 mg L−1 for As(III) and a linear calibration range in both cases of 1.2–8.0 mg As L−1. The newly developed µPAD-based method was validated by applying it to groundwater and freshwater samples and comparing the results with those obtained by conventional atomic spectrometric techniques.Graphical abstract

A two-dimensional nanoparticle characterization method combining differential mobility analyzer and single-particle inductively coupled plasma-mass spectrometry with an atomizer-enabled sample introduction (ATM-DMA-spICP-MS): Toward the analysis of heteroaggregated nanoparticles in wastewater

Characterizing engineered nanoparticles (ENPs) in complex environmental matrices remains a challenging task. This work presents a two-dimensional size analysis method by combining differential mobility analyzer (DMA) and single-particle inductively coupled plasma-mass spectrometry (spICP-MS) with a new atomizer (ATM)-enabled sample introduction that is relatively easy to operate. The tailing of electrical mobility size distributions was solved by heating the aerosol flow, where water-shelled gold nanoparticles (AuNPs) were dehydrated, effectively eliminating the tailing. The improved method has a good sizing performance and can resolve the size fractions of mixed 30 nm and 50 nm AuNPs. It can reliably analyze 7.8 × 105 to 1.9 × 107 # of 50 nm AuNPs (or 4.1 × 105 to 107 # NPs/mL, equivalent to 0.6 to 14.3 μg Au/L) with a linear response and a limit of detection of 7.8 × 105 # AuNPs (equivalent to 4.1 × 105 # AuNPs/mL) that is relevant to NP concentrations in surface water and wastewater samples. The potential of this method to analyze environmental samples was demonstrated by characterizing AuNPs and silver nanoparticles (AgNPs) spiked in wastewater, where both NPs were revealed to form heteroaggregates with colloids existing in wastewater. The method can even directly analyze nanosized Ag particles inherent in the wastewater before adding external AgNPs. The result indicates that ATM-DMA-spICP-MS is a relatively simple two-dimensional size analysis method that has a great potential to characterize heteroaggregated NPs in aqueous environmental samples.

Risk Assessment of Personal Care Products, Pharmaceuticals, and Stimulants in Mgeni and Msunduzi Rivers, KwaZulu-Natal, South Africa

In this work, environmental occurrence and risk assessment of pharmaceuticals, personal care products (PPCPs), and stimulants are presented. A quantitative technique is described for ultrasonic-assisted solid-phase extraction (SPE) followed by GC-MS after derivatization of PPCPs; propylparaben, triclosan, carbamazepine, chloramphenicol, and stimulant caffeine. Ultrasonic-assisted extraction together with centrifugation were used to extract sediment samples collected from the Mgeni and Msunduzi rivers. An SPE procedure was used for cleanup and to concentrate selected compounds from diluted aqueous extracts. The final extracts were derivatized and analyzed with GC-MS in selected ion monitoring (SIM) mode. The recoveries of the analytes ranged from 66 to 108%. The method detection limits were (0.08–1.82 ng g−1 for solid and 0.08–10 μg L−1 for liquid) and quantification limits (0.42–5.51 ng g−1 for solid and 0.25–25 μg L−1 for liquid). The optimized method was applied in the evaluation of two rivers over 3 months in KwaZulu-Natal, South Africa. All targeted compounds were present in the environment at concentration levels between not detected to 174 ng g−1 and not detected to 30 μg L−1 for solids and aqueous environmental samples, respectively. A comparison of predicted no environmental effect concentration (PNECs) with measured environmental concentration (MECs) showed that these PPCPs present a high ecological risk to the receiving environment (agricultural lands and households). Our work is close to reality because we used MECs as opposed to using predicted environmental concentration (PECs) values, which are normally calculated from consumption, production of compound per year, and various estimated factors.

Establishment and application of a TaqMan probe-based qPCR for the detection of Enterocytozoon hepatopenaei in shrimp Litopenaeus vannamei.

Enterocytozoon hepatopenaei (EHP) is a common parasite that invades the epithelial cytoplasm in the hepatopancreas of shrimp Litopenaeus vannamei and results in slow growth of the host shrimps to cause significant economic loss in shrimp aquaculture. In this study, a TaqMan probe-based qPCR for quantitative detection of EHP was established. A pair of specific primers and a TaqMan probe were designed based on the sequence of cysteine desulfurase gene (NFS1) of EHP. The standard curve between cycle threshold (Ct) and the logarithmic starting quantity (SQ) of the template was determined as Ct = - 3.231 lg (SQ) + 40.638, with a correlation coefficient (R2) of 0.998 and an amplification efficiency of 103.9%. The lower limit of quantification was 1.67 × 101 copies/μL for this TaqMan probe-based qPCR and 1.67 × 103 copies/μL for the conventional PCR. The TaqMan probe-based qPCR established in the research was 100 times more sensitive than the conventional PCR method. In addition, the results of clinical sample detection indicated that the present technique was efficient in detecting EHP in the hepatopancreas, feces, water, and pond bottom mud samples. Therefore, the established TaqMan probe-based qPCR is a suitable technique for detecting EHP in both shrimp and aquatic environment samples.

