Trace Levels Research Articles

Synthesis of the modified SBA-15 mesoporous silica with TAN ligand to preconcentrate and determine trace amounts of Ni (II) ions in water and wastewater samples.

The synthesis of modified mesoporous silica (SBA-15), a powerful and highly effective adsorbent, was provided for the preconcentration, extraction, separation, and determination of trace amounts of Ni (II) ions. In this method, SBA-15 modified with 1-(2-thiazolylazo)-2-naphthol (TAN) was used as a suitable absorbent. The absorption of Ni (II) ions was studied using the FAAS technique. Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), energy-dispersive spectroscopy (EDS), Fourier-transform infrared (FT-IR) spectroscopy, and CHNS elemental analysis techniques were used to assess the characteristics of SBA-15 and TAN/SBA-15. Effective parameters (pH, amount of nanocomposite, extraction time, and type of recovery solvent) for extracting Ni (II) ions via TAN/SBA-15 were investigated. The merit figures of the method were obtained with appropriate results, such as detection limit, accuracy, enrichment factor, and preconcentration factor. The calibration curve was linear within the range of 5.0-50ngmL-1 with a detection limit of 1.8ngmL-1. High preconcentration, small relative standard deviations, and enrichment factors (approximately 100) were represented by the statistical analysis. The proposed method for measuring Ni (II) ions was used at trace levels in real samples, such as seawater, river water, well water, and wastewater from a textile factory, an electrical power station, an MDF factory, and a food industrial company, with satisfactory results.

Supramolecular Solvent Liquid Phase Microextraction of Voriconazole İn Pharmaceutical and Environmental Samples With High Performance Liquid Chromatography Detection

In this study, a new analytical method based on the supramolecular solvent liquid phase microextraction (Ss-LPME) and HPLC was developed for the analysis of voriconazole as an active drug in the class of antifungals with a wide spectrum of action at trace levels. Nano/micro sized supramolecular phase formed in 1-decanol, tetrahydrofuran and aqueous environment was used as extraction agent for separation and preconcentration of trace level of voriconazole. For the optimization of the Ss-LPME method, important analytical parameters such as the effect of sample solution pH, volume of 1-decanol, amount of THF, ultrasounic irridation time, centrifugation time and sample solution volume on the extraction efficiency were evaluated. Optimal conditions of the Ss-LPME; pH: 8, 1-decanol volume: 200 µL, THF volume: 300 µL, ultrasounic irridation time:10 min and centrifugation time: 8 min. For the developed Ss-LPME/HPLC procedure, the limit of detection (LOD), limit of quantification (LOQ) and enhancement factor (EF) were found 2.7 µg·L-1, 8.8 µg·L-1 and 36, respectively. The Ss-LPME/HPLC procedure was applied to waste water, lake water and drug samples. The fact that recovery values ranging from 100% to 108.5% were obtained for these real samples proved that this method can be used successfully in the matrix environments studied

Non-enzymatic detection of versatile anti-oxidant in diverse media using 3D spinel nickel cobalt oxide with 2D tungsten carbide nanohybrid heterostructure electrocatalyst

Diphenylamine (DPA), an organic amine derivative compound widely used in agriculture and polymer industries as an anti-scaling and anti-oxidising agent. The excessive and prolonged usage of DPA in agricultural products would result in the accumulation of it. The poor degradation ability and associated health hazards marked it as a “contaminant of emerging concern”. Since DPA is not completely banned in many countries, measuring the trace levels of DPA is essential to ensure the safety of the ecosystem. Therefore, the electrochemical sensing method was applied for the precise detection of an infinitesimal concentration of this component. In this work, we have prepared a spinel nickel cobalt oxide with a tungsten carbide (NCO/WC) electrocatalyst-based electrochemical sensor for the accurate detection of DPA. The structural, and morphological details were examined with Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscope (FE-SEM), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analyses. The electrochemical properties were evaluated with impedance and voltammetric measurements. Various voltammetric techniques were utilized to assess the efficiency of NCO/WC towards DPA. Significantly, our sensor displayed a low detection (0.001 µM), and low quantification (0.0048 µM) limits, good linear range (0.01 to 147 µM), optimal sensitivity (1.716 µA µM−1 cm−2), remarkable selectivity, appreciable repeatability, reproducibility, and stability performance outcomes. Then, the sensor was employed to monitor the DPA in various matrices like agricultural, environmental, and human samples and conquered astonishing results. These findings suggest that our NCO/WC-based electrochemical sensor is a promising platform for the enhanced detection of DPA.

