On-site Analysis Research Articles

On-site analysis of the turquoise artifacts excavated from the Xingong site in Beijing

On-site analysis of the turquoise artifacts excavated from the Xingong site in Beijing

Photothermal Desorption and Reagent-Assisted Low-Temperature Plasma Ionization Miniature IT-MS/MS for On-Site Analysis of Illicit Drugs in Saliva and Urine.

Globally, drug-impaired driving fatalities now exceed those from drunk driving, urging the need for on-site and roadside detection methods. In this study, a photothermal desorption and reagent-assisted low-temperature plasma ionization miniature ion trap mass spectrometer (PDRA-LTP-ITMS) was developed for on-site detection of drug-impaired driving. The pseudomultiple reaction monitoring (MRM) in PDRA-LTP-ITMS enables continuous ion selection during ion introduction and improved sensitivity to nearly 3-fold compared with the conventional full scan mode. The PDRA-LTP integrated the ionization source and photothermal desorption region into the LTP tube with a volume of 0.05 mL. Photoionization and Penning ionization from LTP discharging facilitate proton transfer reactions with the dopant and produce characteristic [M + H]+ for drugs. Dopants of butanol and acetone were separately employed to enhance the thermal desorption and ionization efficiency, resulting in a 2.6-fold sensitivity increase. Saliva and urine samples were collected with a medical swab, and only 10 μL of sample is required for each analysis. The sample is rapidly heated to 250 °C using a halogen lamp and analyzed within 5 s. With these designs, a 4-fold and 10-fold increase in sensitivity was achieved compared to APPI and nano-ESI, respectively. The limits of detection (S/N = 3) of illicit drugs, including MDMA, MDA, methamphetamine, amphetamine, ketamine, and cocaine, in saliva ranged from 4.5 pg μL -1 to 20 pg μL-1 and met the threshold values of GA1333-2017. The performance of the PDRA-LTP-ITMS was even comparable to that of LTQ-Orbitrap Velos Pro ETD MS, providing a novel method of rapid on-site drug-impaired driving analysis.

Survey of Opportunities for Coal to Nuclear Conversion in Texas

This technical report aims to provide energy developers and policymakers with information and preliminary analyses on the potential for Texas coal plant sites to be repurposed for nuclear power. Investigation into coal-to-nuclear (C2N) has shown that constructing a nuclear reactor on the site of a retired coal plant has both economic and environmental benefits. The data presented includes operational details of the coal power plants, the presence of nearby hazards, geological and hydrological data, and population statistics. This information was gathered for 19 coal powered electricity generation sites in Texas. Thirteen of the sites assessed have no hazards or other factors that would disqualify them from hosting a Small Modular Reactor (SMR). Of these, 11 sites are also suitable for a Light Water Reactor (LWR). The smaller size and power output of SMRs makes these additional 2 sites possible, even near a population center. The remaining 6 coal plant sites would require more specific on-site analysis or potential adjustments to the reactor design to be considered for licensing. These findings exhibit the potential for cost effective nuclear development to benefit grid stability and provide baseload power to Texas.

Innovative Infrared Spectroscopic Technologies for the Prediction of Deoxynivalenol in Wheat.

Mycotoxin contamination in cereals is a global food safety concern. One of the most common mycotoxins in grains is deoxynivalenol (DON), a secondary metabolite produced by the fungiFusarium graminearum and Fusarium culmorum. Exposure to DON can lead to adverse health effects in both humans and animals including vomiting, dizziness, and fever. Hence, the development of analytical technologies capable of predicting mycotoxin contamination levels in grains is crucial. In this study, we emphasize innovative infrared (IR) spectroscopic technologies for the prediction of DON in wheat along the food supply chain. The performance of an IR laser spectroscopic platform for on-site or laboratory confirmative analysis was evaluated. Furthermore, the performance of a handheld IR spectrometer for preliminary screening during transportation, storage, or harvesting was assessed. The accuracy of cross validation (AccCV) obtained with the laser spectrometer reached 92%, while the handheld IR spectrometer achieved 84.6%. Hence, both technologies prove significant potential for rapid mycotoxin detection.

Feasibility of on-site CT-FFR analysis on cardiac photon-counting CT in evaluation of hemodynamically significant stenosis in comparison to invasive catheter angiography.

