Development, validation, and implementation of an ultratrace analysis method for the determination of moenomycin A, in aquatic animal products.

Moenomycin A, an antimicrobial growth promoter widely used as an additive in aquaculture feedstuffs, has been restricted for use in the European Union and China due to its potential risk of promoting resistant strains of pathogenic bacteria and causing residues in aquatic animal products. Although methods for analyzing moenomycin A in feedstuffs have been developed, no established method exists for aquatic matrices. In this study, we present, for the first time, a sensitive and validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of moenomycin A in aquatic animal products. Samples were extracted using methanol and purified with the QuEChERS method employing C18 sorbent. The aliquot was dried under a nitrogen stream, reconstituted with methanol-water solvent, and analyzed by HPLC-MS/MS. The developed method exhibited good linearity (r2 > 0.995) over a wide concentration range (1-100 µg/L) and a low limit of detection (1 µg/kg). Average recoveries ranged between 70 and 110% at spiked concentrations of 1, 50, and 100 µg/kg, with associated intra- and inter-day relative standard deviations of 1.25 to 7.32% (n = 6) and 2.91 to 10.08% (n = 3), for different representative aquatic animal production, respectively. To the best of our knowledge, this is the first reported HPLC-MS/MS method for the quantification of moenomycin A in aquatic animal products. The new approach was effectively employed in the analysis of moenomycin A across various aquatic samples.

Pharmacokinetics studies of eugenol in Pacific white shrimp (Litopenaeus vannamei) after immersion bath.

BACKGROUND: Eugenol is the most commonly used plant anesthetic to relieve the stressors during various aquaculture procedures. This study aims to investigate the pharmacokinetics of eugenol in Pacific white shrimp by immersion baths in a simulated transportation. RESULTS: The pharmacokinetics of eugenol were firstly investigated in Pacific white shrimp by immersion baths of 300 mg L- 1 eugenol over 5 min (Treatment 1), 10 mg L- 1 eugenol during 24 h (Treatment 2) and a sequential immersion administration (Treatment 3). Concentrations of eugenol in hemolymph, hepatopancreas, and muscle were determined using Gas chromatography-tandem mass spectrometry (GC-MS/MS). After immersion bath of Treatment 1, the elimination half-life (t1/2z) values are 1.3 h and 11 h for hepatopancreas and muscles, indicating the rapid absorption and elimination of eugenol in shrimp. Under the Treatment 2 administration, the eugenol peak concentration is 6527.9 µg/kg in muscle, followed by 402.8 µg/kg in hepatopancreas, with the lowest concentration of 37.9 µg/L in hemolymph. Area under the curve (AUC0-∞) values lie in the order of muscle > hepatopancreas > hemolymph, suggesting that eugenol tends to accumulate in muscle by the immersion administration. Moreover, the average residence time (MRT0-∞) values of 38.6, 23.0 and 115.3 h for hemolymph, hepatopancreas and muscle are achieved, which may indicate that hepatopancreas is the main organ for elimination of eugenol. After combining the conditions in a sequential bath immersion of eugenol (Treatment 3), the maximum concentration (Cmax) values of eugenol are higher than those achieved in Treatment 2, indicating that accumulation of eugenol happened in haemolymph, hepatopancreas and muscle. In addition, the corresponding t1/2z values are 4.7, 14.9 and 47.6 h, respectively, suggesting the faster elimination from the tissues following sequential administration. After the immersion bath, eugenol concentrations in muscle of Pacific white shrimp are lower than 2.5 mg/kg at 2 h, 48 h and 24.5 h in Treatment 1 ~ 3. CONCLUSIONS: A withdrawal period of 2 h, 48 h and 24.5 h following a 300 mg L- 1 of eugenol over a 5-min, 10 mg L- 1 eugenol concentration during a 24-h and combined conditions in a sequential immersion bath were suggested.

