Authentic Water Samples Research Articles

Engineering an upconversion fluorescence sensing platform with "off-on" pattern through specific DNAzyme-mediated signal amplification for supersensitive detection of uranyl ion.

Anupconversion fluorescence sensing platform was developedwith upconversion nanoparticles (UCNPs) as energy donors and gold nanoparticles (AuNPs) as energy acceptors, based on the FRET principle. They were used for quantitativedetection ofuranyl ions (UO22+) by amplifying the signal of the hybrid chain reaction (HCR). When UO22+ are introduced, the FRET between AuNPs and UCNPs can be modulated through a HCR in the presence of high concentrations of sodium chloride. This platform providesexceptional sensitivity, with a detection limit as low as 68pM for UO22+ recognition. We have successfully validated the reliability of this method by analyzing authentic water samples, achieving satisfactory recoveries (89.00%-112.50%) that are comparable to those of ICP-MS. These results indicate that the developed sensing platform has the capability to identify trace UO22+ in complex environmentalsamples.

Near-infrared and multifunctional fluorescent probe enabled by cyanopyridine cyanine dye for bisulfite recognition and biological imaging

SO2 derivatives, sulfite/bisulfite, are widely employed in both the food processing and drug synthesis industries. Despite their widespread application, excessive levels of sulfite/bisulfite can negatively impact human health. Most probes for detecting sulfite/bisulfite are restricted by their fluorescence within the visible spectrum range and poor solubility in aqueous solution, which limit their use in food testing and biological imaging. Herein, a near-infrared probe comprising of the cyanopyridine cyanine skeleton, 4-((Z)−2-((E)−2-chloro-3-(2-cyano-2-(1-methylpyridine-4(1H)-ylidene)ethylidene)cyclohex-1-en-1-yl)−1-cyanovinyl)−1-methylpyridin-1-ium (abbreviated as CCP), was developed. This probe enables precise quantification of bisulfite (HSO3-) in almost pure buffered solutions, showing a near-infrared fluorescence emission at 784 nm with an impressively low detection limit of 0.32 μM. The probe stands out for its exceptional selectivity, minimal susceptibility to interference, and strong adaptability. The probe CCP utilizes the CC bond to trigger a near-infrared fluorescence quenching reaction with HSO3- via nucleophilic addition, which effectively disrupts the large delocalization within the molecule for accurate HSO3- identification. Moreover, the probe has been successfully applied in detecting HSO3- in various food products and living cells, simplifying the measurement of HSO3- content in water samples. This advancement not only enhances the analytical capabilities but also contributes to ensuring food safety and environmental protection. Environmental ImplicationSO2 derivatives including sulfite/bisulfite, serving dual roles as preservatives and antioxidants, have widespread application across various sectors including food preservation, water sanitation, and the pharmaceutical industry. Despite their widespread application, excessive levels of sulfite/bisulfite can affect human health. Developing methods for precisely and sensitively detecting sulfite/bisulfite in food products and biological samples is important for ensuring food safety and environmental protection. Here, a sensitive near-infrared and multifunctional fluorescent probe in a 99.9 % buffered solution, along with water gel encapsulation, has been successfully applied for the detection of bisulfite in food, authentic water samples, and biological cells.

Transformative strategies for heavy metals extraction: Ionic liquid-boosted fizzy capsule for distributive solid-phase microextraction in aquatic environments

Within this work, an innovative ionic liquid-coated sulphonyl silanized graphene oxide-supported fizzy capsule-enhanced ionic liquid distributive solid-phase micro-extraction (MGO@SO3H-IL-DSPM) was successfully prepared for enriching and extracting lead [Pb(II)], cadmium [Cd(II)], and cobalt [Co(II)] ions from water samples. The MGO@SO3H hybrid was investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Zeta potential and surface area. Exploration and optimization were conducted on various parameters including solution pH, dosages of extractant, volume of ionic liquid, and the type and concentration of eluent. The optimized experimental conditions for achieving high extraction efficiencies of the targeted metals were determined as follows: a mixture of Na2CO3 and NaH2PO4 (0.12 g) each, at a 1:1 M ratio); utilization of 0.03 g of MGO@SO3H nanocomposites; addition of 10 μL of ionic liquid as the extractant; pH adjustment to approximately 5 for Pb(II), and 4.18 for both Co(II) and Cd(II); and elution using HNO3 as the eluent (at a concentration of 1.5 M, with a volume of 3 ml). Under the ideal circumstances, the extraction yield efficiencies of the target metal ions in four authentic water samples were in the range (96.09 % − 100 %) for Cd(II), (99.99 % − 102 %) for Pb(II), and (99.99 % − 103 %) for Co(II), the RSDs were lower than 1.7 %. The content of Cd(II), Pb(II), and Co(II) ions in four actual samples of water were determined within the range of 1.25 – 3.75 μg/L, 6 – 15 μg/L, and 29.15 – 70 μg/L, respectively.

