Spike Recovery Research Articles

PolyCitrulline Modified Glassy Carbon Electrode as a Voltammetric Sensor for the Simultaneous Determination of Metabolic Syndrome Biomarkers-Uric Acid and Tyramine

This article describes the development of a simple and sensitive voltammetric sensor for the simultaneous determination of Uric acid (UA) and Tyramine (TYM), which act as metabolic syndrome (Mts) biomarkers. The electropolymer of the naturally occurring amino acid citrulline (Cit) has been employed as the electrode modifier in this sensor. Glassy carbon electrode modified with poly citrulline has been characterized with the aid of techniques such as scanning electron microscopy (SEM) and SEM-energy dispersive X-ray analysis, surface area calculations and electrochemical impedance spectroscopy. Studies were carried out to optimize parameters like the cycles of polymerisation, supporting electrolyte and its pH. The sensor which offers fast determination of the analytes using square wave voltammetry possesses a limit of detection 1.32 × 10−8 M and 4.20 × 10−8 M for UA and TYM, respectively. The applicability of the sensor in body fluids has been proved through spike recovery analysis in artificial blood serum and urine samples. Interference on the voltammetric signals created by some dominant coexisting species of the analytes was found to be tolerable.

Ethylendiaminetetrakis(1,10-phenanthroline)dicopper(II) chlorided: Synthesis and application for voltammetric determination of doxycycline in real samples

The study describes on the preparation of a new homobinuclear mixed ligand complex µ-ethylendiaminetetrakis(1,10-phenanthroline)dicopper(II) chloridedihydrate (EP4Cu2CH2) from a previously reported complex chlorobis(1,10-phenanthroline)copper(II) chloridemonohydrate (CP2CuCH). The synthesis was checked by spectroscopy (UV–Vis, FT IR), CHN elemental analysis, Cu determination using ICP-OES, electrolytic conductivity, qualitative and quantitative chloride estimation, and melting point measurements. The new complex was applied for the modification of a glassy carbon electrode (poly(EP4Cu2CH2)/GCE) for determination of doxycycline (Doxy), (which belongs to a tetracycline antibiotic, mainly used for the treatment of a wide bacterial infections) by selective, accurate, and precise differential pulse voltammetric method. Electrode characterization revealed modification of the electrode surface by a conductive, and electroactive polymer film (poly(EP4Cu2CH2)/GCE) leading to improved effective electrode surface area. In contrast to the bare electrode, the appearance of two well-resolved irreversible oxidative peaks at much reduced potential with sevenfold current enhancement at poly(EP4Cu2CH2)/GCE showed the catalytic effect of the modifier towards Doxy. Differential pulse voltammetric current response of poly(EP4Cu2CH2)/GCE showed a linear dependence on the concentration of Doxy in the range 5 × 10−8 – 3.5 × 10−4 M with a detection limit of 3.5 × 10−9. The Doxy levels in four tablet brands were in the range 96.00–101.30 % of their labeled values. Spike recovery results in tablet, cow milk, and human urine samples were 98.90–100.73 %, 98.30–100.00 %, and 98.50–100.54 %, respectively. Based on the innovative mixed ligand poly(EP4Cu2CH2)/GCE, the interference recovery results about 4.79 % error, lesser LoD, and a broader concentrationrange than most previously published methods validated the present method’s potential applicability with excellent accuracy and sensitivity for Doxy determination in various real samples with complex matrix.

Solid-Phase Microextraction Mediated Solid-Phase Dielectric Barrier Discharge Vapor Generation-Atomic Fluorescence Spectrometry for Sensitive Determination of Mercury in Seawater.

