Detection Limit Of Method Research Articles

Influence of statistical methods on lower limits of dose estimation in biological dosimetry

Purpose In cases of radiological or nuclear events, biological dosimetry enables decisions whether an individual was exposed to ionizing radiation and the estimation of the dose. Several statistical methods are used to assess uncertainties. The stringency of the applied method has an impact on the lowest dose that can be detected. To obtain reliable and comparable results, it is crucial to harmonize the applied statistical methods. Materials and methods The decision threshold and detection limit of the statistical methods were derived for variable cell numbers. The coverage of the 95% confidence intervals as well as the false-positive and false-negative rates of the methods were compared based on simulations. The evaluated methods included a graphical method, the propagation of errors and a Bayesian method. Results The minimum resolvable doses, the doses at the detection limit and the coverage were relatively variable between the compared methods. The Bayesian method showed the best coverage, lowest resolvable doses and had false-positive rates close to 5%. The graphical method with the combination of two 83% confidence intervals also showed promising results. The other methods were either too conservative or underestimated the uncertainties for some doses or cell numbers. Conclusions The assessment of the lower dose limits is a central part of biological dosimetry and the applied statistical methods have a strong influence on the interpretation of the results. Simulations enable comparisons between methods and provide important information for the harmonization and standardization of the uncertainty assessment.

One-pot MCDA-CRISPR-Cas-based detection platform for point-of-care testing of severe acute respiratory syndrome coronavirus 2

Compared to quantitative real-time PCR (q-PCR), CRISPR-Cas-mediated technology is more suitable for point-of-care testing (POCT) and has potential for wider application in the future. Generally, the operational procedure of CRISPR-Cas-mediated diagnostic method consists of two independent steps, the reaction of signal amplification and the CRISPR-Cas-mediated signal detection. Complex multi-step procedures can easily lead to cross-contamination. To develop a convenient and rapid method for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection, we propose a MCTOP method (Multiple cross displacement amplification-CRISPR-Cas12b-based testing in one-pot), which targets the open reading frame 1ab (ORF1ab) and nucleocapsid protein (N) gene of SARS-CoV-2. This method combines MCDA isothermal amplification and CRISPR-Cas-mediated sequence-specific detection into a one-pot reaction. The optimal reaction was achieved with isothermal amplification of 40 min and CRISPR-Cas-based detection of 15 min, both at 64°C. Then, the results can be visualized by the real-time fluorescence instrument and also lateral flow biosensor. The lowest detection limit of the proposed method is 10 copies of each of target sequences, and it has no cross-reactivity with non-SARS-CoV-2 templates. In a clinical test of 70 pharyngeal swab samples, MCTOP assay showed a specificity of 100% and sensitivities of 98 and 96% for the real-time fluorescence instrument and lateral flow biosensor, respectively. The MCTOP developed in this study is a rapid, convenient, highly sensitive, and specific method for SARS-CoV-2 nucleic acid detection. It can be used as an effective point-of-care testing (POCT) tool for clinical diagnosis and epidemiologic surveillance of SARS-CoV-2 infections, especially suitable for the basic, field and clinical laboratory.

Development of a colorimetric/fluorescence dual-mode immunoassay for aflatoxin B1 based on streptavidin-induced gold nanoparticle aggregation.

Adual-mode immunoassay method was developed for colorimetric and fluorescence detection of aflatoxin B1 (AFB1) based on streptavidin-induced gold nanoparticle aggregation (AuNP@SA). AuNP-modified streptavidin-biotin labeling AFB1 complete antigen aggregations (AuNP@SA@Bio-BSA-AFB1) were synthesized as the competitive binding and dual-mode probe. AuNP@SA@Bio-BSA-AFB1 aggregations possessed high colorimetric and fluorescence quenching intensities. AFB1 antibodies modified immunomagnetic microspheres were used as the capture probe. The competitive binding between AFB1 and AuNP@SA@Bio-BSA-AFB1 leads to changes in color and fluorescence intensity. The detection limit of the colorimetric method is 6.95ng·mL-1, while that ofthe fluorescence method is 0.07ng·mL-1. The practicality of the proposed strategy was demonstrated bydetermining AFB1 in spiked peanut samples.