Ion-selective electrode based on polyurethane-immobilized di-(2-ethyl hexyl) phosphoric acid for low-concentration aqueous Pb2+ detection and quantification

This study used a polyurethane (PU)-based ion selective electrode (ISE) immobilized with di-(2-ethyl hexyl) phosphoric acid (D2EHPA) to detect and quantify Pb2+ ions at low concentrations (10−10 to 10−1 M) in aqueous solution. PU, synthesized from castor oil (Ricinus communis L.), was utilized as the ISE membrane matrix. The ISE demonstrated a sensitivity of 26.24 ± 0.12 mV/decade, a detection limit of 1.44 × 10−7 M, and a response time of 10 s. We maintained the measurement stability for up to six days of storage.The results of Pb2+ quantification produced by ISE were compared with the results using atomic absorption spectroscopy (AAS), indicating similar Pb2+ concentrations in both artificial and real wastewater samples (calculated t-value < theoretical t-value). Therefore, this ISE is suitable for detecting trace levels of Pb2+ and quantifying them with high accuracy.

Novel plant extract-chitosan nanocomposite (SCE/ChNPs) biosensor for trace level arsenic sensing in water samples using quartz crystal microbalance with dissipation monitoring

Abstract Arsenic contamination in water poses a severe threat to human health and the environment, necessitating the development of sensitive, selective, and eco-friendly detection methods. This study unveils a groundbreaking approach for ultra-low arsenic detection in water by combining the unique properties of Saussurea costus ethanolic extract and chitosan nanoparticles in a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) based biosensor. The Saussurea costus extract, rich in bioactive compounds, was loaded onto chitosan nanoparticles to leverage their synergistic effects. The prepared Saussurea costus ethanolic extract loaded chitosan nanoparticles (SCE/ChNPs) were extensively characterized using various techniques, including atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). The results revealed a mean particle size of 37.0 ± 2.0 nm, a spherical shape, a negative surface charge (-28.3 mV), a porous structure, and an amorphous crystalline nature. The QCM-D technique enabled real-time monitoring of mass changes on the quartz crystal sensor surface upon interaction with arsenic species. The biosensor's analytical performance was evaluated, demonstrating high sensitivity, selectivity, and repeatability for ultra-low arsenic detection. This innovative green biosensor technology offers a sustainable, efficient, and accessible solution for safeguarding public health and the environment from arsenic contamination.&amp;#xD;

Innovative hierarchical porous hydrophilic molecularly imprinted resin for high-throughput detection of perfluorocarboxylic acids in milk using 96-well plate SPE-LC-MS/MS

The accumulation of perfluorocarboxylic acids (PFCAs) in environment and foods represents a significant threat to public health due to the long-term ingestion of contaminated food. This study introduces a novel adsorbent, the hierarchical porous hydrophilic molecularly imprinted resin (HPHMIR), which was synthesized by integrating molecular imprinting techniques with hydrophilic resins. The HPHMIR, characterized by its extensive mesoporous structure (average pore width ∼9.71 nm) and favorable imprinting factors (2.6–5.0), facilitates the effective adsorption of PFCAs from complex matrices through multiple interaction mechanisms, including hydrogen bonding and electrostatic interactions. This innovative material was employed in a 96-well plate format for solid-phase extraction (SPE), and combined with LC-MS/MS, a high-throughput method for the determination of PFCAs in milk was developed. The proposed method demonstrated exceptional performance, including excellent linearity (0.48–240 ng mL−1; r ≥ 0.9986), low detection limits (0.04–0.11 ng mL−1), high precision (relative standard deviation ≤ 9.9 %), and satisfactory recovery (75.7–118.1 %). These results highlight the efficacy of the method in extracting trace levels of PFCAs from complicated sample matrices, presenting a promising alternative for monitoring PFCA contamination and advancing public health standards.