A novel method coupling solid-phase microextraction (SPME) to solid-phase dielectric barrier discharge (SPDBD) vapor generation was proposed and used for the sensitive detection of trace mercury (Hg) in seawater with atomic fluorescence spectrometry (AFS) in this work. The method proposed herein offers the unique advantages of integrating desorption and chemical vapor generation into one step, eliminating the use of elution reagents, and reducing the analysis time. SPME with multiwalled carbon nanotubes (MWCNTs) coated on the glass tube was used to extract Hg2+ in seawater. The Hg2+ was then desorbed and reduced to Hg0 vapor by SPDBD, which was detected by cold vapor AFS. The parameters affecting Hg2+ extraction, desorption, and vapor generation were studied. The detection limit of Hg2+ was 0.0003 μg L-1, and the relative standard deviation at a Hg2+ concentration of 0.05 μg L-1 was 4.4%. This method also has excellent antimatrix interference ability for Hg2+ determination with recoveries between 91.8% and 101.1% in the presence of extremely high concentrations (two million times excess) of coexisting ions. The practicality of this method was also evaluated by analyzing two different certified reference materials of Hg2+ in water and several seawater samples with good spike recoveries (94.0%-107.4%). Compared with solid-phase photothermo-induced vapor generation, this method has higher extraction efficiency and higher desorption efficiency without the assistance of heating as well as a lower detection limit of Hg2+, which is capable of performing trace Hg analysis in seawater.

Simultaneous Determination of Sulfamethoxazole and Trimethoprim from Clinical Urine and Blood Serum Samples by the Application of Poly(Cu2P4BCL4)/GCE.

Synthetic antibiotics known as sulfonamides suppress the synthesis of tetrahydrofolic acid, which cures respiratory tract infections and protozoal infections by preventing the creation of dihydrofolic acid. Electrochemical sensors based on tetrakis(1,10-phenanthroline)-μ-(4,4'-bipyridine) dicopper(II) chloride monohydrate ([P2Cu-Bip-CuP2]Cl4·H2O or simply Cu2P4BCl4) have been successfully applied for the determination of sulfamethoxazole (SMX) and trimethoprim (TMP) from samples. The experimental conditions and parameters were optimized to achieve the best electrode performances for simultaneous quantification of SMX and TMP. Based on the analysis of the effect of scan rate on the peak parameters, the R 2 for the peak current vs square root of the scan rate was greater than that of the peak current vs scan rate, indicating diffusion-controlled behavior of both species. The current intensities of both SMX and TMP were highly improved due to surface activation of the electrodes by electropolymerization. For SMX, the limit of detection was determined to be 27.94 nM, while for TMP, it was 21.56 nM, and the limit of quantifications was 71.88 nM, and the corresponding relative standard deviation for each was 0.74% and 0.11%. The constructed electrode was stored for varying durations ranging from two h to 2 days, and it was found to be above 97% stable after storing for 15 days. The real applicability of the suggested sensor for the simultaneous determination of SMX and TMP was verified by sensing clinical serum and urine samples and their spike recovery studies.

Novel electrochemical sensor based on poly([Cu(H2O)2P2]I2)/GCE for the determination of trimethoprim in clinical samples and cow's milk samples

A Novel bioanalytical detector based on Poly(Diaquabis(1,10-phenanthroline copper (II) Iodide) (poly([Cu(H2O)2P2]I2)/GCE) has been fabricated by potentiodynamic polymerization of [Cu(H2O)2P2]I2. The synthesized complex and the fabricated electrodes showed a promising electrocatalytic behavior towards the electrooxidation of Trimethoprim (TPM). Based on the regression coefficient value of scan rate with peak current and square root of peak current, the oxidation of TMP at poly([Cu(H2O)2P2]I2)/GCE was dominated by diffusion. Under the optimized experimental conditions and square wave voltammetric parameters, the poly([Cu(H2O)2P2]I2)/GCE revealed very wide responses in the range of concentration of 500 nM–160 μM with a limit of detection of 3.91 nM and a Limit of quantification of 13.02 nM with the relative standard deviation below 1.75 %. The valuable applicability of the fabricated sensor for the determination of TMP in real samples, including cow's milk, blood serum, and human urine, was successfully investigated. The electroanalysis results from the spike recovery and interference study provided an excellent range of recovery with an error percent of below 3.0 % in the combination effect with the potential interferents. The sensor exhibited excellent reproducibility, sensitivity, long-term stability, high accuracy, and fast response. The developed bioanalytical sensor revealed the best application prospect for biomedicine and environmental monitoring activities.