Dispersive solid phase extraction of 18 PFAS from environmental water samples using a novel MOF-polymeric monolith composite followed by High-Resolution mass spectrometry analysis

Metal-organic frameworks (MOFs) have been broadly coupled with many pretreatment techniques due to their remarkable attributes including high porosity, significantly increased specific surface area, and chemical stability, but their nanoscale dimensions make their handling challenging. To overcome this, a novel MOF-polymeric monolith composite was synthesized and studied as a novel sorbent material in an analytical technique. A rapid and efficient method for the extraction of a mixture of 18 per- and poly-fluoroalkyl (PFAS) compounds from environmental water samples was established based on MOF-polymeric monolith composite assisted dispersive solid phase extraction (d-SPE). The analytical methodology was carried out with the aid of liquid chromatography tandem high-resolution mass spectrometry. Several parameters influencing the extraction efficiency were comprehensively evaluated and optimized. The optimization was based on two processes: the one-variable-at-a-time approach (OVAT) and the central composite design (CCD). Preliminary studies were conducted and the extraction and elution time, as well as the sample volume were evaluated by adopting OVAT approach. The optimal parameters were found to be 15 min for extraction time, 5 min for the elution time and 10 mL as sample volume. Under the optimum conditions, the sample pH, sorbent amount and eluent volume were all evaluated under the design of experiments (DoE). ANOVA demonstrated the suitability of the suggested model with a p-value of less than 0.05 and various diagnostic tests validate the well-fitting results. The software extracted the optimal conditions which were pH = 7, sorbent amount = 10 mg and eluent volume = 750 μL. The method was subsequently validated with respect to accuracy, linearity detection limits and reproducibility. The proposed method presented recoveries over 70 %, method detection limits 1–46 ng/L and relative standard deviations <20 %. Before the implementation of the method in real samples, the “green” character was evaluated using the ComplexGAPI index, indicating the satisfactorily “green” character of the new MOF-based dSPE-LC-HRMS method. Finally, the efficacy of the method for determining PFASs in four environmental water matrices was tested using several matrices of varying complexity, including wastewater effluent, river water, marine water, and runoff.

Detection and assessment of post-earthquake functional building ceiling damage based on improved YOLOv8

Ceiling is one of the crucial non-structural components in public buildings, but it is susceptible to damage after earthquakes. For important functional buildings, rapid assessment of their safety, economic losses, and recoverability is crucial post-earthquake. However, the current detection and assessment of ceiling damage in earthquake-stricken areas heavily relies on manual efforts. Due to limitations in detection methods and technological levels, these manual efforts struggle to meet the requirements of speed, accuracy, and safety. In response to these challenges, this study proposes a post-earthquake functional building ceiling damage detection and assessment method based on GTS-YOLOv8. Firstly, a dataset containing 1059 real ceiling damage images is established, categorized into two damage types: “Panels Fallen" (PF) and “Complete Destruction" (CD). Next, Ghost convolution is introduced, combined with Swin Transformer blocks, and a novel Slim Neck structure is designed to enhance the YOLOv8 algorithm. The GTS-YOLOv8 object detection model is presented. On the established dataset, GTS-YOLOv8 achieves 92 % mAP50 and 72.2 % mAP50-95, surpassing the baseline YOLOv8 by 2.3 % and 4.1 %, respectively. The study investigates ceiling damage detection under different lighting conditions and shooting distances. The results indicate that the highest detection accuracy is achieved under well-lit conditions and when the shooting perspective covers the entire ceiling area. Finally, based on the research outcomes, a detection and assessment architecture is constructed, and a corresponding system is developed, capable of automatically determining the damage State based on ceiling damage detection results. This architecture provides a foundation for the rapid assessment of building safety, economic losses, and recoverability post-earthquake.