Coronary CT angiography (CCTA) is an excellent tool in ruling out coronary artery disease (CAD) but tends to overestimate especially highly calcified plaques. To reduce diagnostic invasive catheter angiographies (ICA), current guidelines recommend CT-FFR to determine the hemodynamic significance of coronary artery stenosis. Photon-Counting Detector CT (PCCT) revolutionized CCTA and may improve CT-FFR analysis in guiding patients. In this single-center study, patients with obstructive CAD who underwent CCTA using PCCT and subsequent ICA were included. Delta CT-FFR was calculated by subtracting the CT-FFR values 1.8cm before and after the stenosis, with a cut-off value of ≥0.06 indicating hemodynamic significance. Revascularization during ICA defined a stenosis as hemodynamically significant. Sensitivity, specificity, negative and positive predictive value, and diagnostic accuracy of Delta CT-FFR have been determined. Patients were followed up to evaluate the rate of major adverse cardiovascular events (MACE) 6months after CCTA. A total of 28 patients (3 female, median age 68years) were enrolled in this study. Delta CT-FFR was pathological in all patients who underwent revascularization. No patients with normal Delta CT-FFR required stent placement. In 39.29% of the cases, calculation of Delta CT-FFR could have prevented patients from undergoing unnecessary ICA. The positive predictive value of Delta CT-FFR for CAD RADS 4a was 66.7%, negative predictive value 100%, and diagnostic accuracy 74%. Delta CT-FFR analysis using PCCT offers a feasible tool in identifying hemodynamically significant coronary artery stenosis and can help to reduce purely diagnostic ICA.

Hydroxyl Spillover in Fe-Se Dual-Site Catalysts for Mixed Plastics Assay.

The complex composition of real plastic wastes poses a significant challenge for their large-scale disposal. A responsive on-site compositional analysis of plastics is informative in choosing downstream processing methods. Nanocatalyst-based assay kit is highly qualified for this scene; however, there remain no efficient nanocatalysts for plastics due to their highly inert chemistry. Herein, we first unveiled the hydroxyl spillover effect in an Fe-Se dual-site catalyst (FeSe/NC) and devised a prototype colorimetric assay kit for mixed plastics. Experimental and theoretical results unveiled that Fe sites acted as the main active sites for H2O2 activation to produce adsorbed hydroxyl (*OH) intermediates, which subsequently desorb as hydroxyl radicals (•OH) and transfer to Se sites, supports, and even plastics for further catalysis. Specifically, •OH transferred to different plastics shows varying activities, where signal outputs were hereby used as the fingerprint for plastic identification. Moreover, the remaining *OH could respond to redox interferences in the samples for enhanced accuracy. In contrast to traditional techniques involving precise apparatus and complex pretreatments, our approach enables a rapid assay (∼10 min) of raw powdery mixed plastic wastes with an ultralow cost (0.0012 $). This discovery fills a crucial gap in the plastic assay, offering new technical guidance for diverse upcycling and recycling strategies to tackle the global plastic waste crisis.

Power-Sustainable and Portable Electrochemical Sensing Platforms for Complex Outdoor Environment Applications.

Portable sensor technologies are indispensable in personalized healthcare and environmental monitoring as they enable the continuous tracking of key analytes. Human sweat contains valuable physiological information, and previously developed noninvasive sweat-based sensors have effectively monitored single or multiple biomarkers. By successfully detecting biochemicals in sweat, portable sensors could also significantly broaden their application scope, encompassing non-biological fluids commonly encountered in daily life, such as mineral water. However, developing a portable electrochemical sensing system with sustainable power remains a challenge for real-time, on-site analysis in complex outdoor applications. Here, we present a power-sustainable and portable electrochemical sensing platform, composed of multiple electrochemical sensors, a multichannel data acquisition circuit, a microfluidic module, and a power supply module, that is designed to conform onto the human body for daily use. The device enables simultaneous and selective measurement of Na+, K+, and pH levels in sweat and outdoor environments wirelessly. Additionally, we utilize a dual power supply module composed of a lithium-ion battery and a solar cell, offering a sustainable power supply for various application scenarios. Looking forward, this novel platform can serve as a bridge between monitoring biological fluids and detecting nonbiological fluids in complex outdoor environments.