Automatic immunomagnetic beads cleanup and isotope dilution-based liquid chromatography tandem mass spectrometry for the determination of aflatoxins in feed and feedstuff

In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method based on immunomagnetic bead cleanup and isotope dilution was established for the simultaneous detection of four aflatoxins (aflatoxins B1, B2, G1, and G2) in feed and feedstuff. The samples were extracted with an acetonitrile–water mixture (84 + 16, v/v), purified using automatic immunomagnetic beads, and detected by LC-MS/MS. Under the optimal LC-MS/MS conditions, the four mycotoxins had a linear relationship in the concentration range of 0.5–50 µg/kg, and the correlation coefficients were all greater than 0.99. The limits of detection of the four aflatoxins ranged from 0.075–0.17 µg/kg, and the limits of quantification ranged from 0.25–0.5 µg/kg. The average spike recoveries of the four common feed and feedstuff matrices (corn, soybean meal, pig compound feed, and chicken compound feed) at three spiked levels (2, 10, and 50 µg/kg) ranged from 80.8–118.3 %, and the relative standard deviations (RSDs) were all less than 7.80 %. Thirty-two actual feed samples were analyzed for the four aflatoxins. Aflatoxin B1 was detected in nineteen samples (0.11–6.39 µg/kg); aflatoxin B2 was detected in four samples (0.12–0.43 µg/kg); aflatoxin G1 was detected in four samples (0.19–0.57 µg/kg), and aflatoxin G2 was not detected. The immunomagnetic beads cleanup system could automatically remove each of the four aflatoxins in feed and feedstuff and realize batch sample processing in 20 min. The established LC-MS/MS method has high accuracy and repeatability, and it can be used for the rapid and simultaneous determination of four aflatoxins in feed samples.

Enhancing Pregnancy Care: Harnessing Label‐Free Immunosensors for Pre‐Eclampsia Detection Using PdNPs/Poly(3,5‐Diaminobenzoic Acid) Modified Glassy Carbon Electrodes

AbstractPlacental Growth factor (PlGF) is one of the biomarkers useful for detecting pregnancy hypertension disorder, Pre‐eclampsia. Herein, we focus on developing a label‐free immunosensor using simple electrochemical methods to detect PlGF antigens for pre‐eclampsia diagnosis. The work includes the electrochemical deposition of Palladium nanoparticles (PdNPs) on the glassy carbon electrode (GCE) surface using amperometry followed by electropolymerization of diaminobenzoic acid (DABA) onto the PdNPs/GCE. Antibody (aPlGF) was covalently immobilized on the pDABA/PdNPs/GCE using EDC/NHS reaction. The interaction of the antibody with the antigen was measured using differential pulse voltammetric technique. The linear range obtained for the immunosensor is 1–25 ng mL−1 with a limit of detection of 53 pg mL−1. The stability and reproducibility of the sensor were obtained in the acceptable range. The developed sensor was used to detect PlGF antigen in artificial blood and urine samples by spike recovery analysis.

Fill, Fold, Photo: Preconcentration and Multiplex Detection of Trace Level Heavy Metals in Water.

Heavy metal contamination is an increasing global threat to human and environmental health, particularly in resource-limited areas. Traditional platforms for heavy metal detection are labor intensive and expensive and require lab facilities. While paper-based colorimetric sensors offer a simpler approach, their sensitivity limitations prevent them from meeting legislative requirements for many metals. Existing preconcentration systems, on the other hand, can achieve lower detection limits but typically focus on analyzing only one metal, making comprehensive monitoring difficult. We address these limitations by introducing a low-cost preconcentration system coupled with colorimetric analysis for the simultaneous detection of seven metal ions at low ppb levels without the need for external equipment outside a smartphone. The system achieved detection limits of 15 ppb (Ni(II)), 7 ppb (Cu(II)), 2 ppb (Fe(III)), 20 ppb (Cr(VI)), 13 ppb (Pb(II)), 26 ppb (Hg(II)), and 15 ppb (Mn(II)) with six out of seven limits of detection values falling well below EPA regulatory guidelines for drinking water. The user-friendly Fill, Fold, Photo approach eliminates complex pretreatment steps. Smartphone-based detection offers portable quantification within seconds. Employing masking strategies ensured higher selectivity for each assay on the card, while our packaging protocols enable system stability for over 4 weeks of study, facilitating mass production and deployment within a realistic time frame. To validate the sensor's performance in real-world scenarios, the sensor was tested with environmental water samples. The sensor demonstrated good recovery, ranging from 77% to 94% compared to the standard ICP-MS method. Furthermore, spike recovery analysis confirmed the sensor's accuracy, with a relative standard deviation (RSD) of less than 15%. This technology holds significant promise for future development as a convenient, portable solution for field-based monitoring of a broad spectrum of water contaminants, including pesticides, PFAS, fertilizers, and beyond.