Determination of Methylene Blue and Its Metabolite Residues in Aquatic Products by High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

A sensitive and reliable method was developed to determine methylene blue (MB) and its metabolite residues, including azure A (AZA), azure B (AZB), and azure C (AZC) in aquatic products by HPLC-MS/MS. The samples were extracted by acetonitrile and cleaned up by alumina-neutral (ALN) cartridges. The analytes were separated on a Sunfire C18 column (150 mm × 2.1 mm, 5 µm). The method was validated according to the European criteria of Commission Decision 2002/657/CE. Good linearity between 1-500 µg/L was obtained with correlation coefficients (R2) greater than 0.99. The limit of quantification (LOQ) was 1.0 µg/kg. The average recoveries at three levels of each compound (1, 5, and 10 µg/kg) were demonstrated to be in the range of 71.8-97.5%, with relative standard deviations (RSDs) from 1.05% to 8.63%. This method was suitable for the detection of methylene blue and its metabolite residues in aquatic products.

Label-free counting of affinity-enriched circulating tumor cells (CTCs) using a thermoplastic micro-Coulter counter (µCC).

Coulter counters are used for counting particles and biological cells. Most Coulter counters are designed to analyze a sample without the ability to pre-process the sample prior to counting. For the analysis of rare cells, such as circulating tumor cells (CTCs), it is not uncommon to require enrichment before counting due to the modest throughput of µCCs and the high abundance of interfering cells, such as blood cells. We report a microfluidic-based Coulter Counter (µCC) fabricated using simple, low-cost techniques for counting rare cells that can be interfaced to sample pre- and/or post-processing units. In the current work, a microfluidic device for the affinity-based enrichment of CTCs from whole blood into a relatively small volume of ∼10 µL was interfaced to the µCC to allow for exhaustive counting of single CTCs following release of the CTCs from the enrichment chip. When integrated to the CTC affinity enrichment chip, the µCC could count the CTCs without loss and the cells could be collected for downstream molecular profiling or culturing if required. The µCC sensor counting efficiency was >93% and inter-chip variability was ∼1%.

A Lanthanide-Containing Coordination Polymer Using Tetraphenylethene-Based Linkers with Selective Fe3+ Sensing and Efficient Iodine Adsorption Activities.

As a star ligand, the construction of coordination polymers (CPs) based on tetrakis(4-carboxyphenyl)ethylene (H4TCPE) has drawn much attention, due to not only the various coordination configurations but also the intriguing chromophore feature causing aggregation-induced emission (AIE). Herein, by the solvothermal reaction of H4TCPE as connected nodes with lanthanide La(III) salts, the first example of the La(III)-TCPE-based CP (1) has been obtained. The structural analyses indicate that 1 exhibits a 3D framework connected by the sharing carboxylate groups with two kinds of 1D rhombic channels when viewed along the c direction. The photophysical properties of 1 have been explored by luminescence, photoluminescence decay, and quantum yield in the solid state. 1 shows strong luminescence in tetrahydrofuran that was attributed to a "pseudo-AIE process" and sensitive and selective sensing activity of Fe3+ toward metal ions via the obvious luminescent quenching. The sensing mechanism has been investigated and reveals a synergetic effect of the competitive absorption and weak interactions between 1 and Fe3+. Moreover, the high porosity, multiple conjugated π-electrons within the tetrakis(4-carboxyphenyl)ethylene backbone, and the uncoordinated carboxyl oxygen sites in this material also provide the capacity for iodine adsorption. The adsorption experiments indicate that 1 could efficiently remove almost complete I2 from the cyclohexane solution after 24 h contact time with an adsorption capacity of 690 mg/g toward I2.

Simultaneous determination of ten aminoglycoside antibiotics in aquatic feeds by high-performance liquid chromatography quadrupole-orbitrap mass spectrometry with pass-through cleanup.

A simple and sensitive method has been established based on pass-through cleanup and high-performance liquid chromatography quadrupole-orbitrap mass spectrometry (HPLC-Q/Orbitrap MS) for the simultaneous determination of ten aminoglycosides (AGs) in aquatic feeds. The extraction solution and cleanup procedure had been optimized, and good sensitivity, accuracy, and precision were obtained. The calibration curves of AGs were linearity (R2 > 0.99) in the range of 2.0 to 200 µg/L (or 5.0 to 500 µg/L). The limits of detection of AGs were between 10 and 25 µg/kg. The recoveries of AGs ranged from 74.9% to 94.3%, and the intraday and interday relative standard deviations were less than 15%. Finally, this method was successfully applied to determine ten AGs in 30 aquatic feed samples. It might be the first time to use pass-through cleanup approach combined with HPLC-Q/Orbitrap MS method for AGs determination in aquatic feed samples.

