Trace Levels Research Articles

Integration of Samarium Vanadate/Halloysite Nanotubes: Electrochemical Determination of Furaltadone Using Flexible Electrode

In this study, a composite comprising a rare‐earth metal, samarium vanadate (SmVO4, SmV), anchored to halloysite nanotube (HNT) making SmV/HNT nanocomposite is synthesized for the sensitive electrochemical determination of furaltadone (FLD) through differential pulse voltammetry analysis based on the synergistic effect of SmV/HNT (the catalytic activity and chemical stability of SmV, which was further boosted by the improved surface area and conductance of HNT). Further, in the microscopic studies, it is revealed that SmV exhibits a tetragonal zircon‐type crystalline structure, with I41/amd (141) space group, whereas HNT comprises a multiphase kaolin composition as a gibbsite‐like octahedral sheet with multivalency, and the morphological irregularities of the individual constituents are rectified in the composite. The SmV/HNT composite is spray‐coated on polyethylene terephthalate sheet, which delivered a promising trace level limit of detection (0.009 μm) over a wide working range (0.05–194.4 μm) for FLD. Furthermore, real sample analysis is performed using human serum, and pharmaceutical tablet and the results reveal exceptional repeatability and sensitivity, indicating the real‐time application of SmV/HNT in the pharmaceutical domain.

High sensitivity and ultra-low detection limit of violet phosphorus-based formaldehyde gas sensor by ultrasonic-assisted laser ablation

Formaldehyde (HCHO) pollution has emerged as a progressively critical environmental concern, with the detection of formaldehyde at trace levels being an indispensable requirement. Violet phosphorus (VP) nanoplates, recognized as innovative two-dimensional materials, are promising candidates for gas sensing due to their rich active sites and substantial specific surface area. This work pioneered the use of ultrasonic-assisted laser ablation in the synthesis of VP nanoplates. The as-produced VP nanoplates had the lateral dimension of 6.5 μm and the thickness of 2–6 nm (1–5 layers), which was strongly influenced by the ablation techniques employed and the processing parameters. The VP nanoplates demonstrated excellent sensitivity towards formaldehyde: gauge factor is 7.23 × 109; and resistance response is 144.6 % for detecting 20 ppb of formaldehyde. The detection limit is only 3 ppb. This work employed experiments and calculations to study the sensing mechanism. The binding energy between VP/G and HCHO is −1.276 eV, demonstrating the strong chemical adsorption. This paper provided a novel approach to fabricate VP nanoplates with superior formaldehyde sensitivity and ultra-low detection limitation, thereby showcasing significant potential for applications in detecting of air pollution.

Facilitating inorganic arsenic speciation and quantification in waters: Polymer inclusion membrane preconcentration and X-ray fluorescence detection

BackgroundArsenic, classified as a priority pollutant and human carcinogen by the IARC, is subject to stringent regulatory limits in food and water. Among various arsenic species found in water samples, arsenite (As(III)) is identified as the most toxic form. Given the limitations of conventional spectroscopic techniques in speciation analysis, there is a crucial need for innovative and sustainable methodologies that enable arsenic speciation. Simplifying these methodologies is essential for widespread applicability and effective environmental monitoring. ResultsThis study proposes a simple and cost-effective analytical methodology for speciating inorganic arsenic in water samples. The method involves extracting As(III) into a polymer inclusion membrane (PIM) containing the extractant Cyanex 301 (bis(2,4,4-trimethylpentyl) dithiophosphinic acid), followed by analysis using energy dispersive X-ray fluorescence (EDXRF) spectrometry. The concentration of arsenate was measured after a reduction step using a thiosulfate/iodide mixture. This simple methodology allows a limit of quantification for trivalent arsenic (2 μg L−1), which is well below the World Health Organization's recommended maximum permissible level of As in drinking water (10 μg L−1). The method that is developed allows the determination of As at trace levels in waters with naturally occurring arsenic. Significance and noveltyThis study represents a significant advance in the field, providing a novel and efficient methodology for arsenic speciation analysis in water samples. By combining the advantages of polymer inclusion membrane (PIM) extraction with energy dispersive X-ray fluorescence (EDXRF) spectrometry, this study offers a cost-effective and environmentally friendly approach to address the critical issue of arsenic contamination in water sources, thereby contributing to enhanced environmental monitoring and public health protection.