Lab-on-a-chip paper-based electrochemically assisted solid-phase microextraction and ion selective sensor for determination of naproxen in biological fluid samples

BackgroundThe integration of paper-based analytical devices with lab-on-a-chip technology has opened up new possibilities for miniaturized, rapid, low cost and portable diagnostic testing in resource limited settings. This work introduces an integrated lab-on-a-chip platform coupling paper-based analytical devices (LOC-PADs) for dual usage: electrochemically controlled solid-phase microextraction (EC-SPME) and determination of naproxen (NAP) by potentiometric ion-selective electrode (ISE) in biological samples. ResultsConductive papers were successfully fabricated by a chemical procedure. Thereupon, a conducting molecularly imprinted polymer (CMIP) film based on PPy and an anionic model drug (NAP) as a template were applied to the conductive paper substrate via electrochemical methods. A microfluidic chip device was employed to assess the analytical performance of the fabricated paper-based CMIP. The designed chip is divided into two parts with a microfluidic channel between them. The first chamber is an extraction zone for EC-SPME of NAP by using the CMIP paper as a selective sorbent. The second chamber is the detection zone and consists of a paper-based NAP ion selective sensor for potentiometric detection of drug. The analytical process was investigated and optimized for each chamber. Remarkable selectivity towards NAP was achieved in the concentration range from 4.0 × 10−7 to 1.0 × 10−2 mol L−1 with determination coefficient (R2 = 0.99) and the limit of detection (LOD) was 2.0 × 10−7 mol L−1. Anionic Nernstian compliance was gained −58.5 ± 0.5 mV decade−1, and response time in the detection step was 7s for ISE. Satisfactory spiking recovery values within the acceptable range of 90–110 % with RSDs ≤7 % were achieved for the analysis of real samples with fully portable LOC device. SignificanceThe LOC-PADs were favorably used for selective extraction and determination of NAP in serum and saliva samples, respectively. EC-SPME caused sample clean-up, reduced or eliminated different interferences and enhanced selective response of ISE as detection zone of device. Integration of EC-SPME and ISE in a single chip enabled easy and fast determination of trace amounts of NAP in limited real sample volumes, and fully portable advantages.

Enhanced chemiluminescence by carbon dots for rapid detection of bisphenol A and nitrite

Herein, a novel chemiluminescence (CL) sensor was successfully developed based on chlorine doped carbon dots (Cl/CDs) for the rapid determination of bisphenol A (BPA) and nitrite. The Cl/CDs were synthesized through a hydrothermal method, using ascorbic acid as the precursor and hydrochloric acid as the dopant. It was found that Cl/CDs significantly enhanced the CL intensity of the acid-KMnO4 system, while BPA and nitrite quenched the CL intensity of the Cl/CDs-sensitized acid-KMnO4 system. Under optimal conditions, BPA exhibited a linear detection range of 0.05–10 μM, with limits of detection (LOD) and quantification (LOQ) of 0.86 nM and 2.8 nM, respectively. Nitrite showed a linear detection range of 0.7–100 μM, with LOD and LOQ of 22.5 nM and 75 nM, respectively. The CL sensor was successfully use to determine BPA in water samples and nitrite in pickles, ham and celery, with spike recovery rates of 96.3 %–104.8 % and 96.0 %–104.9 %, respectively.

Determination of 4-n-butylresorcinol by fluorescence derivatization based on dopamine

4-n-butylresorcinol (4nBR) is a frequently utilized as whitening ingredients in skincare cosmetics. Compared with other whitening ingredients, it can effectively inhibit tyrosinase with lower toxicity and superior inhibition efficacy. Under alkaline conditions, an induced oxidative coupling reaction can occur between 4nBR and dopamine (DA) to generate strong fluorescent substance azamonardine with an intense emission band centering at 476 nm when excited at 440 nm. This phenomenon can be used to establish a fluorescence analysis method for 4nBR. The results indicated that the linear range of the method was 1.0–24.0 nmol L−1, and the detection limit was as low as 0.25 nmol L−1. The method showed high sensitivity, good selectivity, mild experimental conditions and low cost. The proposed method was successfully used to detect 4nBR in cosmetics, and the results were consistent with those of HPLC. The spiking recoveries were between 98.2% and 108 %.