Mycobacterium tuberculosis PPE60 antigen drives Th1/Th17 responses via Toll-like receptor 2-dependent maturation of dendritic cells.

Targeting of Mycobacterium tuberculosis (MTB) PE/PPE antigens that induce type 1 helper T cell (Th1) and Th17 responses represents a crucial strategy for the development of tuberculosis (TB) vaccines. However, only a few PE/PPE antigens induce these responses. Here, we sought to determine how the cell wall-associated antigen PPE60 (Rv3478) activates dendritic cell (DC) maturation and T-cell differentiation. We observed that PPE60 induces DC maturation by augmenting the protein expression of cluster of differentiation 80 (CD80) and CD86 and major histocompatibility complex (MHC) class I and MHC class II on the cell surface. PPE60 also stimulated the production of tumor necrosis factor-α (TNFα), interleukin (IL)-1ß, IL-6, IL-12p70, and IL-23p19 but not IL-10. This induction was mediated by Toll-like receptor 2 (TLR2) and followed by activation of p38, c-Jun N-terminal kinase (JNK), and NF-κB signaling. PPE60 enhanced MHC-II expression and promoted antigen processing by DCs in a TLR2-dependent manner. Moreover, PPE60-stimulated DCs directed naïve CD4+ T cells to produce IFN-γ, IL-2, and IL-17A, expanding the Th1 and Th17 responses, along with activation of T-bet and RAR-related orphan receptor C (RORγt) but not GATA-3. Moreover, PPE60 activated the NLRP3 inflammasome followed by caspase-1-dependent IL-1ß and IL-18 synthesis in DCs. Of note, pharmacological inhibition of NLRP3 activation specifically attenuated IFN-γ and IL-17A secretion into the supernatant from CD4+ T cells cocultured with PPE60-activated DCs. These findings indicate that PPE60 induces Th1 and Th17 immune responses by activating DCs in a TLR2-dependent manner, suggesting PPE60's potential for use in MTB vaccine development.

Screening 89 Pesticides in Fishery Drugs by Ultrahigh Performance Liquid Chromatography Tandem Quadrupole-Orbitrap Mass Spectrometer.

Multiclass screening of drugs with high resolution mass spectrometry is of great interest due to its high time-efficiency and excellent accuracy. A high-scale, fast screening method for pesticides in fishery drugs was established based on ultrahigh performance liquid chromatography tandem quadrupole-Orbitrap high-resolution mass spectrometer. The target compounds - were diluted in methanol and extracted by ultrasonic treatment, and the extracts were diluted with MeOH-water (1:1, v/v) and centrifuged to remove impurities. The chromatographic separation was performed on an Accucore aQ-MS column (100 mm × 2.1 mm, 2.6 µm) with gradient elution using 0.1% formic acid in water (containing 5 mmol/L ammonium formate) and 0.1% formic acid in methanol (containing 5 mmol/L ammonium formate) in Full Scan/dd-MS2 (TopN) scan mode. A screening database, including mass spectrometric and chromatographic information, was established for identification of compounds. The screening detection limits of methods ranged between 1-500 mg/kg, the recoveries of real samples spiked with the concentration of 10 mg/kg and 100 mg/kg standard mixture ranged from 70% to 110% for more than sixty compounds, and the relative standard deviations (RSDs) were less than 20%. The application of this method showed that target pesticides were screened out in 10 samples out of 21 practical samples, in which the banned pesticide chlorpyrifos were detected in 3 out of the 10 samples.

Multiclass screening of >200 pharmaceutical and other residues in aquatic foods by ultrahigh-performance liquid chromatography-quadrupole-Orbitrap mass spectrometry.