Peteryoungia algae sp. nov. isolated from seaweeds of Gouqi Island, China, and its unique genetic features among Peteryoungia strains.

A Gram-stain-negative, light khaki, strictly aerobic, rod-shaped, motile via multiple flagella, and catalase- and oxidase-positive bacterium, designated as SSM4.3T, was isolated from the seaweed of Gouqi Island in the East China Sea. The novel isolate grows at 0-5.0% NaCl concentrations (w/v) (optimum 1%), pH 5.0-9.0 (optimum pH 7.0), and 15-37°C (optimum 30°C). The 16S rRNA gene sequences-based phylogeny indicates that the novel marine isolate belongs to the family Rhizobiaceae and that it shared the greatest sequence similarity (98.9%) with Peteryoungia rhizophila CGMCC 1.15691T. This classification was also supported by phylogenetic analysis using core genes. The predominant fatty acids (≥ 10%) of the strain were identified as C18:1 ω7c/C18:1 ω6c. Q-10 was identified as the major isoprenoid quinone, with trace levels of Q-9 present. The major polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The complete genome size of strain SSM4.3T is 4.39Mb with a DNA G+C content of 61.3%. The average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values between the genomes of strain SSM4.3T and its closely related representatives were 74.80-86.93%, 20.00-32.30%, and 70.30-91.52%, respectively. Phylogenetic analysis, grounded on the core genes, reveals the evolutionary relationship between SSM4.3T and other Peteryoungia strains. Pan-genomics analysis of 8 previously classified Peteryoungia species and SSM4.3T revealed their unique genetic features and functions. Overall, strain SSM4.3T was considered to be a new species of the Peteryoungia genus; the name Peteryoungia algae sp. nov. has been proposed, with type strain SSM4.3T (= LMG 32561 = MCCC 1K07170).

Exploring emerald global geochemical provenance through fingerprinting and machine learning methods

Emeralds – the green colored variety of beryl – occur as gem-quality specimens in over fifty deposits globally. While digital traceability methods for emerald have limitations, sample-based approaches offer robust alternatives, particularly for determining the geographic origin of emerald. Three factors make emerald suitable for provenance studies and hence for developing models for origin determination. First, the diverse elemental chemistry of emerald at minor (<1 wt%) and trace levels (<1 to 100’s ppmw) exhibits unique inter-element fractionations between global deposits. Second, minimally destructive techniques, including laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), enable measurement of these diagnostic elemental signatures. Third, when applied to extensive datasets, machine learning (ML) techniques enable the creation of predictive models and statistical discrimination with adequate characterization of the deposits. This study employs a carefully selected dataset comprising more than 1000 LA-ICP-MS analyses of gem-quality emeralds, enriched with new analyses. This dataset represents the largest available for global emerald deposits. We conducted unsupervised exploratory analysis using Principal Component Analysis (PCA). For machine learning-based classification, we employed Support Vector Machine Classification (SVM-C), achieving an initial accuracy rate of 79%. This was enhanced to 96.8% through the use of hierarchical SVM-C with PCA filters as our modeling approach. The ML models were trained using the concentrations of eight statistically significant elements (Li, V, Cr, Fe, Sc, Ga, Rb, Cs). By leveraging high-quality LA-ICP-MS data and ML techniques, accurate identification of the geographical origin of emerald becomes possible. These models are important for accurate provenance of emerald, and from a geochemical perspective, for understanding the formation environments of beryl-bearing pegmatites and shales.