A Novel Fluorescent Chemosensor for Sensitive and Rapid Determination of Pb(II) Ions in Aqueous Environments.

This investigation devised an eco-friendly spectrofluorometric Pb(II) ion measurement approach. To determine Pb(II) ions, a polymeric fluorescence sensor membrane with excellent selectivity has been developed. It contains photoinitiators, functional monomers that can be cured under UV radiation, and cross-linking agents. After the characterization of the membrane, the most suitable parameters for the measurement of Pb(II) ions were determined. The measurement was performed in a short time-roughly 40s-at emission and excitation wavelengths of 488nm and 277nm, respectively, at pH 6.0. The developed method's detection limit was calculated as 1.42 × 10- 9 mol L- 1, and its calibration range was recorded as 4.83 × 10- 9 to 9.66 × 10- 8 mol L- 1. Recovery studies and the sensor's stability, lifetime, and repeatability have been evaluated. Real sample applications have been implemented using wastewater samples. The suggested approach may be used to quickly and accurately determine Pb(II) ions at low concentrations with good selectivity and sensitivity.

Intensive Spatiotemporal Characterization of the Tire Wear Toxin 6PPD Quinone in Urban Waters.

6PPDQ is a tire-derived contaminant toxic to coho salmon (LC50 = 41-95 ng/L) found widely distributed in urban environments. Most monitoring efforts have relied on relatively few discrete samples collected at select locations across rain events. Early work has revealed that 6PPDQ concentrations vary widely over time and space, raising questions about when and where to collect samples. Here, we employ condensed phase membrane introduction mass spectrometry, a high-throughput analysis approach to characterize spatiotemporal variability of 6PPDQ in urban streams. Analytical method detection limits of 0.3-8 ng/L and a duty cycle of 2.5 min/sample enabled high-throughput adaptive sampling. Temporal sampling revealed dynamic 6PPDQ concentrations, with significant changes occurring over minutes during peak rainfall. Spatial variability was characterized at multiple sites along three watercourses during the first significant precipitation of autumn 2023 on central Vancouver Island, B.C., Canada. Site-specific concentrations suggest attenuation of 6PPDQ after point source inputs by some combination of physical (dilution, sorption) or chemical (degradation) processes. This is the first report of an intensive sampling campaign describing the spatiotemporal distribution of 6PPDQ, highlighting the need for careful consideration of sampling strategies to evaluate the risk and impact of 6PPDQ in urban waterways.

Ionizing Radiation Dose to the Skin Assessed after Rapid Detection of 232Th in Consumer Products.

After some consumer products indicated elevated levels of 232Th progeny by gamma-ray spectrometry, a microwave digestion and inductively coupled plasma-mass spectrometry (ICP-MS) procedure was implemented for the direct assay of 232Th content to ensure compliance with Federal regulations and guidelines. Levels of 232Th were determined by ICP-MS based on standard calibration using a 205Tl internal standard. The method had a method detection limit (MDL) of 0.15 Bq g-1 and a lower limit of quantification (LLOQ) of 0.65 Bq g-1 for 232Th, making it a suitable confirmatory method following gamma-ray spectrometry. The 232Th activity concentration calculated from the ICP-MS results ranged from 2.0-3.4 Bq g-1 for the kinesiology tape samples and 20 Bq g-1 for the silicone ion bracelet. The VARSKIN+1.0 software program was used to calculate the shallow dose equivalent of ionizing radiation from 232Th and its progeny from the ICP-MS results. The skin dose to the consumer wearing the kinesiology tape ranged from 0.48-1.6 mSv y-1. The skin dose to the consumer with constant wear of the silicone ion bracelet was estimated to be 17 mSv y-1. Although 232Th may be determined indirectly by assay of high abundance gamma rays produced by its progeny, the US Code of Federal Regulations (CFR) requires the direct assay of 232Th for confirmatory analysis. We found this ICP-MS method to be a rapid 232Th confirmatory technique compared to a chemical separation followed by alpha spectrometry procedure.