A quick screening method of more than 200 pharmaceutical and other residues in aquatic foods based on ultrahigh-performance liquid chromatography-quadrupole-Orbitrap mass spectrometry (UHPLC-Q/Orbitrap MS) was established. In this method, after the addition of 200 µL of 1 M EDTA-Na2, 2 g of each sample homogenate was extracted successively with 10 mL of acetonitrile and 10 mL of ethyl acetate. The extracts were combined, dried under nitrogen flow, and redissolved in 0.1% formic acid in acetonitrile/water (4:6, v/v) for analysis. The prepared samples were analyzed by UHPLC- Q/Orbitrap MS system in Full MS/ddMS2 (full-scan data-dependent MS/MS) mode. Compound identification was performed through comparison of the sample data with the database for standard chemicals, including the retention time, precursor ion, product ions, and isotope pattern for all 206 compounds. Five different aquatic food matrices (carp, shrimp, crab, eel, and mussel) spiked with the analytes at 1, 10, and 50 ng/g were evaluated to assess recoveries, precision, matrix effects, stability, and detection limits using the method. UHPLC analyses required 25 min, and 178-200 analytes met identification criteria at 50 ng/g depending on the matrix. Furthermore, practical application of this method for real samples displayed strong screening capability. Graphical abstract A quick screening method of >200 pharmaceutical and other residues in aquatic foods based on ultrahighperformance liquid chromatography-quadrupole-Orbitrap mass spectrometer was established. Fivedifferent aquatic food matrices, including carp, shrimp, crab, eel and mussel, were studied to evaluatescreen limit at 1, 10 and 50 µg·kg-1 level. Results suggest the high reliability, high time-efficiency and goodsimplicity of the method.

Characterization of the Major Purine and Pyrimidine Adducts Formed after Incubations of 1-Chloro-3-buten-2-one with Single-/Double-Stranded DNA and Human Cells.

We have previously shown that 1-chloro-3-buten-2-one (CBO), a potential reactive metabolite of 1,3-butadiene (BD), exhibits potent cytotoxicity and genotoxicity that have been attributed in part to its reactivity toward DNA. In an effort to identify the DNA adducts of CBO, we characterized the CBO reactions with 2'-deoxyguanosine (dG), 2'-deoxycytidine (dC), and 2'-deoxyadenosine (dA) under in vitro physiological conditions (pH 7.4, 37 °C). In the present study, we investigated the CBO reaction with 2'-deoxythymidine (dT) and compared the rate constants of the reactions of CBO with dA, dC, dG, and dT at both individual- and mixed-nucleosides levels. We also investigated the reactions of CBO with single- and double-stranded DNA using HPLC with UV detection after adducts were released by either acid or enzymatic hydrolysis of DNA. Consistent with the results from the nucleoside reactions and the rate constant experiments, 1,N6-(1-hydroxy-1-chloromethylpropan-1,3-diyl)adenine (A-2D) was identified as the major DNA adduct detected after acid hydrolysis, followed by N7-(4-chloro-3-oxobutyl)guanine (CG-2H) and a small amount of 1,N6-(1-hydroxy-1-hydroxymethylpropan-1,3-diyl)adenine (A-1D). After enzymatic hydrolysis, 1,N6-(1-hydroxy-1-hydroxymethylpropan-1,3-diyl)-2'-dexoyadenosine (dA-1), 3,N4-(1-hydroxy-1-hydroxymethylpropan-1,3-diyl)-2'-deoxycytidine (dC-1/2), and 1,N2-(3-hydroxy-3-hydroxymethylpropan-1,3-diyl)-2'-dexoyguanosine (CG-1) were detected, with dA-1 being the major product, followed by dC-1/2. When a nontoxic concentration of CBO (1 µM) was incubated with HepG2 cells, no adducts could be detected by LC-MS. However, pretreatment of cells with l-buthionine sulfoximine to deplete GSH levels allowed A-2D to be consistently detected in cellular DNA. These results may contribute to a better understanding of the role of the DNA adducts in CBO genotoxicity and mutagenicity. It also suggests that A-2D could be developed as a biomarker of CBO formation after BD exposure in vivo.

Loop-mediated isothermal amplification for visual detection of Vibrio parahaemolyticus using gold nanoparticles.