Elemental analysis of valuable byproducts by TXRF spectrometry: coal fly ash and activated carbon

In order to ensure that byproducts are environmentally friendly and fit for purpose, their chemical composition must be determined, with special attention to elements at trace level. The large variability in the type of matrices demands a versatile analytical technique, compatible with sample preparation methods allowing both fast composition screenings and accurate quantitative analysis.In this work, byproducts derived from carbon-rich matrices, including coal fly ash and activated carbon from coconut and almond shells, were investigated by means of total reflection x-ray spectrometry and different sample preparations. Suspension, acid digestion, solid-liquid extraction and ashing were performed and assessed as to their complexity and detection capabilities, ranging from 0.01 mg/kg to 16 mg/kg, depending on the element and sample preparation. The internal standard quantification with gallium, aided by a variation of the standard additions method to take into account its possible presence in the samples, allowed to determine elements of environmental and technological interest, including K, Ca, Ti, V, Mn, Cr, Ni, Cu, Zn, Ga, As, Sr, Pb. Assets, limits and possible developments are presented and discussed.

Polydiacetylene Liposome-Based Dual-Output Optical Sensor for ppb Level Detection of Dopamine in Solution and Solid Phases.

Dopamine (DA), a neurotransmitter, plays a crucial role in regulating motor functions and emotions and can serve as a marker for several diseases. In this study, we report a highly sensitive polydiacetylenes (PDA)-based dual-output sensor for dopamine detection in both solution and solid phases that was developed by modifying PDA liposomes with boronic acid groups at the termini. This sensor exploits the high affinity between the catechol residue of dopamine and the -B(OH)2 group of the PDA-based probe (PDA-PhBA) to form boronate ester bonds, causing a stress-induced blue-to-red color change along with a steady increase in fluorescence response at λmax 622 nm. The PDA-PhBA-based sensor displays high sensitivity toward dopamine with low limit of detection of 6.2 ppb in colorimetric analysis and 0.6 ppb in fluorimetric measurements, demonstrating its dual optical output ability. The sensor works well for adrenaline, another catecholamine, with similar efficacy. Its practical applicability was validated by the successful recovery of trace level dopamine in blood serum and real water samples. Additionally, immobilizing PDA-PhBA liposomes in sodium alginate produced PDA beads for the solid-phase detection of dopamine with an limit of detection (LOD) of 59 nM (9.0 ppb) in colorimetric detection using a smartphone for capturing images and ImageJ software for analysis.

Ethylene Oxide: An Air Contaminant of Concern.

Ethylene oxide (EtO) is a colorless, flammable, reactive gas commonly used for sterilization and chemical manufacturing. It has become a contaminant of concern for the United States Environmental Protection Agency (USEPA) due to an assessment of its toxicity, which found that EtO is more potent than had been previously understood and which also revised the weight-of-evidence classification of EtO from "probably carcinogenic" to "carcinogenic to humans". With the revised toxicity assessment came findings of increased cancer risk to communities near some facilities that emit EtO to ambient air, including communities with environmental justice (EJ) concerns. To address EtO, the USEPA has conducted intensive research in recent years, centering its attention on measurement and sampling technology development, as well as monitoring of EtO in source emissions, near-source air, and atmospheric environments to further support science-based policy and regulations that reduce harmful impacts to human health. Research efforts by government, academic, and commercial institutions have resulted in the development of novel measurement and monitoring techniques, which has led to more robust characterization of EtO emissions and atmospheric levels across a wide range of concentrations, including trace levels (ppt). This Perspective covers the importance of capturing high quality, analytical measurements of EtO, what is known so far about these measurement technologies, EPA's response to the increasing concerns of EtO contamination, what still needs to be accomplished on the air quality front, and a focus on USEPA research and development moving forward.