Predicting Odor Sensory Attributes of Unidentified Chemicals in Water Using Fragmentation Mass Spectra with Machine Learning Models.

Knowing odor sensory attributes of odorants lies at the core of odor tracking when addressing waterborne odor issues. However, experimental determination covering tens of thousands of odorants in authentic water is not pragmatic due to the complexity of odorant identification and odor evaluation. In this study, we propose the first machine learning (ML) model to predict odor perception/threshold aiming at odorants in water, which can use either molecular structure or MS2 spectra as input features. We demonstrate that model performance using MS2 spectra is nearly as good as that using unequivocal structures, both with outstanding accuracy. We particularly show the model's robustness in predicting odor sensory attributes of unidentified chemicals by using the experimentally obtained MS2 spectra from nontarget analysis on authentic water samples. Interpreting the developed models, we identify the intricate interaction of functional groups as the predominant influence factor on odor sensory attributes. We also highlight the important roles of carbon chain length, molecular weight, etc., in the inherent olfactory mechanisms. These findings streamline the odor sensory attribute prediction and are crucial advancements toward credible tracking and efficient control of off-odors in water.

Determination of NTA and EDTA in authentic water samples by LC-MS/MS combined with precolumn methylation

Nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA), as widely used chelating agents, have created many environmental issues and raised much attention regarding their environmental occurrence. However, the determination of NTA and EDTA in samples of complex solution chemistry remains challenging. Here, we proposed a simple and sensitive method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine NTA and EDTA from aqueous samples without an enrichment step. During the analysis, H+-cation exchange was used to efficiently eliminate interference from metal ions. The intensity of NTA and EDTA with trimethylsilyldiazomethane methylation could be improved hundreds of times that of the virgin samples. To maximize sensitivity, the sample pretreatment methods, the derivatization procedures and the LC-MS/MS conditions were systematically optimized. The validated method showed low limits of quantification (0.4 μg/L for NTA and 1.5 μg/L for EDTA), a wide linear response (up to several mg/L, R2 > 0.998), and good intra- and inter-day precision (relative standard deviation ≤ 11%). The reliability of this method was successfully validated by analysis of authentic water samples collected from three WWTPs and one river with satisfactory recoveries (80–117%). It can be proposed as a powerful analytical method of NTA and EDTA in authentic water samples and could potentially be adapted to detect other chelates and polydentate compounds.

Electrochemical sensor based on onion-like carbon (OLC) materials modified electrode for sensitive determination of 4-nitrophenol

Due to its advantageous features, the electrochemical technique has garnered considerable attention in detecting 4-nitrophenol (4-NP). And the modified materials of such working electrode significantly influence the sensitivity of the electrochemical sensor. In this investigation, a sensitive and selective electrochemical sensor for detecting 4-NP in real water samples was developed by using a spherical onion-like carbon (OLC) as a new material for electrode modification. By comparing with generally used carbon nanotube (CNT), OLC exhibits higher electroactive surface area and conductibility. The electroactive surface area of OLC modified glassy carbon electrode (OLC/GCE) and CNT modified GCE (CNT/GCE) was determined to be 0.1508 cm2 and 0.1231 cm2 respectively. Notably, the OLC/GCE (Ipc:−139 μA) exhibited a significantly higher reduction peak current for 4-NP reduction in contrast to CNT/GCE (Ipc:−94 μA) determined by the cyclic voltammetry test. Remarkably, under ideal conditions, the OLC/GCE displayed a linear detection range for 4-NP spanning from 0.05 to 120 μM, with an exceptionally low identifying limit of 3.74 nM. In addition, OLC/GCE exhibits excellent selectivity, reproducibility, and repeatability for determining 4-NP. And the current response remains about 92% of its primal value 15 days later, demonstrating an outstanding stability of OLC/GCE. Furthermore, OLC/GCE was successfully employed in determining 4-NP in authentic water samples, yielding satisfactory recovery rates ranging from 96.14% to 102.1%. This investigation exemplifies the outstanding sensing capabilities and promising potential of OLC in the field of electrochemically detecting 4-NP in environmental settings, which provides a new method for the simple, sensitive and quantitative detection of 4-NP.