Loop-mediated isothermal amplification (LAMP) eradicates the need of thermocycler in DNA amplification. Signals are usually obtained via fluorometry or turbidimetry, but such methods need improvement in order to become more effortless and reliable. The authors describe a set of six specific primers targeting the species-specific tlh gene of Vibrio parahaemolyticus which were used in accelerated LAMP reaction. Gold nanoparticles (AuNPs) were functionalized with streptavidin (Avidin-AuNPs), and engineered to signal the LAMP reaction. Two of the loop primers for LAMP were biotinylated and then can produce a DNA that can cause clusterization of Avidin-AuNPs based on the formation of avidin-biotin complex. This leads to a color change of the solution from red to blue. Amplification is completed within 30 min and can be visually detected within 5 min. The detection limit of the method is found to be 8.6 cfu per reaction. This visual detection scheme does not require any fluorescent reagents and detection instruments. Conceivably, the method has a wide scope because such Avidin-AuNPs can be used as nanoprobes for a variety of other LAMP products. This rapid and universal strategy holds promise in point of care testing and food testing, particularly in resource-limited regions. Graphical abstract Six specific primers (two of them are biotinylated) were used to realize the accelerated Loop-Mediated Isothermal Amplification. Streptavidin modified gold nanoparticles (Avidin-AuNPs) cluster on the DNA products, leading to the apparent change of color from red to blue, which is readily identified even by unaided eye.

Correction to: Loop-mediated isothermal amplification for visual detection of Vibrio parahaemolyticus using gold nanoparticles.

The published version of this article, unfortunately, contained error. Modifications have been made to the Abstract, Introduction, Results and discussion, and Acknowledgements section. The original article has been corrected.

Identification of a Fused-Ring 2'-Deoxyadenosine Adduct Formed in Human Cells Incubated with 1-Chloro-3-buten-2-one, a Potential Reactive Metabolite of 1,3-Butadiene.

1-Chloro-3-buten-2-one (CBO) is an in vitro metabolite of 1,3-butadiene (BD), a carcinogenic air pollutant. CBO exhibited potent cytotoxicity and genotoxicity that have been attributed in part to its reactivity toward DNA. Previously, we have characterized the CBO adducts with 2'-deoxycytidine and 2'-deoxyguanosine. In the present study, we report on the reaction of CBO with 2'-deoxyadenosine (dA) under in vitro physiological conditions (pH 7.4, 37 °C). We used the synthesized standards and their decomposition and acid-hydrolysis products to characterize the CBO-DNA adducts formed in human cells. The fused-ring dA adducts (dA-1 and dA-2) were readily synthesized and were structurally characterized as 1,N(6)-(1-hydroxy-1-hydroxymethylpropan-1,3-diyl)-2'-deoxyadenosine and 1,N(6)-(1-hydroxy-1-chloromethylpropan-1,3-diyl)-2'-deoxyadenosine, respectively. dA-1 exhibited a half-life of 16.0 ± 0.7 h and decomposed to dA at pH 7.4 and 37 °C. At similar conditions, dA-2 decomposed to dA-1 and dA, and had a half-life of 0.9 ± 0.1 h. These results provide strong evidence for dA-1 being a degradation product of dA-2. dA-1 is formed by replacement of the chlorine atom of dA-2 by a hydroxyl group. The slow decomposition of dA-1 to dA, along with the detection of hydroxymethyl vinyl ketone (HMVK) as another degradation product, suggested equilibrium between dA-1 and a ring-opened carbonyl-containing intermediate that undergoes a retro-Michael reaction to yield dA and HMVK. Acid hydrolysis of dA-1 and dA-2 yielded the corresponding deribosylated products A-1D and A-2D, respectively. In the acid-hydrolyzed reaction mixture of CBO with calf thymus DNA, both A-1D and A-2D could be detected; however, the amount of A-2D was significantly larger than that of A-1D. Interestingly, only A-2D could be detected by LC-MS analysis of acid-hydrolyzed DNA from cells incubated with CBO, suggesting that dA-2 was stable in DNA and thus may play an important role in the genotoxicity and carcinogenicity of BD. In addition, A-2D could be developed as a biomarker of CBO formation in human cells.

Prime-boost bacillus Calmette-Guérin vaccination with lentivirus-vectored and DNA-based vaccines expressing antigens Ag85B and Rv3425 improves protective efficacy against Mycobacterium tuberculosis in mice.