Where did it go? A study of DNA transfer in a social setting

The sensitivity of DNA analysis has progressed to the point that trace levels of DNA, originating from only a few cells, can generate informative profiles. This means that virtually any item or surface can be sampled with a reasonable chance of obtaining a DNA profile. As the presence of DNA does not suggest how it was deposited, questions are often raised as to how the DNA came to be at a particular location and the activity that led to its deposition. Therefore, understanding different modes of DNA deposition, reflective of realistic forensic casework situations, is critical for proper evaluation of DNA results in court. This study aimed to follow the movements of DNA to and from individuals and common household surfaces in a residential premises, while socially interacting. This took place over an hour and involved four participants, with known shedder status, designated as visitors (a male and a female) and hosts (a male and a female), who engaged in the activity of playing a board game while being served food. During the study, the participants were instructed to use the toilet on a single occasion to assess the transfer of DNA to new and unused underwear that was provided. All contacts made by the participants in the dining room and kitchen were video recorded to follow the movements of DNA. Samples were collected based on the history of contact, which included hands, fingernails and penile swabs. Direct contacts resulted in detectable transfer (LR > 1) in 87 % (87/100) of the non-intimate samples and clothing. For surfaces touched by multiple participants, DNA from the person who made the last contact was not always detectable. The duration and number of contacts did not significantly affect the detection of the person contacting the item. On the other hand, presence of background DNA and participant’s shedder status appear to play an important role. Further, unknown contributors were detected in the majority of samples. Finally, indirect transfer was observed on a number of occasions including co-habiting partners of guests who were not present at the study location. The results of this study may assist with decision making for exhibit selection or targeting areas for sampling within the home environment. Our findings can also be used in conjunction with previous literature to develop activity-level evaluations in such situations where the source of the DNA is conceded, but the mode of deposition is disputed.

Hydrogen in the Deep Earth

Hydrogen is one of the most difficult elements to characterize in geological materials. Even at trace levels, hydrogen has a major impact on the properties of minerals, silicate melts, and fluids, and thus on the physical state of the mantle and crust. The investigation of H-bearing species in deep minerals, melts, and fluids is challenging because these phases can be strongly modified during transport to Earth’s surface. Furthermore, interpretation of experimental studies can be clouded by kinetic inhibitions and other artifacts. Nevertheless, recent improvements in analytical, experimental, and modeling methodologies have enabled advances in our understanding of how hydrogen is incorporated in the deep Earth, which is essential for constraining hydrogen cycling and storage through geologic time.

Development of SnO2 functionalized In2O3 porous microrods for trace level detection of formaldehyde at room temperature

Room temperature detection is a crucial objective in semiconductor sensor research, given its inherent benefits including reduced energy consumption, extended sensor lifespan, and significant reduction of safety hazards. Herein, novel room temperature sensing materials, SnO2-modified In2O3 porous microrods were synthesized, which exhibited exceptional sensing capability towards formaldehyde at room temperature. Specifically, the 5%-SnO2/In2O3 porous microrods demonstrate an impressive sensing response across varying formaldehyde concentrations, even at sub-ppm levels (0.1 ppm, 5.22), with a theoretical detection limit of 5.47 ppb, thereby enabling the detection of trace amounts of formaldehyde. Moreover, the sensors exhibit superior formaldehyde selectivity, rapid response characteristic, as well as good stability and reproducibility. The exceptional formaldehyde sensing ability of the SnO2/In2O3 sensor primarily arises from the creation of n-n heterojunctions at the SnO2/In2O3 interface, effectively modulating the interfacial potential. Additionally, the presence of SnO2 enhances the amount of surface-adsorbed oxygen species and active sites, thereby boosting sensing response. The porous rod-like structures further facilitate gas adsorption and diffusion, enhancing gas sensing capabilities. This work presents a novel strategy for constructing SnO2-In2O3 heterojunctions to achieve room-temperature formaldehyde detection.

Surface enhanced raman spectroscopy based sensitive and onsite detection of microplastics in water utilizing silver nanoparticles and nanodendrites.

Plastics, of the order of microns in size, being not visible to the naked eye, are one of the significant contributors to pollution in the environment. Thus, the detection of micron-sized plastics (microplastics (MPs)) is crucial because of its hazardous toxic effects on our surroundings. In this work, we have proposed a quick and on-site detection of MPs, such as, polyvinyl chloride (PVC), polyvinyl alcohol (PVA) and polystyrene (PS) at ultra trace level using surface-enhanced Raman spectroscopy (SERS). To detect and analyse the spectra, two different nanostructures, such as, spherical shaped Ag nanoparticles (NPs), and shape anisotropic Ag nano-dendrites (NDs) were utilised to acquire the SERS spectra. A comprehensive analysis was further performed to check and investigate the amount of enhancements due to the mentioned nanostructures. We observed the Ag NDs exhibited amplified signal intensity compared to the Ag NPs due to the shape anisotropy leading to the surface charge confinement effect to create highly dense hotspots. However, the spherical shaped polystyrene beads of micron size exhibited better enhancement in Raman signal intensity when mixed with Ag NPs due to increased surface adsorption with the NPs. Therefore, the comparative study emphasizes the ability of using solution-based nanostructure as SERS for the onsite detection of microplastics having diverge size range at low concentration.