HDPairFinder: A data processing platform for hydrogen/deuterium isotopic labeling-based nontargeted analysis of trace-level amino-containing chemicals in environmental water

The combination of hydrogen/deuterium (H/D) formaldehyde-based isotopic methyl labeling with solid-phase extraction and high-performance liquid chromatography–high resolution mass spectrometry (HPLC-HRMS) is a powerful analytical solution for nontargeted analysis of trace-level amino-containing chemicals in water samples. Given the huge amount of chemical information generated in HPLC-HRMS analysis, identifying all possible H/D-labeled amino chemicals presents a significant challenge in data processing. To address this, we designed a streamlined data processing pipeline that can automatically extract H/D-labeled amino chemicals from the raw HPLC-HRMS data with high accuracy and efficiency. First, we developed a cross-correlation algorithm to correct the retention time shift resulting from deuterium isotopic effects, which enables reliable pairing of H- and D-labeled peaks. Second, we implemented several bioinformatic solutions to remove false chemical features generated by in-source fragmentation, salt adduction, and natural 13C isotopes. Third, we used a data mining strategy to construct the AMINES library that consists of over 38,000 structure-disjointed primary and secondary amines to facilitate putative compound annotation. Finally, we integrated these modules into a freely available R program, HDPairFinder.R. The rationale of each module was justified and its performance tested using experimental H/D-labeled chemical standards and authentic water samples. We further demonstrated the application of HDPairFinder to effectively extract N-containing contaminants, thus enabling the monitoring of changes of primary and secondary N-compounds in authentic water samples. HDPairFinder is a reliable bioinformatic tool for rapid processing of H/D isotopic methyl labeling-based nontargeted analysis of water samples, and will facilitate a better understanding of N-containing chemical compounds in water.

Rapid microwave fabrication of red-carbon quantum dots as fluorescent on-off-on probes for the sequential determination of Fe(III) ion and ascorbic acid in authentic samples.

In this study, fluorescent red-carbon quantum dots (R-CQDs) with an ultrahigh fluorescence quantum yield of 45% were rapidly and easily synthesized by thermal pyrolysis of 2,5-diaminotoluene sulfate and 4-hydroxyethylpiperazineethanesulfonic acid using a one-step microwave-assisted hydrothermal approach. R-CQDs possessed the excitation-independent fluorescence property with the optimal emission peak at 607 nm under the excitation wavelength of 585 nm. R-CQDs exhibited excellent fluorescence stability under extremely harsh conditions in a pH range of 2-11, high ionic strength (1.8 M of NaCl), and long UV light irradiation time (160 min). The fluorescence quantum yield of these R-CQDs was as high as 45%, implying their preferable application in chemosensors and biological analysis. Because Fe3+ ion bound with R-CQDs and statically quenched the fluorescence of R-CQDs, the fluorescence intensity of R-CQDs was recovered after the addition of ascorbic acid (AA) via its redox reaction with Fe3+ ion. R-CQDs were developed as highly sensitive fluorescent on-off-on probes for sequentially sensing Fe3+ ions and AA. Under the optimal experimental conditions, the linear range for Fe3+ ion detection was 1-70 μM with a detection limit of 0.28 μM, and the linear range for AA detection was 1-50 μM with a detection limit of 0.42 μM. The successful detection of Fe3+ ions in authentic water samples and the successful sensing of AA in human body fluids and vitamin C tablets further proved the practical application prospects of this efficient strategy in the environmental protection and disease diagnosis fields.

Comprehensive GC×GC-qMS with a mass-to-charge ratio difference extraction method to identify new brominated byproducts during ozonation and their toxicity assessment