To prevent the global spread of tuberculosis (TB), more effective vaccines and vaccination strategies are urgently needed. As a result of the success of bacillus Calmette-Guérin (BCG) in protecting children against miliary and meningeal TB, the majority of individuals will have been vaccinated with BCG; hence, boosting BCG-primed immunity will probably be a key component of future vaccine strategies. In this study, we compared the ability of DNA-, protein- and lentiviral vector-based vaccines that express the antigens Ag85B and Rv3425 to boost the effects of BCG in the context of immunity and protection against Mycobacterium tuberculosis in C57BL/6 mice. Our results demonstrated that prime-boost BCG vaccination with a lentiviral vector expressing the antigens Ag85B and Rv3425 significantly enhanced immune responses, including T helper type 1 and CD8(+) cytotoxic T lymphocyte responses, compared with DNA- and protein-based vaccines. However, lentivirus-vectored and DNA-based vaccines greatly improved the protective efficacy of BCG against M. tuberculosis, as indicated by a lack of weight loss and significantly reduced bacterial loads and histological damage in the lung. Our study suggests that the use of lentiviral or DNA vaccines containing the antigens Ag85B and Rv3425 to boost BCG is a good choice for the rational design of an efficient vaccination strategy against TB.

Research progress on metabolites of nitrofurazone in aquatic products.

The carcinogenic and teratogenic risks of nitrofurazone (NFZ) led to its restriction in aquatic products. Semicarbazide (SEM), one of its metabolites, is a primary focus of modern monitoring techniques. However, the SEM residue in aquatic products is believed to be formed through endogenous mechanisms, especially for aquatic crustaceans. In this article, we will discuss the source of SEM, including its usage as an antibiotic in aquatic products (nitrofurazone), its production during food processing (azodicarbonamide and hypochlorite treatment), its occurrence naturally in the body, and its intake from the environment. SEM detection techniques were divided into three groups: derivatization, extraction/purification, and analytical methods. Applications based on liquid chromatography and its tandem mass spectrometry, immunoassay, and electrochemical methods were outlined, as were the use of various derivatives and their assisted derivatization, as well as extraction and purification techniques based on liquid-liquid extraction and solid-phase extraction. The difficulties of implementing SEM for nitrofurazone monitoring in aquatic products from crustaceans are also discussed. Possible new markers and methods for detecting them are discussed. Finally, the present research on monitoring illicit nitrofurazone usage through its metabolites is summarised, and potential problems that need to be overcome by continuing research are proposed with an eye toward giving references for future studies.

One step cleanup of 160 pesticides and veterinary drugs in aquatic products using melamine-based automatic pressure filtration purification method combined with HPLC-MS/MS.

A 15-channel pressure filtration purification method was presented for high throughput sample preparation of aquatic products. A cost-effective device was constructed and melamine sponge was selected as the cleanup sorbent. Upon interfacing with HPLC-MS/MS, the analytical procedure demonstrated its suitability for quantifying 160 pesticides and veterinary drug residues in aquatic products such as fish, shrimp, and crab. The method achieved sample recoveries ranging from 61.3 to 124.9 %. The detection limits were established between 0.5 and 1.0 µg/kg, while the quantitation limits were confirmed to be within the range of 1.0-2.0 µg/kg. The method was applied to quantify the pesticide and veterinary drug residues in mostly consumed aquatic products from five coastal provinces in China. The results showed significant differences between different aquatic products in the concentrations of pesticide and veterinary drug residues, implying the necessity of supervision for the accurate determination of pesticides and veterinary drugs.

Development and validation of rapid screening of 192 veterinary drug residues in aquatic products using HPLC-HRMS coupled with QuEChERS.

The presence of veterinary drug residues in aquatic products represents a significant challenge to food safety. The current detection methods, limited in both scope and sensitivity, underscore the urgent need for more advanced techniques. This research introduces a swift and potent screening technique using high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) and a refined QuEChERS protocol, allowing simultaneous qualitative and semi-quantitative analysis of 192 residues. A comprehensive database, employing full scan mode and data-dependent secondary mass spectroscopy, enhances screening accuracy. The method involves efficient extraction using 90% acetonitrile, dehydration with Na2SO4, and acetic acid, followed by cleanup using dispersive solid-phase extract sorbent primary secondary amine. It is suitable for samples with varying fat content, offering detection limits ranging from 0.5 to 10 µg/kg, high recovery rates (60-120%), and low relative standard deviations (<20%). Practical application has validated its effectiveness for multi-residue screening, marking a significant advancement in food safety evaluation.