Synthesis, characterization and As(III) scavenging behaviours of mango peel waste loaded with Zr(IV) ion from contaminated water

Raw mango peel (RMP) was first saponified to yield saponified mango peel (SMP), which was then loaded with Zr(IV) ions to form a biosorbent for As(III) scavenging.The biosorption behaviors and mechanisms of As(III) scavenging using RMP and Zr(IV)-loaded saponified mango peel (Zr(IV)-SMP) were investigated batchwise. The As(III) scavenging efficiency of RMP increased from 20.13 % to 87.32 % after Zr(IV) loading. Optimum contact time of 6 h has been investigated for As(III) scavenging by Zr(IV)-SMP, and the data on kinetics is well fitted to the pseudo-second-order (PSO) model. Similarly, isotherm data of Zr(IV)-SMP fitted well to the Langmuir isotherm model with the maximum As(III) scavenging potential of 45.52 mg/g. Chloride (Cl−) and nitrate (NO3−) have negligible influence on As(III) scavenging, but sulphate (SO42−) interferes significantly. The exhausted Zr(IV)-SMP could be easily regenerated by treating with 2MNaOH. A mechanistic study indicates that As(III) scavenging is primarily contributed to electrostatic interaction and ligand exchange, which is confirmed from both instrumental and chemical characterizations techniques. Tubewell underground water polluted with a trace amount of arsenic (98.63 μg/L) could be successfully lowered down to the WHO standard (10 μg/L) by applying a small amount of Zr(IV)-SMP. Therefore, the Zr(IV)-SMP investigated in this work can be a low-cost, environmentally benign, and promising alternative for scavenging trace levels of arsenic from contaminated water.

Detection of trace levels of selected allergic chemicals in commercial hair dyes in local market of Jeddah, Saudi Arabia

Hair dyes are now commonly used in Saudi Arabia, and other nations across the world, to cover up grey hairs and/or to modify the natural color of the hair. The principal ingredients of hair dyes are aromatic amines and phenols and which most likely cause allergic reactions, irritated skin, and even cancer in certain cases. Thus, the current study reports the separation and subsequent identification of four chemical constituents namely p-Phenylenediamine (PPD), 3-aminophenol (3AP), resorcinol (RES), and 2-methylresorcinol (2MRS) in 26 commercial hair dyes that represent ten famous brands available in the local market of Jeddah city, Saudi Arabia. High-performance liquid chromatography (HPLC) technique was successfully employed to identify the four chemical compounds using methanol-aqueous solution (10:90 v/v) containing diethanolamine (0.05 %) and ammonium acetate (0.02 M) at pH 5.2 as a proper mobile phase. The column was 150 × 4.6 mm ID and 5 µm Eclipse Plus C18 column and the retention times were 1.26, 3.16, 4.99 and 6.01 min for PPD, 3AP, RES, and 2MRS, respectively. The four standards PPD, 3AP, RES, and 2MRS at 254 nm displayed excellent linear calibration plots in the concentration range 5–100 µg/mL with acceptable correlation coefficients (R2) of 0.9964, 0.9980, 0.9952 and 0.9961, respectively. The low limits of detection (LOD) and quantification (LOQ) based on the standard deviation of the response and the slopes of the plots were found to be equal 7.17, 5.39, 8.33, and 7.47 µg/mL and 23.91, 17.97, 27.75, 24.89 µg/mL for PPD, 3AP, RES, and 2MRS, respectively.