Development and Validation of an ICP‐OES Method to Determine Extractable and Leachable Metals in HDPE (Plastic) Pharmaceutical Packaging Material

ABSTRACTThe safety and effectiveness of pharmaceutical medicines depend heavily on extractables and leachables. Patients may be adversely affected by contaminants that enter drug products through packing materials. As a result, regulatory organizations like the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) have set standards and regulations for evaluating and managing extractables and leachables. Characterizing the packing materials, carrying out extraction experiments and checking the extracted solutions for contaminants are all parts of this research. As part of the process for approving new drugs, regulatory agencies make use of these data. In present work, an inductively coupled plasma optical emission spectroscopy (ICP‐OES) method is developed and validated for quantifying trace elements from a high‐density polyethylene (HDPE) packaging material. The approach delineated in accordance with United States Pharmacopoeia (USP) &lt;661.1&gt; and &lt;661.2&gt; for the comprehensive analysis of 16 metallic elements including aluminium, arsenic, cadmium, chromium, cobalt, lead, mercury, nickel, titanium, vanadium, zinc, zirconium, barium, manganese, calcium and tin is applicable for evaluating the efficacy of packaging materials. The method detection limits (MDLs) complied as per USP 39‐NF 34 &lt;661.1&gt; along with relative standard deviations (RSDs) obtained were ranging from 0.3% to 3.1% and recoveries of all elements spiked at two different trace levels in HDPE samples were within 97%–110%, providing sensitive, accurate and reproducible methodology.

Development and Validation of a Novel Method Using QuEChERS and UHPLC-MS-MS for the Determination of Multiple Emerging Fungicides in Surface Waters

The increasing global reliance on pesticides for agricultural pest control has raised significant environmental concerns, particularly due to inadequate monitoring of emerging chemicals in surface waters. This study addresses the potential contamination of aquatic ecosystems by developing and validating a method for detecting trace amounts of four recently registered fungicides: three succinate dehydrogenase inhibitors (fluopyram, penthiopyrad, pydiflumetofen) and fluopicolide, a structurally related fungicide. Employing QuEChERS-based sample extraction combined with ultra-high-performance liquid chromatography (UHPLC-MS-MS), this method achieves detection limits of 0.1 to 0.2 μg/L, with recovery rates between 90% and 110%, and intra-day relative standard deviation values well within the acceptable range of less than 20%. Applied to surface grab water samples from the greater Melbourne area, Australia, the method successfully identified all four fungicides at trace levels, including a notable high concentration of fluopyram (7.3 μg/L) during autumn, with the others intermittently detected at lower concentrations. This study represents the first documented instance of quantifiable detections of these four fungicides in Australian surface water systems. Given their high toxicity to several organisms and the limited global data on these substances, our findings underscore the critical need for continuous monitoring to inform strategies to safeguard aquatic ecosystems from these chemicals.

Micronutrient availability alters Candida albicans growth and farnesol accumulation: implications for studies using RPMI-1640.

The dimorphic fungus Candida albicans is a major opportunistic pathogen of humans. RPMI-1640 is a chemically defined growth medium commonly used with C. albicans. We identified over 32,000 publications with keywords RPMI and C. albicans. Additionally, Antifungal Susceptibility Testing (AFST) protocols in the United States (CLSI) and Europe (EUCAST) utilize RPMI as a base media to assess drug efficacy against clinical fungal isolates. RPMI contains many nutrients but no added trace metals. We found that the growth characteristics with RPMI were dependent on which MOPS buffer was chosen and the contamination of that buffer by trace levels of Mn(II) and Zn(II). Added Mn(II) was most needed for cell growth while added Zn(II) was most needed for secretion of farnesol and other signaling molecules.

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.

Non-enzymatic g-C3N4 supported CuO derived-biochar based electrochemical sensors for trace level detection of malathion

Malathion (MALA), a widely used insecticide, even at trace levels exhibits deleterious effects towards respiratory tracts, and nervous system, necessitating its detection. Herein, we have offered non-enzymatic trace level monitoring of MALA using g-C3N4 supported CuO-derived biochar. The present B-CuO/g-C3N4 based electrochemical sensor is synthesized using hydrothermal approach followed by calcination at high temperature. The result unveiled the strong <pi-pi> interactions, high charge separation efficiency, significant porosity leading to excellent electrochemically active surface area 9.88 × 10−5 cm2 with least charge transfer resistance (RCT) value of 35.2 K Ω. The B-CuO/g-C3N4 based nanocomposite offered excellent complex formation ability with MALA and square wave anodic stripping voltametric method (SWASV) generates an enhanced electrochemical signal due to oxidation of MALA. Following all necessary optimizations, the sensor was capable to exhibit limit of detection (LOD) value of 1.2 pg mL−1 with R2 = 0.968. The modified biosensor offered its potential towards detection of MALA in apple and tomato samples with a recovery ranging from 87.64 to 120.59%. This novel B-CuO/g-C3N4 ternary nanocomposite provides non-enzymatic detection of MALA having excellent electrochemical properties and hence opens new pathways for exploring the use of biochar in other electrochemical applications.