Location and function of TDP-43 in platelets, alterations in neurodegenerative diseases and arising considerations for current plasma biobank protocols

The TAR DNA Binding Protein 43 (TDP-43) has been implicated in the pathogenesis of human neurodegenerative diseases and exhibits hallmark neuropathology in amyotrophic lateral sclerosis (ALS). Here, we explore its tractability as a plasma biomarker of disease and describe its localization and possible functions in the cytosol of platelets. Novel TDP-43 immunoassays were developed on three different technical platforms and qualified for specificity, signal-to-noise ratio, detection range, variation, spike recovery and dilution linearity in human plasma samples. Surprisingly, implementation of these assays demonstrated that biobank-archived plasma samples yielded considerable heterogeneity in TDP-43 levels. Importantly, subsequent investigation attributed these differences to variable platelet recovery. Fractionations of fresh blood revealed that ≥ 95% of the TDP-43 in platelet-containing plasma was compartmentalized within the platelet cytosol. We reasoned that this highly concentrated source of TDP-43 comprised an interesting substrate for biochemical analyses. Additional characterization of platelets revealed the presence of the disease-associated phosphoserine 409/410 TDP-43 proteoform and many neuron- and astrocyte-expressed TDP-43 mRNA targets. Considering these striking similarities, we propose that TDP-43 may serve analogous functional roles in platelets and synapses, and that the study of platelet TDP-43 might provide a window into disease-related TDP-43 dyshomeostasis in the central nervous system.

Evaluation of a Chemiluminescent Enzyme Immunoassay for the Detection of Prostaglandin E-Major Urinary Metabolite (PGE-MUM).

We developed a fully automated quantitative immunoassay for the detection of prostaglandin E-major urinary metabolite (PGE-MUM). In this study, we evaluated the analytical performance of this assay. Sensitivity, within-run reproducibility, correlation with radioimmunoassay (RIA), cross-reactivity, dilution linearity, spike recovery performance, analyte stability, and effects of coexisting substances were evaluated. The assay was also used to measure PGE-MUM in 211 healthy people. The limit of detection and quantification were 1.0 and 1.3 ng/mL, respectively. When the assay was performed six times in a single run, the coefficient of variation ranged from 1.4% to 2.2%. The coefficient of correlation with a preceding RIA method was 0.970 with a correlation slope of 0.88. There was no cross-reactivity with PGE-MUM analogs. Linearity of dilution was confirmed at up to 16-fold dilution with assay results within 100 ± 20% of the theoretical values calculated based on the undiluted sample. Spike recovery was good and ranged from 94% to 101%. Analyte stability was tested by storing samples at 25°C for 6 days, 10°C for 1 month, and by performing up to five freeze-thaw cycles. Assay results were all within 100 ± 10%, the values measured before storage and before the freeze-thaw process. Assay results in healthy people ranged from 3.1 to 162.7 ng/mL (mean: 35.8 ng/mL). After correction for creatinine, the 95% confidence interval was 8.68-42.25 μg/g creatinine. The assay precisely detects PGE-MUM.

Systematic evaluation supports the use of ELISA for quantification of calprotectin in equine feces, a first step toward noninvasive quantification of intestinal inflammation in horses.