Development of a Rapid Analytical Method on UV Spectrophotometer for Analysis of Trace Level APIs Telmisartan in Cleaning Validation Sample

Since the 1990’s, cleaning validations have gained a lot of interest within pharmaceutical and bio-pharmaceutical companies. In 1988, the FDA experienced its first major incident with cross contamination traceable to inadequate cleaning and cleaning validation. The finished drug product, Cholestyramine Resin USP, was recalled due to contamination with low levels of intermediates and degradants from the production of agricultural pesticides. The cross-contamination was believed to have come from the use of drums in the production of the active pharmaceutical ingredient (API). These drums had previously been used to store solvents for the manufacture of agricultural pesticides at another plant. Extra pure methanol procured from Chempura Enterprises Indore of make Merck and Analytical Grade water procured from the SK Traders Indore M.P. Reference materials, Telmisartan from Axiom Analytical Services Indore M.P. HPLC grade methanol (MeOH), HPLC Grade Water were purchased from Chempura Enterprises Indore M.P.. All chemicals were used as received, without any further purification. In recent years, increased emphasis has been placed in pharmaceutical companies for implementing robust validated cleaning procedures. The cleaning procedure is one of the most important tasks to avoid contamination and cross- contamination of APIs in pharmaceutical products manufactured on the same equipment trains. The cleaning procedures must be supported byappropriate analytical methods and related sampling methodologies.

Development of Al-MOF based pipette-tip solid-phase extraction approach for detection of fluoroquinolones in animal innards

Residues of fluoroquinolones (FQs) have been identified as a threat to food safety, highlighting the need for effective detection methods in food samples. This study utilized a hydrothermal synthesis method to create Al-based metal-organic framework (Al-MOF) for pipette-tip solid-phase extraction of FQs in food matrices. Coupled with HPLC-FLD, a novel sample pretreatment method for simultaneous detection of three FQs was developed, demonstrating good linearity (1−500 ng/g) with R2 values ranging from 0.9990 to 0.9998. Limits of detection and quantification were found to be 0.15−0.25 ng/g and 1.0−2.0 ng/g, respectively, with the relative standard deviations below 9.3 %. The extraction method showed promising results in animal liver and kidney samples, with a recovery rate of 75.2−103.6 %. Overall, this simple, rapid, and efficient method offers a valuable approach for analyzing trace levels of FQs in complex matrices.

Rapid detection of ricin at trace levels in complex matrices by asialofetuin-coated beads and bottom-up proteomics using high-resolution mass spectrometry

Ricin is a toxic protein regarded as a potential chemical weapon for bioterrorism or criminal use. In the event of a ricin incident, rapid analytical methods are essential for ricin confirmation in a diversity of matrices, from environmental to human or food samples. Mass spectrometry–based methods provide specific toxin identification but require prior enrichment by antibodies to reach trace-level detection in matrices. Here, we describe a novel assay using the glycoprotein asialofetuin as an alternative to antibodies for ricin enrichment, combined with the specific detection of signature peptides by high-resolution mass spectrometry. Additionally, optimizations made to the assay reduced the sample preparation time from 5 h to 80 min only. Method evaluation confirmed the detection of ricin at trace levels over a wide range of pH and in protein-rich samples, illustrating challenging matrices. This new method constitutes a relevant antibody-free solution for the fast and specific mass spectrometry detection of ricin in the situation of a suspected toxin incident, complementary to active ricin determination by adenine release assays.Graphical

Validation and measurement uncertainty of analytical methods for various azo dye adulterants in Curcuma longa L.