Metformin improves HPRT1-targeted purine metabolism and repairs NR4A1-mediated autophagic flux by modulating FoxO1 nucleocytoplasmic shuttling to treat postmenopausal osteoporosis.

Osteoporosis is a major degenerative metabolic bone disease that threatens the life and health of postmenopausal women. Owing to limitations in detection methods and prevention strategy awareness, the purpose of osteoporosis treatment is more to delay further deterioration rather than to fundamentally correct bone mass. We aimed to clarify the pathogenesis of postmenopausal osteoporosis and optimize treatment plans. Our experiments were based on previous findings that oxidative stress mediates bone metabolism imbalance after oestrogen deficiency. Through energy metabolism-targeted metabolomics, we revealed that purine metabolism disorder is the main mechanism involved in inducing oxidative damage in bone tissue, which was verified via the use of machine-learning data from human databases. Xanthine and xanthine oxidase were used to treat osteoblasts to construct a purine metabolism disorder model. The activity and differentiation ability of osteoblasts decreased after X/XO treatment. Transcriptomic sequencing indicated that autophagic flux damage was involved in purine metabolism-induced oxidative stress in osteoblasts. Additionally, we performed serum metabolomics combined with network pharmacology to determine the pharmacological mechanism of metformin in the treatment of postmenopausal osteoporosis. HPRT1 was the potential target filtered from the hub genes, and FoxO1 signalling was the key pathway mediating the effect of metformin in osteoblasts. We also revealed that SIRT3-mediated deacetylation promoted the nuclear localization of FoxO1 to increase the expression of HPRT1. HPRT1 upregulation promoted purine anabolism and prevented the accumulation of ROS caused by purine catabolism to reverse oxidative damage in osteoblasts. We propose that purine metabolism disorder-induced oxidative stress is important for the pathogenesis of postmenopausal osteoporosis. The therapeutic mechanism of metformin should be confirmed through subsequent drug optimization and development studies to improve bone health in postmenopausal women.

Development and validation of a multicompound LLE–LC–MS/MS method for biomonitoring of hazardous medicinal products in urine of exposed workers

Antineoplastic drugs are carcinogens, mutagens, or teratogenic substances, which can pose serious risks to professionals. Concerns about chronic exposure to these hazardous medicinal products (HMPs) have led to their prominence in the EU strategic framework on health and safety at work 2021-2027. To estimate and mitigate human exposure to HMPs, regular monitoring programs and, consequently, reliable, sensitive, multicomponent methods are crucial. In this study, an unconventional liquid-liquid extraction coupled with liquid chromatography–tandem mass spectrometry analysis is proposed to simultaneously identify and quantify seven HMPs of high concern in urine: cyclophosphamide, etoposide, ifosfamide, paclitaxel, megestrol, mycophenolate mofetil, and tamoxifen, the last three for the first time. Recoveries of all drugs from urine samples were close to 100%, and method detection limits (0.6–4.1ng/L) were noticeably lower than most previously reported. This novel, non-invasive method for biomonitoring is thus suitable to unequivocally identify the target drugs at the expected trace levels in urine and to infer about workers' exposure. The method contributes to the conception of regular monitoring programs for antineoplastic drugs, in line with recommendations under EU Directive 2004/37/EC. This is especially relevant in Portugal, where neither analytical methods nor exposure data exist due to lack of formal surveillance.