Portable Self-Powered/Colorimetric Dual-Mode Sensing Platform Based on Multifunctional Bioconjugates for Precise On-Site Detection of Acetamiprid.

Neonicotinoid insecticides have been widely applied in modern agriculture to improve crop productivity, but their residues have adverse impacts on the environment and human health. Hence, to address these issues, a portable self-powered/colorimetric dual-mode sensing platform was developed for the simple, rapid, precise, and sensitive on-site detection of acetamiprid (ATM) residues in vegetables. In this case, a multifunctional bioconjugate with specific recognition capability, excellent enzyme-like activity, and loading capacity is the key to the sensing design. Using an Eppendorf (EP) tube as a miniaturized laboratory, the bioconjugates and the colorimetric test strip were integrated into the EP tube, and combined with a nanozyme-based self-powered sensing platform (with an area of 1.5 × 1.5 cm2), accurate on-site detection of ATM was achieved, with detection limits as low as 2.9 fg·mL-1 (self-powered method) and 31.5 fg·mL-1 (colorimetry), respectively. Notably, we simulated the actual insecticidal situation based on the field application concentration and quantified the pesticide residues in vegetables. The relative errors of our method and the standard high-performance liquid chromatography method were 0.15% (the self-powered method) and 1.8% (colorimetry), respectively. The portable dual-mode sensing platform with high sensitivity and accuracy opened up a new avenue for the development of on-site pesticide residue analysis in the next generation of agricultural products.

Optical and Electrical Dual-Mode Detection of a Carcinogenic Substance Based on Synergy of Liquid Crystals and Ionic Liquids.

Visual, sensitive, and selective detection of carcinogenic substances is highly desired in portable health protection and practical medicine production. However, achieving this goal presents significant challenges with the traditional single-mode sensors reported so far, as they have limited sensing mechanisms and provide only a single output signal. Here, we report an effective optical and electrical dual-mode sensor for the visual, sensitive, and selective detection of N-nitrosodiethylamine (NDEA), a typical volatile carcinogenic substance, leveraging the synergy of ionic liquid-doped liquid crystals (IL-LC). The optical mode derived from LCs provides the sensor with a visual identification recognizable by the naked eye, while the electrical mode derived from ILs offers a quantitative detection capability. It is noteworthy that the synergistic effect of the IL and LC enhances the performance of both optical and electrical modes. Unique sensing mechanisms derived from the interaction between NDEA and IL-LC endow the sensor with excellent selectivity. As a proof of concept, a portable kit based on a dual-mode sensor has been developed for the real-time and on-site analysis of N-nitrosamine impurities in pharmaceuticals. This work provides valuable insights and a theoretical foundation for developing portable multimode chemical sensors.

A fully integrated microfluidic cartridge for rapid and ultrasensitive nucleic acid detection from oropharyngeal swabs.

Rapid and accurate molecular diagnostics are crucial for preventing the global spread of emerging infectious diseases. However, the current gold standard for nucleic acid detection, reverse transcription polymerase chain reaction (RT-PCR), relies heavily on traditional magnetic beads or silica membranes for nucleic acid extraction, resulting in several limitations, including time-consuming processes, the need for trained personnel, and complex equipment. Therefore, there is an urgent need for fully integrated nucleic acid detection technologies that are simple to operate, rapid, and highly sensitive to meet unmet clinical needs. In this study, we developed a novel, integrated microfluidic cartridge featuring a unique needle-plug/piston microvalve, which enables stable long-term reagent storage and flexible liquid handling for on-site nucleic acid analysis. Coupled with in situ tetra-primer recombinase polymerase amplification (tp-RPA), we achieved highly sensitive nucleic acid detection with a remarkable limit of detection of 20 copies per mL (0.02 copies per μL) and a short turnaround time of less than 30 minutes. To validate this assay, we tested 48 oropharyngeal swab samples. The positive detection rate reached 64.58% (31/48), significantly exceeding the approximately 50% positive detection rate of the traditional RT-PCR method. Furthermore, our assay demonstrated a 100% concordance rate with RT-PCR in detecting positive samples. Thus, we believe our microfluidic nucleic acid analysis system represents a promising approach for enabling rapid and ultrasensitive nucleic acid detection of pathogenic microorganisms in resource-limited settings and low-income areas.

An integrated microfluidic platform for on-site qPCR analysis: food allergen detection from sample to result.