Food adulteration involving the illegal addition of dyes to foodstuffs has become an alarming issue in recent years. This study developed and validated a high-performance liquid chromatography (HPLC)-DAD (diode array detector) method for the simultaneous determination of nine azo dyes (Butter Yellow, Sudan Orange G, Para Red, Sudan I, Sudan II, Sudan III, Sudan IV, Sudan Red 7B, and Scarlet 808). Moreover, a qualitative analysis method using liquid chromatography-tandem mass spectrometry was developed to more accurately identify peaks detected in HPLC-DAD. The calibration curve represented good linearity (r2≥0.9998) over the measured concentration range of 0.5-25mg/kg. limit of detection and limit of quantification were 0.01-0.04 and 0.04-0.12mg/kg, respectively. Accuracy and precision were 96.0-102.6 and 0.16-2.01 (relative standard deviation%), respectively. Additionally, the measurement uncertainty and HorRat value were estimated. Several Curcuma longa L. distributed in Korea were collected and monitored for azo dye contaminants. PRACTICAL APPLICATION: The proposed HPLC-DAD method represents a significant advancement in the field, offering a reliable means of quantifying azo dyes and identifying their presence even at trace levels in adulterated turmeric. This not only contributes to ensuring the safety and integrity of turmeric products but also establishes precedent for robust analytical techniques in addressing food safety challenges.

Molecularly imprinted polymer based on covalent organic framework coated steel substrate as the mass spectrometric ionization source for the direct detect of aflatoxins in complex food matrices

Ambient mass spectrometry allows direct analysis of various sample types with minimal or no pretreatment. However, due to the influence of matrix effects, there are sensitivity and issues in analyzing trace analytes in complex food samples. In this work, we developed a spray mass spectrometry platform based on SSS@TPBD-TPA@MIPs (Stainless steel substrate (SSS), terephthalaldehyde (TPA), N, N, N′, N′-tetrakis(p-aminophenyl)-p-phenylenediamine (TPBD), molecularly imprinted polymer (MIP)), for rapid, in situ, high-throughput, highly enrichment efficiency and highly selective trace analysis of aflatoxins. By simplifying the sample pretreatment and directly applying high voltage for ESI-MS, the analysis can be completed within 1 min. The established method base on SSS@TPBD-TPA@MIPs exhibited high sensitivity and accuracy when determine trace level AFs in maize and peanuts. The results demonstrated a good linear relationship within the range of 0.01–10 μg/L, with the determination coefficient (R2) ≥ 0.9956. The limits of detection (LODs) was 0.035–0.3 ng/mL and limits of quantitation (LOQs) was 0.12–0.99 ng/mL, with acceptable recovery rate of 82.09–115.66 % and good repeatability represented by the relative standard deviation (RSD) less than 17.43 %. Furthermore, SSS@TPBD-TPA@MIPs exhibited excellent reusability, with more than 8 repeated uses, and showed good adsorption performance.

Molecular and eco-physiological responses of soil-borne lead (Pb2+)-resistant bacteria for bioremediation and plant growth promotion under lead stress

Lead (Pb) is the 2nd known portentous hazardous substance after arsenic (As). Being highly noxious, widespread, non-biodegradable, prolonged environmental presence, and increasing accumulation, particularly in arable land, Pb pollution has become a serious global health concern requiring urgent remediation. Soil-borne, indigenous microbes from Pb-polluted sites have evolved diverse resistance strategies, involving biosorption, bioprecipitation, biomineralization, biotransformation, and efflux mechanisms, under continuous exposure to Pb in human-impacted surroundings. These strategies employ a wide range of functional bioligands to capture Pb and render it inaccessible for leaching. Recent breakthroughs in molecular technology and understanding of lead resistance mechanisms offer the potential for utilizing microbes as biological tools in environmental risk assessment. Leveraging the specific affinity and sensitivity of bacterial regulators to Pb2+ ions, numerous lead biosensors have been designed and deployed worldwide to monitor Pb bioavailability in contaminated sites, even at trace levels. Besides, the ongoing degradation of croplands due to Pb pollution poses a significant challenge to meet the escalating global food demands. The accumulation of Pb in plant tissues jeopardizes both food safety and security while severely impacting plant growth. Exploring Pb-resistant plant growth-promoting rhizobacteria (PGPR) presents a promising sustainable approach to agricultural practices. The active associations of PGPR with host plants have shown enhancements in plant biomass and stress alleviation under Pb influence. They thus serve a dual purpose for plants grown in Pb-contaminated areas. This review aims to offer a comprehensive understanding of the role played by Pb-resistant soil-borne indigenous bacteria in expediting bioremediation and improving the growth of Pb-challenged plants essential for potential field application, thus broadening prospects for future research and development.