A simple and low-cost method for determination of methanol in alcoholic solutions

Methanol poisoning can occur through consumption of methanol-containing alcohols, especially in areas where production, distribution, sale and consumption of alcohol is lawfully prohibited. Due to its toxic potency, determination of methanol in alcoholic solutions is important. The aim of the present study was to develop a rapid, simple and inexpensive method for quantification of methanol in alcoholic solutions that uses minimal equipment available in most laboratories. The method developed is based microdistillation and chromotropic acid, which can be conducted without sophisticated instruments or personal. The system consists of a micro-tube suspended in a falcon tube to function as a collector. Methanol is separated from wine by microdistillation at 90°C in water bath and converted to formaldehyde in the collector. The collector contains an acidic permanganate solution that converts methanol to formaldehyde. Formaldehyde was then quantified by use of chromotropic acid in concentrated sulfuric acid. Experimental variables were optimized by using central composite design (CCD). Method detection and quantification limits were 183 mg L−1 and 584 mg L−1, respectively. The percent relative standard deviation (RSD%) were between 6.4 and 7.9. Accuracies were between 89.6 % and 92.4 %. Concentrations of methanol in five alcoholic solutions were between 2.9×104 and 3.0×104, mg/L, v/v (ppm). Due to its simplicity and cost effectiveness, this method can be used for routine, real-time determination of methanol in alcoholic solutions.

Comparative Analysis of Pharmaceutical Persistence in Canadian Wastewater Treatment Plants Utilizing Molecularly Imprinted Polymers and Commercial Solid Phase Extraction Sorbents

In this study, the performances of a synthesized Molecularly Imprinted Polymer (MIP) and a commercial Solid Phase Extraction (SPE) cartridge were compared in terms of the removal efficiency and quantification of pharmaceutical compounds in wastewater samples. Concentration analysis of Emtricitabine, Tenofovir, Naproxen, Diclofenac, Ibuprofen, and Efavirenz was conducted in influent, primary effluent, secondary effluent, and post-chlorination water samples using liquid chromatography-UV detection. Regressions analysis revealed high linearity (R2 values from 0.9980 to 0.9999) for the compounds, alongside recoveries ranging from 90.9% to 100%. The method detection limits (MDLs) were also determined. Removal efficiencies were computed, with Naproxen and Ibuprofen demonstrating complete removal (100%), while other compounds displayed different of removal efficiency levels. The MIP was found to perform slightly better than traditional SPE cartridges in terms of selectivity, efficiency, and overall performance. This study provides valuable insights into the concentrations of target compounds at various treatment stages, emphasizing the importance of choosing extraction cartridges in wastewater treatment processes.

Method Development and Validation of Luliconazole Bulk Drug Using Reverse Phase - HPLC Technique

Objective: To develop and validate the RP- HPLC method for determining Luliconazole in bulk and pharmaceutical formulations. Methods: Following the International Conference on Harmonization (ICH) guidelines, a sensitive, accurate, and specific reversed-phase HPLC technique was created and validated for the detection of Luliconazole. Using high-performance liquid chromatography, this drug was examined. A better separation of the drug was achieved by using Agilent Eclipse XDB C (4.6mm x 250mm, 5µm) with a mobile phase consisting of a mixture of Acetonitrile and Buffer in HPLC water. The ratio of 30:70 v/v (Formic acid and Acetonitrile) at a flow rate of 1.0 ml/ min and the detection was at the wavelength 295 nm using a Photodiode Arrays Detector. The planned method was able to produce good quality separation of the drug and its degradation products with sharp peaks. Findings: Luliconazole had a retention time of 2.38 ± 0.127 minutes. The technique was linear in the range of 10-100 µg/ml, with a correlation (r2) of 0.9995 and a run duration of 4 minutes. The method limit of detection (LOD) and limit of quantification (LOQ) were set at 0.1 and 1 g/ml, respectively. The method accuracy and system precision were estimated, and the findings were calculated as percentage RSD values, which were found to be limitations. Luliconazole recovery was 100% confirming the method's efficiency. Novelty: The presented approach was innovative and successfully fulfilled all validation requirements, including linearity, robustness, accuracy, reduced retention, and run time. This suggests that the method is appropriate for identifying the stability of luliconazole in bulk and pharmaceutical formulations. Keywords: RP-HPLC, Transferosome, ICH guidelines, Validation, Luliconazole