Real time monitoring of heavy metal adulteration in biodiesel using Arduino UNO platform@A promising multi-purpose stimuli-responsive azomethine based chemoreceptor for hierarchical tri-ionic sensing

The presence of metallic adulteration even in very trace level may lead to deleterious impact on the biodiesel quality and ultimately may be responsible for the dropping down of system efficiency, which necessitates the trace level recognition of heavy metal adulteration from biodiesel. In this context, herein using an azomethine functionalized chromogenic chemoreceptor, 1-((E)-(4-hydroxyphenylimino) methyl) napthalen-2-ol (HMN) has been reported for the selective chemodosimetric recognition of Cu2+ with a lower detection threshold of 7.8 ppb via distinct chromogenic variation of HMN. In addition to this, it has also exhibited selective and reversible naked eye chromogenic sensing behaviour towards F− (LOD=160 ppb) and Al3+ (LOD=48 ppb) at very trace level, which is quite lower than the WHO permissible limit. Distinct chromogenic recognition of F− by HMN proceeds via strong intermolecular hydrogen bonding mediated improved intramolecular charge transfer. The spectroscopic response of HMN in alternate presence and absence of the targeted analytes made it suitable to formulate AND-NOT-XNOR-NAND-OR gate based ‘Castle-like’ complicated logic circuitry. In-vitro cell imaging study using A549, human lung carcinoma cell line attests intracellular recognition capability of HMN, demonstrating its effectual bio-medicinal applications. Interestingly, inspired by the capability of HMN towards recognition of copper from biodiesel specimen, an RGB-assisted device comprised of TCS color sensor and an Arduino UNO 8-bit microcontroller has been developed for real-time quantitative analysis of the biodiesel adulteration. Going one step further, utilization of lab-on-a-box based prototype to monitor the concentration-dependent chromogenic fluctuation via RGB analysis is undoubtedly beneficial for the determination of copper adulteration in biodiesel sample. The presently developed chemoreceptor can thus be regarded as a valuable addition in the field of supramolecular chemistry as well as a significant initiative towards regular monitoring of the biodiesel quality control parameters as a part of sustainable environment.

Simultaneous multianalyte trace-level quantification of eight genotoxic nitrosamine impurities in valsartan Active Pharmaceutical Ingredient and tablet formulation using UFLC-MS/MS and greenness assessment

Valsartan, a widely prescribed antihypertensive drug, was identified for the presence of carcinogenic nitrosamine impurities in 2018, leading to product recalls worldwide and necessitating sensitive liquid and gas chromatographic methods for trace level detection of nitrosamine impurities. This study developed and validated an ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method for the quantification of eight genotoxic nitrosamines (NDMA, NDEA, NDPA, NEIPA, NDIPA, NMBA, NDBA, and NMPA) in valsartan drug substance and tablet formulations. The method employed a triple quadrupole analyzer, atmospheric pressure chemical ionization (APCI) ionization source and multiple reaction monitoring (MRM) scan mode for the analysis. Chromatographic separation was achieved on a Phenomenex biphenyl column (150 × 4.6 mm, 3 µm) maintained at 55 °C. The mobile phase consisted of a binary gradient of solvent A (0.1 % formic acid in water) and solvent B (0.1 % formic acid in methanol), with a total run time of 20 min for the sensitive and specific detection of the analytes. Method validation demonstrated excellent linearity, recovery, precision, and sensitivity. The greenness of the developed analytical method was critically assessed through comprehensive evaluations using the GAPI, AGREE, and AES metrics and the results obtained are compared with the reported methods in the literature. This novel UFLC-MS/MS method offers a reliable and sensitive approach for routine quality control analysis of nitrosamine impurities in Valsartan drug substance and tablet formulations.