Ozonation might increase the risk of wastewater due to byproduct formation, especially in the presence of bromide. In this study, a new analytical method was developed to identify new brominated disinfection byproducts (Br-DBPs) during ozonation, using comprehensive two-dimensional gas chromatography-single quadrupole mass spectrometry (GC×GC-qMS) connected with an electron capture detector in parallel. The obtained data were analyzed using a mass-to-charge ratio (m/z) difference extraction method. Over 1304 DBPs were detected in an ozonated phenylalanine solution. Further screening of 635 DBPs was conducted using the m/z difference extraction method. Finally, the structures for 12 Br-DBPs were confirmed and for 4 Br-DBPs were tentatively proposed by comparison with the NIST library and standard compounds. Eight of the confirmed Br-DBPs are first reported and identified: 2-bromostyrene, 1-bromo-1-phenylethylene, 2-bromobenzaldehyde, 3-bromobenzaldehyde, 4-bromobenzaldehyde, 2-bromophenylacetonitrile, 3-bromophenylacetonitrile and 4-bromophenylacetonitrile. These DBPs and 2,4,6-tribromophenol were detected at nanogram- to microgram-per-liter concentrations during ozonation of authentic water samples like algal bloom waters, wastewater treatment plant effluents, and surface water. The toxicities of these compounds were generally higher than that of bromate. The developed analytical method is a powerful technique for analyzing complex compounds and provides a novel way of identifying byproducts in future studies.

A preliminary exploration on Au nanoparticles-mediated colorimetric analysis of Cr(III)-carboxyl complexes in synthetic and authentic water samples

Toxic metal-organic complexes are ubiquitous in contaminated waters but more challenging than free ion counterparts for water decontamination. Currently, almost all the available analytical methods, including Au nanoparticles-mediated colorimetric assay, cannot discriminate metal-organic complexes from the total metal content, which greatly impedes the development of specific decontamination strategies for metal-organic complexes. In this study, we found that nitrilotriacetic acid (NTA) functionalized AuNPs could be used to determine various Cr(III) complexes (Cr(III)-lactate, Cr(III)-malonate, Cr(III)-oxalate, Cr(III)-tartrate, Cr(III)-citrate and Cr(III)-EDTA) in water. Mechanism study indicated that at acidic pHs (pH = 1.6), the protonation of organic ligands resulted in partial dissociation of Cr(III) from the corresponding complexes to expose its accessible orbitals for re-coordination with NTA. Such re-coordination induces the aggregation of the dispersed NTA-AuNPs and thereafter causes considerable changes both in color and UV–Vis spectrum of the solution. The nanosensor is highly selective to Cr(III)-organic complexes with detection limits of 0.029 μM for Cr(III)-lactate, 0.043 μM for Cr(III)-malonate, 0.35 μM for Cr(III)-oxalate, 0.079 μM for Cr(III)-tartrate, 2.58 μM for Cr(III)-citrate and 0.90 μM for Cr(III)-EDTA, respectively. The feasibility of the proposed colorimetric assay has been verified by using the authentic natural and industrial water samples. We believe this study will be of fundamental significance to push forward the application of Au NPs colorimetric assay in authentic waters contaminated by toxic metals.

Analysis of trace phosphonates in authentic water samples by pre-methylation and LC-Orbitrap MS/MS

Phosphonate is an important phosphorous species in the effluent of wastewater treatment plant (WWTP), contributing to eutrophication and interfering with phosphate removal in WWTP. It is particularly difficult to determine phosphonates in samples of complex solution chemistry, resulting in very limited information on their presence in environmental matrices. Herein, we proposed a sensitive method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine six quantitatively most important phosphonates even at the ng/L level, i.e., 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethane 1,1-diphosphonic acid, nitrilotris(methylene phosphonic acid), ethylenediamine tetra(methylene phosphonic acid), hexamethylenediamine tetra(methylene phosphonic acid) and diethylenetriamine penta(methylene phosphonic acid). Trimethylsilyldiazomethane (TMSCHN2) derivatization of the target phosphonates is pre-requisite since it could greatly increase the sensitivity up to 2-3 orders of magnitude over direct analysis of the virgin ones. The sample pretreatment methods (including ion exchange and solid phase extraction(SPE)), the derivatization procedures, and the LC-MS/MS conditions were systematically optimized. The limits of quantitation for the six phosphonates in the background of tap water ranged from 1.4 μg/L to 57 μg/L for direct analysis, and from 5.0 ng/L to 200 ng/L for SPE enabled pre-concentration analysis, respectively. The reliability of the proposed method was successfully validated by analysis of authentic water samples collected from one river and three WWTPs (0.088–7200 μg/L phosphonates) with satisfactory recoveries (72–126%). To the best of knowledge, this is the first report on quantification of phosphonates in environmental samples in China.

Formation, Identification, and Occurrence of New Bromo- and Mixed Halo-Tyrosyl Dipeptides in Chloraminated Water.