Current status of diagnosis and treatment and progress in drug research and development for hepatitis D

Chronic hepatitis D is a kind of severe viral hepatitis caused by co-infection with hepatitis D virus (HDV) and hepatitis B virus (HBV) or infection with HDV on the ground of HBV infection. Patients with hepatitis D who are infected with HBV often have faster disease progression and a worse prognosis. However, the public and clinicians have always paid little attention to chronic hepatitis D. Coupled with the limitations of detection methods and the absence of a screening system, the HDV screening rate in various regions of the world is at a low level. Consequently, the enthusiasm for screening, diagnosis, and treatment has been further reduced by the inadequate effectiveness of previous treatment methods. In recent years, progress has been made in the research and development of anti-HDV drugs, and a variety of drugs have already entered the clinical trial stage, and some have already been approved for commercialization in specific parts of the world. In this context, the world is also actively exploring effective ways to increase the HDV screening rate. The reflex test model can effectively raise the HDV screening rate and serve as a reference for HDV screening in other countries and regions, as demonstrated by studies conducted in the United Kingdom, France, and Spain, among others. This article will review the detection methods, screening, diagnosis, and treatment current status, as well as the progress in drug research and development, in order to help clinical physicians understand chronic HDV diagnosis and treatment.

Accurate and stable detection of p-phenylenediamine antioxidants and their transformation products in aquatic products using antioxidant protection – Analysis of actual aquatic products

Given the high toxicity of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) derivatives, such as 6PPD quinone (6PPDQ) to salmon, as well as their ubiquitous presence in the environment, the contaminant of aquatic food products has drawn significant attention. However, analytical methods for p-Phenylenediamines (PPDs) and their transformation products (TPs) in aquatic products remain underdeveloped. In particular, the degradation of some compounds and strong matrix effects complicate detection. In this study, we present a stable, rapid, and sensitive method combining salt-out assisted extraction, antioxidant protection, and multi-plug filtration clean-up (m-PFC) to detect two PPDs and five TPs in aquatic products. Crucially, the appropriate selection of antioxidants prevented the degradation of the easily oxidized target compounds. Further, the m-PFC method significantly enhanced the purification efficiency, achieving satisfactory recoveries (62.1–115 %), and method detection limits (MDLs) ranging from 0.00300 to 0.400 μg/kg. Subsequently, the method was applied to monitor PPDs and their TPs in aquatic products systematically, revealing the presence of 6PPD and N-isopropyl-N′-phenyl-1,4-phenylenediamine (IPPD) in white shrimp from aquafarms, whereas none of the seven target analytes were detected in fish and crab samples. These findings contribute to the detection of PPDs, their TPs and other unstable chemicals in aquatic products, thereby providing insights into their concentrations in these products.

Bioaccumulation potentials of per-and polyfluoroalkyl substances (PFAS) in recreational fisheries: Occurrence, health risk assessment and oxidative stress biomarkers in coastal Biscayne Bay

Per-and polyfluoroalkyl substances (PFAS) are a group of synthetic, highly fluorinated, and emerging chemicals that are reported to be used for both industrial and domestic applications. Several PFAS have demonstrated persistent, bioaccumulative and toxic tendencies in marine organisms. Therefore, this research aims to characterize and quantify these compounds in both recreational fisheries and surface water samples, including estimating their bioaccumulation potentials. In addition, we assessed the potential contribution of biomonitoring tools such as oxidative stressors and morphological index on fish and ecological health. Finally, human health risk assessment was performed based on available toxicological data on limited PFAS. All PFAS were detected in at least one sample except for N-EtFOSAA in lobster which was below the method detection limit. ƩPFAS body burden ranged from 0.15 to 3.40 ng/g wet weight (ww) in blackfin tuna samples and 0.37–5.15 ng/g ww in lobster samples, respectively. Wilcoxon rank paired test (α = 0.05) shows that there is statistical significance (ρ < 0.05) of ƩPFAS between species. Bioaccumulation factors (BAF) suggest an increasing trend in PFAS classes (PFCAs < PFSAs < FTSs), with higher BAFs observed in tuna compared to lobster. Long-chain PFESAs and FASAA were reported at higher concentrations in lobster compared to Blackfin tuna due to their bioavailability through sediment-sorption interactions. Although Fulton’s condition factor (FCF) indicates healthy fish conditions, oxidative stress biomarkers suggest that tuna and lobster might be under stress, which can weaken their immune system against exposure to emerging contaminants such as PFAS. Hazard risk (HR) suggests a low risk to human health based on the consumption of the studied species; however, the risk of contaminant exposure may be higher than estimated. This study is aimed at improving food safety by providing better understanding of how PFAS infiltrate into human diet and incorporating data on influence of contaminant exposure and environmental stressors on marine health.