Biophysical evidence that frostbite is triggered on nanocrystals of biogenic magnetite in garlic cloves (Allium sativum)

Trace levels of biologically precipitated magnetite (Fe3O4) nanocrystals are present in the tissues of many living organisms, including those of plants. Recent work has also shown that magnetite nanoparticles are powerful ice nucleation particles (INPs) that can initiate heterogeneous freezing in supercooled water just below the normal melting temperature. Hence there is a strong possibility that magnetite in plant tissues might be an agent responsible for triggering frost damage, even though the biological role of magnetite in plants is not understood. To test this hypothesis, we investigated supercooling and freezing mortality in cloves of garlic (Allium sativum), a species which is known to have moderate frost resistance. Using superconducting magnetometry, we detected large numbers of magnetite INPs within individual cloves. Oscillating magnetic fields designed to torque magnetite crystals in situ and disturb the ice nucleating process produced significant effects on the temperature distribution of supercooling, thereby confirming magnetite’s role as an INP in vivo. However, weak oscillating fields increased the probability of freezing, whereas stronger fields decreased it, a result that predicts the presence of magnetite binding agents that are loosely attached to the ice nucleating sites on the magnetite crystals.

Determination of dimethyl sulfate genotoxic impurity in pantoprazole sodium sesquihydrate by derivatization method and UPLC/MS

In this study, a new method has been developed and, the method has been validated to analyze dimethyl sulfate (DMS) which known as a genotoxic impurity. DMS has been detected in trace levels within the drug substance pantoprazole sodium sesquihydrate using the derivatization method. Triethylamine has been used as derivatization reagent. Due to the highly polar nature of the derivatization product, which is a quaternary ammonium ion, a polar retention Hilic column has been used for chromatographic separation. The Waters QDA detector has been used in the single ion recording (SIR) mode at m/z 116 for the detection of the quaternary ammonium ion. In this study, the recovery rates have been achieved within the range of 96.46–105.98%. The LOD has been determined as 1.94E-07 mg/mL, and the LOQ has been determined as 6.46E-07 mg/mL. From the results, it can be said that the improved method in this study, would enables fast and reliable solutions for routine quality control analyses for DMS in API companies that especially is producing PSS.

Material Characterisation of 19–20th Century Manuscripts from Northern Thailand

Abstract Material analysis was carried out on four manuscripts from Northern Thailand, which included two palm-leaf manuscripts and two paper manuscripts. The two palm-leaf manuscripts MS 6 and MS 7 were found to have been written in the traditional method, wherein text was incised on the surface of the leaves, and then soot applied to the surfaces, confirmed by the identification of carbon ink. MS 7 additionally showed the presence of trace levels of iron in the ink, either from soot paste or from the stylus used for inscribing. The paper manuscript MS 3 was written in iron-gall ink, with sections written using a methyl-violet based ink while MS 4 was written in carbon ink. The paper used in the case of MS 3 was found to be machine made, while khoi fibres (Streblus asper) were used for making the paper used for MS 4. A combination of traditional and modern pigments, like molybdenum orange, was used for decorating the edges and cover. The results improved our understanding of these manuscripts in particular, and also provided us with insights about the rapid adoption of modern materials and their incorporation into the production of written artefacts from Northern Thailand in the late 19th and early 20th centuries.

Interrogation of a fluoropolymer dispersion manufactured with a non-fluorinated polymerization aid for targeted and non-targeted fluorinated residuals by liquid chromatography high resolution mass spectrometry

Recent advances in fluoropolymer polymerization have focused on replacing perfluorinated polymerization aids (PAs) with hydrocarbon-based alternatives. Hydrocarbon PAs are vulnerable to fluorinated radicals during polymerization, leading to the creation of hundreds of process-specific polyfluorinated residuals. These residuals, which include low molecular weight extractable or leachable impurities, are challenging to detect at trace levels. This study investigates a polytetrafluoroethylene (PTFE) dispersion prepared with a hydrocarbon-based surfactant (DOSS) to measure these process-specific fluorinated residues. Liquid chromatography high resolution mass spectrometry is one of the few analytical methods that offers the sensitivity and selectivity required to detect these residuals in complex matrices at concentrations as low as parts per billion. The results indicate that using a hydrocarbon PA during emulsion polymerization produces numerous polyfluorinated residuals. These must be identified and monitored to develop effective abatement strategies, ensuring responsible fluoropolymer manufacturing.