[Exposure Level and Risk Impact Assessment of Pesticides and Veterinary Drugs in Aquaculture Environment].

To explore the exposure level of pesticides and veterinary drugs in an aquaculture environment and its impact on the ecological environment, this study took the aquaculture environment in Shanghai as an example, and samples of water, sediment, and inputs from 40 major aquaculture farms were collected from July to September 2022. The types and contents of pesticides and veterinary drugs were screened using high-performance liquid chromatography-electrostatic field orbital ion trap mass spectrometry, and the risk quotient (RQ) method was used to assess the ecological risk of pesticide contamination in water and sediment. The results showed that 13 drugs were screened out from 204 samples (72 samples of water, 72 samples of mud, and 60 samples of input), namely, chlorpromazine, carbendazim, thiophanate, diazepam, florfenicol, simazine, amantidine, diazepam, trimethoprim, ciprofloxacin, ofloxacin, mebendazole, and enrofloxacin. Among them, 12 species were found in water samples with concentrations ranging from 0.016 µg·L-1 to 2.084 µg·L-1. The concentrations of seven species in the mud samples ranged from 0.018 µg·kg-1 to 23.101 µg·kg-1. The results showed that there were four types of inputs, ranging from 1.979 µg·kg-1 to 101.940 µg·kg-1. Seven drugs were found in both water and sediment. The risk quotient (RQ) results showed that there were some high and middle risks in both water and sediment samples of aquaculture farms, and the ecological risks of carbendazim were the highest in both water and sediment samples of aquaculture farms; the RQ values were 3.848 and 1.580, respectively, indicating high risk. It is suggested to strengthen the control and management of exogenous pesticides and veterinary drugs in aquaculture environments to protect the ecosystem health of the aquaculture environment.

Tailoring zinc porphyrin to the Ag nanostructure substrate: an effective approach for photoelectrochemical studies in the presence of mononucleotides.

The substituted porphyrin 2-cyano-3-(2'-(5',10',15',20-tetraphenyl porphyrinato zinc-(ii))yl) acrylic acid was used to modify nanostructured Ag surfaces. This porphyrin-modified surface exhibits photocurrent when exposed to a light source, which is modulated in the presence of nucleotides. The addition of the nucleotides adenosine-5'-monophosphate (AMP), guanosine-5'-monophosphate (GMP) and cytidine-5'-monophosphate (CMP) causes partial quenching of the photoelectrochemical response of the porphyrin. The quenching efficiency is 80%, 68% and 48% for AMP, CMP and GMP, respectively. This work represents a new aspect of Ag NS substrates and highlights their usefulness as transducers a for potential chemosensor systems.

Determination of earthy-musty odors in tap water by gas chromatography‒mass spectrometry with silica solid-phase extraction.

This research aimed to develop an effective method for detecting semivolatile earthy-musty odors without using the conventional sample processing equipment used for volatile compounds. The concurrent isolation of 2-methylisoborneol (2-MIB), trans-1,10-dimethyl-trans-9-decalol (geosmin, GSM), 2-isopropyl-3-methoxy pyrazine (IPMP), and 2-isobutyl-3-methoxy pyrazine (IBMP) in tap water was successfully achieved by employing a combination of n-hexane liquid‒liquid extraction (LLE) and silica solid-phase extraction (SPE) techniques. Gas chromatography-mass spectrometry (GC-MS) was utilized for the identification of these targets, with the inclusion of borneol (BN) as an internal reference. This robust method was optimized and validated. It was found that the method showed good linearity in the range of 0.5-100 ng/mL and produced good recoveries (84.6 %-103 %) with satisfactory relative standard deviations (1.50 %-10.1 %). The determined limits of detection (LODs) for the group of four substances were found to vary from 0.3 to 0.9 ng/L, whereas the limits of quantitation (LOQs) exhibited variations between 1 and 3 ng/L. The subsequent implementation of this methodology to evaluate the four previously described off-flavor chemicals in tap water resulted in satisfactory results.