4D-printed shape-programmable [H+]-responsive needles for determination of urea

Four-dimensional printing (4DP) technologies are revolutionizing the fabrication, functionality, and applicability of stimuli-responsive analytical devices. More practically, 4DP technologies are effective in fabricating devices with complex geometric designs and functions, and the degree of shape programming of 4D-printed stimuli-responsive devices can be optimized to become a reliable analytical strategy. Although shape-programming modes play a critical role in determining the analytical characteristics of 4D-printed stimuli-responsive sensing devices, the effect of shape-programming modes on the analytical performance of 4D-printed stimuli-responsive devices remains an unexplored subject. We employed digital light processing three-dimensional printing (3DP) with acrylate-based photocurable resins and 2-carboxyethyl acrylate (CEA)-incorporated photocurable resins for 4DP of the bending, helixing, and twisting needles. Upon immersion in samples with pH values above the pKa of CEA, the electrostatic repulsion among the dissociated carboxyl groups of polyCEA caused swelling of the CEA-incorporated part and [H+]-dependent shape programming. When coupling with the derivatization reaction of the urease-mediated hydrolysis of urea, the decline in [H+] induced shape programming of the needles, offering reliable determination of urea based on the shape-programming angles. After optimizing the experimental conditions, the helixing needles provided the best analytical performance, with the method's detection limit of 0.9 μM. The reliability of this analytical method was validated by determining urea in samples of human urine and sweat, fetal bovine serum, and rat plasma with spike analyses and comparing these results with those obtained from a commercial assay kit. Our demonstration and analytical results suggest the importance of optimizing the shape-programming modes to improve the analytical performance of 4D-printed stimuli-responsive shape-programming sensing devices and emphasize the benefits and applicability of 4DP technologies in advancing the development and fabrication of stimuli-responsive sensing devices for chemical sensing and quantitative chemical analyses.

Determining personal exposure to high production volume chemicals (HPVCs) and polycyclic aromatic hydrocarbons (PAHs) with silicone wristbands: A pilot study

High production volume chemicals (HPVCs) and polycyclic aromatic hydrocarbons (PAHs) are semi-volatile organic compounds (semi-VOCs) of great environmental concern because of their presence worldwide and health problems resulting from long-term exposure to some of them. It is essential to have robust analytical methods to monitor the concentrations of these compounds not only in environmental samples but also individual exposure. In this pilot study we develop and validate a multiresidue analytical method based on ultrasound-assisted extraction and gas-chromatography mass spectrometry for the simultaneous determination of 56 semi-VOCs using silicone wristbands (SWBs) as personal passive samplers. The developed method provided recoveries between 43% and 114% on sampled SWBs and method detection and quantification limits in the range of 0.1–35 ng/g and 0.3–119 ng/g, respectively. A preliminary study was performed with a small group of adults living in the industrial city of Tarragona (north-eastern Spain) to evaluate the applicability of SWBs for monitoring individual exposure to the studied HPVCs and PAHs. Benzothiazoles, benzenesulfonamides, UV stabilisers and phenolic antioxidants were determined for the first time in SWBs. Phthalates (PAEs), stood out above the rest, accounting for 52% of the total concentrations. Diethylhexyl phthalate was the compound found at the highest concentrations with values between 1.1 and 82 μg/g. Carcinogenic and non-carcinogenic dermal risk assessment was performed for adults and considering two scenarios (low and high). PAHs were the compounds with the highest carcinogenic and non-carcinogenic dermal risk regardless of the exposure scenario. The second family of compounds that contributed the most to the total risk were PAEs but high punctual concentrations of these compounds caused significant differences between exposure scenarios.