Efficient and fast arsenate removal from water by in-situ formed magnesium hydroxide

MgO nanoparticles have good As-adsorption capacity in treating As-contaminated wastewater but suffer from high production cost. In this study, instead of using pre-formed MgO nanoparticles, we found that in-situ formed Mg(OH)2 from MgCl2 and NaOH reaction exhibited super high arsenate (As(V)) removal efficiency. Only 1.5 mmol/L of in-situ formed Mg(OH)2 could remove more than 95% As(V) within 10 min to make the As contaminated water (10 mg-As(V)/L) meet the municipal wastewater treatment standard, whereas MgO nanoparticles failed. The Mg-As sludge has an amorphous crystal structure while no Mg(OH)2 phase could be observed. As(V) existed uniformly within the sludge which was confirmed by elemental mapping. A precipitation-adsorption-coagulation mechanism might exist, which could relieve the restriction of limited surface area of solid MgO adsorbents. This study not only reveals an applicable method for efficient removal of trace level As(V) from water but also implies the huge potential of in-situ formed adsorbents in water treatment.

Simultaneous detection of enrofloxacin and chloramphenicol antibiotics using surface-enhanced Raman spectroscopy combined with triangular silver nanoplates

The emergence of antibiotic residues in the environment and food requires the development of sensitive and selective detection methods for monitoring these contaminants. In fact, many different types of antibiotics will be used simultaneously to prevent diseases in livestock and aquatic animals, causing antibiotic residues in food and the environment. Rapid and accurate simultaneous analysis of multiple antibiotics at low concentrations remains a major challenge in in the field of rapid detection. This study presents a sensitive and selective method for the simultaneous detection of two widely used antibiotics, enrofloxacin and chloramphenicol, by combining surface-enhanced Raman spectroscopy (SERS) with triangular silver nanoplates. Triangular silver nanoplates (TAgNPls) in the form of colloid were simply synthesized by chemical reduction method and then used as an effective SERS substrate, enhancing the Raman signals of the target antibiotics and enabling the detection of these antibiotics at trace levels. It was found that with a SERS substrate assembled from the above TAgNPls, the antibiotics enrofloxacin and chloramphenicol could be detected with detection limits of 2.6 µg/L and 4.3 µg/L, respectively. In addition, this SERS substrate also allows simultaneous detection of the above two antibiotics in one analytical sample with concentrations as low as 10 µg/L for both substances. The proposed method holds promise for addressing concerns related to antibiotic contamination in various environments and food sources, contributing to the advancement of analytical techniques for the trace detection of pharmaceutical residues.

Removal of Trace Cu2+ from Water by Thermo-Modified Micron Bamboo Charcoal and the Effects of Dosage

Chronic copper intoxication via drinking water induces diseases and physiological toxicity. Bamboo charcoal has been applied in the treatment of copper (Cu2+) in water. However, the adsorption by micron bamboo charcoal (MBC) of trace Cu2+ in tap drinking water and the underlying factors behind it have not been sufficiently reported. In this study, to improve the adsorption by MBC of trace levels of Cu2+ in drinking water, MBC was thermo-modified and characterized. Through batch experiments, the adsorption equilibrium was analyzed, and isotherm models were simulated. The removal rates and the optimization were investigated through a general full factorial design including the thermo-modified temperature (MT), initial concentration (C0), and dosage. The results indicated that the thermo-modification significantly improved the removal by MBC of Cu2+ at trace level C0. The satisfactorily low level of 0.12 ± 0.01 mg⋅L−1 was achieved in the range of C0 from 0.5 to 2.0 mg⋅L−1 within the short contact time of 0.5 h. The processes conformed to the Freundlich and Langmuir adsorption isothermal models at a C0 lower than 4.0 mg⋅L−1 and higher than 8.0 mg⋅L−1. The correlation between C0 and dosage played an important role in the removal of Cu2+. This work proposes the application of the ecofriendly material MBC and an optimization mode in the removal of trace Cu2+ from tap drinking water. It is also revealed that the positive and negative correlation and the “critical point” of the removal rate with dosage depend on the initial concentrations.