Dipeptides are widely present in surface water and serve as precursors to form disinfection byproducts (DBPs) during disinfection (e.g., chloramination). Bromide (Br-) and iodide (I-) are common in many source waters, enhancing Br- and I-DBP formation. Recently Cl-, I-, and Cl-I-dipeptides were identified after chloramination of tyrosyl dipeptides in the presence of I- and were detected in authentic disinfected drinking water samples. However, the formation and occurrence of Br- and mixed halogen (Cl, Br, and/or I)-dipeptides in disinfected water have not been studied. Here we investigated the formation of halogenated dipeptides from three aromatic dipeptides, phenylalanylglycine (Phe-Gly), tyrosylalanine (Tyr-Ala), and tyrosylglycine (Tyr-Gly), under chloramination in the presence of Br- and I- at environmentally relevant levels ([Br-] and [I-], 0 and 0 μg L-1, 6 and 30 μg L-1, 30 and 30 μg L-1, 150 and 30 μg L-1, 300 and 30 μg L-1, and 900 and 30 μg L-1, respectively). For the first time, N-Br- and N,N-di-Br- as well as N-Br- N-Cl- and N-Br-3-I-tyrosyl dipeptides were identified using infusion electrospray quadrupole time-of-flight mass spectrometry. Tyrosyl dipeptides produced N-Cl-, 3-I-/3,5-di-I-, and N-Cl-3-I-tyrosyl dipeptides, while Phe-Gly formed only N-Cl-/ N, N-di-Cl-Phe-Gly. To determine halogenated dipeptides in authentic water samples, we developed a new method of solid phase extraction and high-performance liquid chromatography with quadrupole ion trap mass spectrometry using reaction monitoring. 3,5-Di-I-Tyr-Ala and N-Br-Tyr-Ala were detected in treated water but not in the corresponding raw water, warranting further investigation into the occurrence of halogenated peptides in other drinking water systems.

Determination of Polycyclic Aromatic Hydrocarbons in Water by Solid-Phase Microextraction and Liquid Chromatography

This study describes the determination of polycyclic aromatic hydrocarbons (PAHs) in water using high-performance liquid chromatography (HPLC) coupled with fluorescence detection (FLD). Because individual PAHs are generally present in water only at trace levels, a sensitive and accurate determination technique is essential. The separation and detection of five PAHs were run completely within 25 min by the HPLC/FLD system with an analytical C18 column, a fluorescence detection, and acetonitrile-water gradient elution. Calibration graphs were linear with very good correlation coefficients (r > 0.9998), and the detection limits were in the range of 2-6 ng/l for five PAHs. Solid phase microextraction (SPME) was performed for sample pretreatment prior to HPLC-FLD determination, and the governing parameters were investigated. Compared to conventional methods, SPME has high recovery, saves considerable time, and reduces solvents waste. The extraction efficiencies of five PAHs were above 88% and the extraction times were 35 min in one pretreatment procedure. One particular discovery is that 1.5 M sodium monochloroactate (ClCH2COONa) can improve the extraction yield of PAH compounds more than other inorganic salts. The SPME-HPLC-FLD technique provides a relatively simple, convenient, practical procedure, which was here successfully applied to determine five PAHs in water from authentic water samples.

Fast chromatographic separation techniques as competitors to chemical and biochemical sensor systems

Fast chromatographic methods, e.g. chromatography with supercritical fluids, ion chromatography and especially capillary electrophoresis, are important competitors of chemical sensors in environmental monitoring and process control. These methods show high selectivity and low interferences and it is possible to determine several parameters within a single chromatographic run. In order to show the potential and limitation of sensor systems and chromatographic separation methods in environmental analysis this review is limited to applications in this field. With regard to practical problems a comparison of ion chromatography (IC), capillary electrophoresis (CE) and electrochemical sensors is given for a special example, the ion analysis in waste water. Authentic water samples with a high surfactant content from a car-wash are examined, proving the suitability of IC, CE and electrochemical sensors in terms of specifity, sensitivity, reproducibility, analysis time and calibration linearity. The results show that the chromatographic methods are useful techniques in water analysis, yielding good sensitivity, high resolution and short analysis times. In comparison the chemical sensor also shows short analysis times, good sensitivity and a simple instrumental set-up. The disadvantage is the lack of selectivity and the instability of the sensor signal, when the sensor is exposed to the extremely complex matrix. Good results could only be achieved by pretreatment of the sample solution.