Improving food safety is crucial in the context of a "One Health" approach. To guarantee product quality and safety, the food industry, which has a very high turnover rate, needs short time-to-result analyses. Therefore, user-friendly systems at the point-of-need are necessary, presenting relevant analytical information and fulfilling the current regulations. To answer these challenges, a microfluidic platform integrating sample preparation and subsequent multiplex qPCR detection has been developed for on-site testing. The system consists of a fully automated instrument driving a microfluidic cartridge dedicated to the detection of multiple allergens in complex food matrices. The first part of the microfluidic cartridge contains pumps, reservoirs, valves and a filter to achieve DNA extraction, concentration and purification. Multiplex qPCR detection is carried out in the second part of the cartridge including a negative control chamber and five chambers for target analyte detection. The in-house developed instrument contains all functions to autonomously drive the microfluidic cartridge: pneumatic control for fluid actuation, thermal control for qPCR amplification and an optical system using three fluorescent wavelengths for multiplex detection of the target analytes and controls. We demonstrate the simultaneous detection of four different allergens - gluten, sesame, soy and hazelnut - from various complex food matrices. The turn-around-time from sample to result is close to two hours and controls in place validate the obtained results. For gluten, a direct comparison with ELISA shows that the regulatory threshold of 20 ppm is comfortably fulfilled. Moreover, all results are in agreement with external laboratory analyses performed in parallel on the same samples. Our findings confirm that the system can be used safely on-site without the risk of cross contamination between the various samples being analysed. In conclusion, our microfluidic platform offers a robust method for on-site allergen management.

A length-band fluorescence-based paper analytical device for detecting dipicolinic acid via ofloxacin complexation with Cu2.

Dipicolinic acid (DPA) is a key biomarker of bacterial spores. In this study, we present a novel distance-based paper analytical device (d-PAD) for the fluorescence sensing of DPA. The detection mechanism relies on the complexation of ofloxacin (OFL) with Cu2+ ions, where Cu2+ quenches the fluorescence of OFL via static quenching. Upon the introduction of DPA, it interacts with the OFL-Cu2+ complex, resulting in an enhanced fluorescence signal from OFL. The assay demonstrated a limit of detection (LOD) of 0.08 μM over a range of 0.6-120 μM, as measured using a spectrofluorometer. The d-PAD was designed for efficient reagent transport through capillary action on paper substrates, allowing for rapid on-site DPA analysis without requiring advanced laboratory equipment. The length of the fluorescent bands on the d-PADs was proportional to the concentration of DPA, providing a simple and effective readout method. With a sensitivity of 0.6 μM, the device shows a strong response to varying DPA concentrations. This distance-based platform offers a straightforward and quantitative approach to result interpretation, making it a promising tool for detecting bacterial spores in real samples. The development and optimization of this paper-based microfluidic assay represent a significant step forward in portable diagnostic technologies.

Machine learning-integrated droplet microfluidic system for accurate quantification and classification of microplastics.

Microplastic (MP) pollution poses serious environmental and public health concerns, requiring efficient detection methods. Conventional techniques have the limitations of labor-intensive workflows and complex instrumentation, hindering rapid on-site field analysis. Here, we present the Machine learning (ML)-Integrated Droplet-based REal-time Analysis of MP (MiDREAM) system. Utilizing a compact peristaltic pump, the system achieved high-throughput droplet generation (> 200 Hz) while encapsulating MPs in uniform droplets (142 ± 8 μm). A high-resolution complementary metal oxide semiconductor (CMOS) sensor combined with an optimized YOLO v8 ML model was employed for real-time analysis, achieving a mean average precision (mAP) of 0.982 and an area under the curve (AUC) of 97.64 %. Comparative analysis with hemocytometer counting and surface-enhanced Raman spectroscopy (SERS) demonstrated the superior performance of the system, demonstrating high correlation (R² = 0.9965) and minimal deviation (6.36 %) from theoretical values. The system accurately classified MPs of different sizes, achieving accuracies of 95.4 %, 87.9 %, 95.3 %, 85.3 %, and 92.5 % for 3, 5, 10, 30, and 50 μm particles, respectively. Validation with real-world water samples confirmed the system adaptability, while maintaining high detection accuracy (> 90 %). The on-site field tests of MiDREAM system also demonstrated its robust performance for environmental monitoring in a variety of environments. Therefore, our portable and integrated MiDREAM system offers a promising solution for real-time environmental monitoring applications.