Implementation of gas chromatography tandem mass spectrometry for the analysis of six high boiling point polyhydric alcohols in cosmetics and toothpaste based on precolumn derivatization

Based on precolumn derivatization, an analytical method has been developed for the determination of six high boiling point polyhydric alcohols (HBPAs, b.p. > 300 ℃) in cosmetics and toothpaste, including erythritol, xylitol, Pro-Xylane-S, inositol, mannitol, and sorbitol. The water dispersion and oil in water samples were extracted by distilled water. The water in oil sample was firstly pre-dispersed with acetone, and then extracted by distilled water. The extract was concentrated to dry under nitrogen, and derivatized with acetic anhydride under the dispersion and catalysis of anhydrous pyridine. The derivatives were detected by gas chromatography-tandem mass spectrometry in the selected reaction monitoring mode, and quantified using arabinitol as internal standard. The experimental conditions such as the selection of columns, extraction procedures, and derivative conditions were optimized. This method was properly validated under the optimized conditions, and obtained excellent analytical features. Specifically, the correlation coefficients in the range of 0.02 ∼ 0.5 mg/L all exceed 0.992. The method limits of detection and quantification were 0.25 and 0.8 mg/kg, respectively. The average recoveries in toothpaste, cosmetics with oil in water and water in oil were 81.8 ∼ 107.1 %, with the relative standard deviation were 3.1 ∼ 7.2 %. The established method was successfully applied to commercial samples of different matrices, showing the advantages of simplicity, sensitivity, and good reproducibility, and can be used for the determination of HBPAs in cosmetics and toothpaste. The proposed methodology solves the problem that there is no detection method for HBPAs in cosmetics.

Multielement electrochemical vapor generation system coupled with atomic fluorescence spectrometer for simultaneous measurement of trace levels of As and Hg in coastal seawater samples

BackgroundToxic elements As and Hg in coastal waters affect human health through the food chain even at trace levels. The simultaneous determination of As and Hg in seawater using electrochemical vapor generation (ECVG) with atomic fluorescence spectrometer (AFS) currently has technical bottlenecks. One is the need for a simple and efficient chemical reaction cell and corresponding parameters to generate both AsH3 and Hg vapors, and the other is a suitable preservation method of the mixed standard solutions. ResultsA novel, efficient, online ECVG device was developed and interfaced with a laboratory-built multichannel AFS. The electrolytic cell adopted Sn–Pb alloy as the cathode material to generate both AsH3 and Hg vapors by electrolysis, replacing the unstable reagent tetrahydroborate (THB) usually used in most traditional vapor generation methods. The AFS was equipped with a built-in H2 generator for fuel supply, instead of the conventional acid-THB system. A mixed standard solution of As and Hg was prepared and preserved using thiourea-ascorbic acid as a fixing agent for Hg and a prereduction agent for As(V). The method detection limits (LOD, 3σ) were 0.005 and 0.003 μg/L for As and Hg, respectively. The relative standard deviations (RSD, n = 8) of the spiked samples were 2.8 % (0.50 μg/L As) and 3.1 % (0.05 μg/L Hg), respectively. The recoveries of standard spiked seawater samples with different salinities ranged from 86.1 % to 115.3 %. SignificanceThe system has been successfully applied to the simultaneous analysis of As and Hg in the seawater samples collected from the Xiamen coastal area. The study results provide a sensitive, accurate, and efficient method to promote the development and utilization of simultaneous analysis of multielement in seawaters.