Electrochemical detection of the antiprotozoal drug dimetridazole using κ-carrageenan functionalized gadolinium tin oxide nanoparticles

Dimetridazole (DMZ) is an antimicrobial drug used to treat bacterial and protozoan infections in humans and poultry farms. An excessive dosage of DMZ can be life-threatening, as it has carcinogenic effects. Hence, ensuring that DMZ remains at a very low level in the environment is essential for day-to-day human life. Herein, we report the development of a novel biocomposite using κ-carrageenan (κ-CGN) functionalized with gadolinium tin oxide nanoparticles (NPs), κ-CGN/GdSnO2NPs, for the effective electrochemical detection of DMZ. The biocomposites, κ-GCN/GdSnO2NPs, were successfully synthesized by the sonochemical method, and their structural features were evaluated using various spectroscopic and microscopic techniques. A glassy carbon electrode was coated with the synthesized κ-CGN/GdSnO2NPs, it was used as an electrode surface modifier material for the detection of DMZ, and it exhibited excellent electrocatalytic activity. In addition, the modified electrode showed many advantages, such as a lower detection limit (3.1 nM), wide linear range (0.019–708.8 µM), good sensitivity (0.62 µA µM−1 cm−2), and high selectivity in the presence of co-interfering species. The designed κ-CGN/GdSnO2NPs-based composite material can contribute to outstanding sensor performance in aquatic samples because of its repeatability, reproducibility, storage stability, and satisfactory accuracy. Therefore, κ-CGN/GdSnO2NPs could be used to develop potential electrode modifier materials for electrochemical sensor applications and to detect toxic components, such as DMZ, in environmental aquatic samples.

Online water sampling-quickMix-assisted miniscale liquid-liquid extraction coupled with full evaporation dynamic headspace concentration of polybrominated diphenyl ethers

Polybrominated diphenyl ethers (PBDEs) are commonly used as flame retardants in daily household products and have been found to be detrimental to human and animal health. Being highly stable, accumulation can take place easily in the environment. In our previous studies, an innovative sample preparation method named miniscale liquid-liquid extraction (msLLE) coupled to full evaporation dynamic headspace (FEDHS) concentration was developed, and then successfully coupled to an online water sampling system, allowing full automation from water sampling to sample preparation, sample detection and analysis. In the present work, the fully automated online sampling-quickMix-assisted-msLLE-FEDHS platform was optimized and applied to PBDEs in environmental aqueous samples. The online sampling system was set up with a modified sample vial (to have an inlet and outlet), two tubings and a peristaltic pump which was programmed to control the water flow into and out of the vial. After adding 2 mL of the extractant (n-hexane), and 7 mL of sampled water to a 10-mL vial, msLLE was enabled, assisted with a quickMix module to ensure a quick and efficient mode of mixing between the organic and aqueous phases. The organic extract was then transferred to the FEDHS setup for selective trapping and concentration of the PBDEs, while the solvent was removed. The trap consisted of Tenax TA adsorbent, which has favorable π-interaction with the PBDEs but not with n-hexane. Subsequently, the adsorbent tube was automatically transported to the injector of the gas-chromatography mass-spectrometric (GC–MS) system to thermally desorb the trapped PBDEs for detection and analysis. The optimized methodology was found to achieve low limits of detection (0.0031 to 0.018 µg/L) with good linearity (r2 ≥ 0.9932) and satisfactory absolute extraction recoveries (between 61.4% and 80.9%). The analysis of PBDEs in spiked genuine water sample attained satisfactory and repeatable relative recoveries (between 106.1% and 132.6% with%RSDs ≤ 8.6%).

Novel biogenic gold nanoparticles stabilized on poly(styrene-co-maleic anhydride) as an effective material for reduction of nitrophenols and colorimetric detection of Pb(II)

Biogenic gold nanoparticles (AuNPs) have been extensively studied for the catalytic conversion of nitrophenols (NP) into aminophenols and the colorimetric quantification of heavy metal ions in aqueous solutions. However, the high self-agglomeration ability of colloidal nanoparticles is one of the major obstacles hindering their application. In the present study, we offered novel biogenic AuNPs synthesized by a green approach using Cistanche deserticola (CD) extract as a bioreducing agent and stabilized on poly(styrene-co-maleic anhydride) (PSMA). The prepared Au@PSMA nanoparticles were characterized by various techniques (HR-TEM, SEAD, FE-SEM, DLS, TGA, XRD, and FTIR) and studied for two applications: the catalytic reduction of 3-NP by NaBH4 and the sensing detection of Pb2+ ions. The optimal conditions for the synthesis of AuNPs were investigated and established at 60 °C, 20 min, pH of 9, and 0.5 mM Au3+. Morphological studies showed that AuNPs synthesized by CD extract were mostly spherical with a mean diameter of 25 nm, while the size of polymer-integrated AuNPs was more than two-fold larger. Since PSMA acted as a matrix keeping the nanoparticles from coagulation and maintaining the optimal surface area, AuNPs integrated with PSMA showed higher catalytic efficiency with a faster reaction rate and lower activation energy than conventional nanoparticles. Au@PSMA could completely reduce 3-NP within 10 min with a rate constant of 0.127 min−1 and activation energy of 9.96 kJ/mol. The presence of PSMA also improved the stability and recyclability of AuNPs. Used as a sensor, Au@PSMA exhibited excellent sensitivity and selectivity for Pb2+ ions with a limit of detection of 0.03 μM in the linear range of 0–100 μM. The study results suggested that Au@PSMA could be used as a promising catalyst for the reduction of NP and the colorimetric sensor for detection of Pb2+ ions in aqueous environmental samples.