A paper-based SERS/colorimetry substrate for reliable detection.

For on-site analysis, the combination of surface enhanced Raman scattering (SERS) and colorimetry, as a dual-mode detection, can effectively improve the accuracy of detection, and reduce the influence of instrument fluctuation, which greatly improves the accuracy and reliability of the results. However, the preparation of SERS/colorimetry substrates are usually time-consuming and costly, which limits their practical applications. In this paper, a hydrophobic paper-based SERS/colorimetry substrate can be prepared by a simple spraying method. The hydrophobicity is introduced by the structures formed with polydimethylsiloxane and polymethylmethacrylate, which leads to high detection sensitivity due to its enrichment effect. Moreover, the electrostatic interaction between Ag nanoparticles and the analytes further enhances the performance of SERS and colorimetry in detection of thiram and aspartame. It also provides a new method for the detection of aspartame with colorimetry. Finally, the detection limits of SERS and colorimetry for thiram and aspartame are 0.1 mg/L and 0.1 g/L, 1mg/L and 0.1g/L, respectively. The paper-based SERS/colorimetry substrate makes the results more reliable through dual-mode detection, which shows great potential in the detection of real samples.

A new oligothiophene-based turn-on fluorescent probe for rapid, visual and ultrasensitive monitoring of hypochlorite in real-life samples

Excessive level of hypochlorite (ClO−) can cause the oxidation of biomolecules including DNA, proteins and RNA, even damage vital organ. Thus, developing effective detecting techniques is of great need to monitor ClO− levels. Herein, a new turn-on fluorescent probe 3TD based on oligothiophene was constructed to effectively detect ClO− in real-life samples. Probe 3TD showed attractive sensing properties toward ClO− with high specificity, strong anti-interference, ultrasensitivity (detection limit: 9.8 nM), ultrarapid response (40 s), and wide applicable pH range (4–10). Interestingly, 3TD was applied for visual and daily on-site monitoring of ClO− in lettuce, kumquat, rice, onion and sprouted potato, and the 3TD-based test strips were also used for rapid, sensitive, visual on-site monitoring of ClO−, providing a reliable and convenient approach for visual on-site analysis. Importantly, 3TD was capable of sensitive monitoring of ClO− levels in water, disinfectants, bio-fluids, vegetables, fruits, and dairy products with high precision, offering an effective means for ultrasensitive monitoring of ClO− in real-life samples.

Sensitive ratiometric detection of Fumonisin B1 using a reusable Ag-pSi SERS platform.

Food and agricultural commodities endure consistent contamination by mycotoxins, low molecular weight fungal metabolites, which pose severe health implications to humans together with staggering economic losses. Herein, a ratiometric aptasensor was constructed using silver-coated porous silicon (Ag-pSi) used as an efficient surface-enhanced Raman scattering (SERS) substrate. The bioassay included direct detection of fumonisin B1 (FB1), an abundant and widespread contaminant, by a specific aptamer sequence immobilized on the porous transducer. The inherent surface void and pore morphology were physically optimized to achieve a sufficient SERS effect (enhancement factor>5×107). Under optimal conditions, the aptasensor exhibits high sensitivity, wide dynamic range, signal stability, selectivity and regeneration for consecutive FB1 detection (0.05ppb, 0.1-1000ppb, RSD of 5.2%, no interference with competing mycotoxins and eight regeneration cycles, respectively). The efficacy of the designed aptasensor was elucidated in various spiked matrices (maize, onion, wheat and milk) with averaged recovery values of 93.3-113.6% and satisfactory consistency with HPLC data for representative foodstuffs. Overall, the resulting validation emphasizes the transducer's reliability and suitability for practical use, including on-site analysis.

Smartphone-aided fluorescent probe combining lateral flow assay for Cys testing in food and organism.

Combining the fluorescent probe, smartphone and lateral flow assay (LFA) to form a new detecting system, which will meet the requirements of rapid, convenient and on-site analysis of Cys. In this study, BDP-SINO based on BODIPY was developed and displayed high signal-to-noise ratio (363-fold) and fast response speed (1.0min) for monitoring Cys. Simultaneously, BDP-SINO was successfully utilized to determine Cys in various liquid and solid extraction samples. With the assistance of a smartphone, BDP-SINO loaded test strips and microporous filter membranes could be utilized for portable, real-time visualization and quantitative detection of Cys. Furthermore, the combination of smartphone, linear discriminant analysis (LDA), and LFA provided new detecting system for qualitative detection of Cys. Besides, BDP-SINO had good biocompatibility and was able to fluorescently image Cys in living cells and mice. In summary, the detection system based on BDP-SINO realized identification of Cys in diverse application scenarios.

Research on the Failure Mechanism and Treatment Technology of Landslides in Typical Accumulation Bodies Along Highways in Qinghai Province

Landslides on the Jiaxi Highway in Qinghai Province threaten construction safety and quality. The on-site data analysis shows that excavation at the foot of the slope and heavy rainfall are the key factors causing the displacement of the Q1 monitoring point by 1825 mm. This article uses numerical simulation methods combined with the strength reduction method to study the stability changes of slopes under different working conditions. Numerical simulations identified the landslide location and predicted a 1960 mm slip and a safety factor of 1.26 under natural conditions, indicating risks. The study adopted a strategy combining slope cutting, load reduction, and sheet pile wall reinforcement. After the first treatment, the safety factor rose to 1.83 with a 40 mm displacement; after the second, it reached 2.36 with a 37 mm displacement. Continuous monitoring showed a 50 mm displacement over six months, indicating stability. Rainfall simulations before and after treatment explained the stability evolution and local slope stability. Treatments increased the safety factor to 2.16 with a 17.6 mm displacement. This study significantly improved highway landslide stability and verified treatment effectiveness, providing a reference for similar geological conditions.

Improved Point-of-Care Mass Spectrometry Analysis with Thin-Layer Chromatography-Based Two-Dimensional Separation and Spray Ionization.

Point-of-care testing (POCT) involves administering rapid on-site analysis to provide fast biochemical testing results. POCT reduces delays in clinical decision-making and eliminates the need to transport and prepare clinical samples for immediate diagnosis or clinical intervention by healthcare professionals. Herein, a novel methodology integrating thin-layer chromatography-based two-dimensional separation with miniature mass spectrometry was developed for rapid on-site clinical analysis. As a proof-of-concept demonstration, γ-aminobutyric acid, 2-hydroxyglutarate, and N-acetyl-l-aspartic acid, which are widely known as biomarkers for brain gliomas, were selected as model analytes for method development and validation. The proposed approach exhibited satisfactory analytical performance, with 1 ng/mL limits of detection, 2 ng/mL limits of quantitation, and recoveries in the range of 85.9-107.2%. Additionally, on-TLC derivatization and reactive spray ionization strategies were utilized to enhance the mass spectrometric signals compared to underivatized analysis. This method was applied to analyze clinical samples, showcasing its attractive potential outside the laboratory.

Development of a Dual-Readout Multicolor Immunoassay for the Rapid Analysis of Isocarbophos in Vegetable and Fruit Samples.

Multicolor immunoassay is a powerful tool for rapid analysis without the use of bulky instruments owing to various color conversions, which is suitable for on-site visual analysis for pesticides. Herein, this study developed a multicolor immunoassay for the rapid detection of isocarbophos. After competitive immunoassay, the secondary antibody (GAM-ALP) catalyzed ascorbyl-2-phosphate (AAP) into ascorbic acid (AA). The AA can reduce K3[Fe(CN)6] into K4[Fe(CN)6]. The latter can react with Fe3+ to form Prussian blue; otherwise, the orange AAP-Fe3+ complex was generated. Therefore, the multicolor immunoassay achieved a color conversion of orange-green-blue in response to isocarbophos, allowing for rapid semiquantitative analysis by the naked eye. After parameter optimization, the multicolor immunoassay was developed depending on the ratiometric absorbance between the Prussian blue and AAP-Fe3+ complex. Moreover, a smartphone was used to measure the RGB value of the color conversion for the development of portable visual, quantitative analysis. Both the absorbance-based and RGB-based multicolor immunoassays showed good accuracy and practicability in the recovery test. This study provided a common approach for the development of dual-readout multicolor immunoassay, which can be used for on-site rapid screening by quantitative or visual semiquantitative analysis.