To optimize and evaluate methods for the detection of the inflammatory biomarkers myeloperoxidase (MPO) and calprotectin (CP) in equine feces by ELISA. Healthy horses (n = 28) and horses with intestinal inflammation (n = 10). Feces were suspended in buffer to create fecal supernatant. Serum and fecal supernatant were analyzed using ELISA kits validated for the detection of MPO and CP in equine serum. Assay validation steps included intra- and interassay variability (coefficient of variation [CV]), dilution linearity, spike recovery, and sample type correlation. Variations in sample handling protocols (centrifugation speed, extraction buffer, and filtration) were evaluated. 17 paired fecal and serum samples were used for initial analysis (10 healthy horses, 7 colitis). Previously reported sample handling protocols resulted in detectable MPO and CP but poor CV, linearity, and spike recovery. There was a linear correlation between serum and fecal samples for CP but not MPO. There was a significant difference between the concentration and CV of alternative sample handling protocols for CP and MPO, with improved CV for CP (2.1% to 18.6%) but not MPO (14.4% to 53.4%). Processing fresh feces with a fecal extraction buffer and filtration of supernatant resulted in the best CV (0.5% to 3.8%) and recovery (45% to 64%) for CP. Detection of MPO was inconsistent regardless of method. There are few reliable diagnostic modalities for inflammation of the equine large colon. Findings support quantification of CP in equine feces using the described ELISA kit and protocol. With additional study to establish reference interval and clinical utility, the fecal inflammatory biomarker CP may allow for noninvasive quantification of intestinal inflammation in horses.

Development of a Multiplexed Sphingolipids Method for Diagnosis of Inborn Errors of Ceramide Metabolism.

Sphingolipids play a crucial role in cellular functions and are essential components of cell membranes, signaling molecules, and lipid metabolism. In particular, ceramide is a key intermediate in sphingolipid metabolism and defects in ceramide metabolism can lead to various inborn errors of metabolism, making ceramides important targets for clinical screening and diagnosis. Detecting altered concentration patterns of sphingolipids is desirable for distinguishing related inborn errors of metabolism for diagnosis and treatment monitoring. We developed a liquid chromatography-tandem mass spectrometry method with a pathway-oriented approach to focus on sphingolipids involved in ceramide metabolism. A total of 47 sphingolipids bearing different head groups and side chains were targeted. Precision/reproducibility, linearity, and spike recovery extraction efficiency tests were performed on plasma and serum samples from confirmed cases of sphingolipidosis. Linearity of the method showed the coefficient of determination (r2) for all standards to be >0.99 with a slope of 1.00 ± 0.01. Intra- and interday reproducibility of standards spiked into plasma and serum revealed a coefficient of variation <20%. Spike and recovery assessment showed recovery values of 80%-120% for all standards. Altered levels of sphingolipids from patients with hereditary sensory and autonomic neuropathy caused by pathogenic variants in SPTLC2 and hypomyelinating leukodystrophy related to variants in DEGS1 were detected, in agreement with trends reported in earlier studies confirming the utility of this pathway-centric method. This method can serve as a useful tool to simultaneously monitor sphingolipids, enabling screening and diagnosis of inborn errors of ceramide metabolism.

Determination of Taurine in Infant Formula and Adult/Pediatric Nutritionals by Ultra High-Performance Liquid Chromatography with Multiple Reaction Monitoring-Mass Spectrometry: Single-Laboratory Validation, First Action 2022.08.

Taurine (2-aminoethanesulfonic acid) is an essential β-amino acid, which is one of the most abundant intracellular amino acid component in humans. The level of free taurine in human milk is higher than in bovine milk. Since taurine is considered important for the development of a newborn, fortification of infant nutrition with taurine is common. This publication describes a rapid method for the determination of taurine in infant formula and adult/pediatric nutritionals. This publication demonstrates the suitability and applicability of the method to determine taurine content in infant formula and adult/pediatric nutritionals. Test portions are deproteinized by acid in an aqueous environment prior to analysis. The level of taurine is analyzed by hydrophilic interaction chromatography (HILIC) coupled with multiple reaction monitoring MS (MRM-MS). Quantitation is accomplished using a stable isotope-labeled internal standard (SILS) for taurine. The accuracy of the method was validated using standard reference materials and spike recovery studies. The average recoveries ranged between 92% and 105%. The relative standard deviation repeatability (RSDr) and relative standard deviation intermediate precision (RSDiR) were in the range of 0.7-4.6% (RSDr) and 1.3-6.7% (RSDiR). The limit of quantitation (LOQ) was below the requirement of 0.5 mg/100 g. The single-laboratory validation (SLV) of the method for determination of taurine content in infant formula and adult/pediatric nutritionals demonstrates that it meets the requirements per AOAC INTERNATIONAL Standard Method Performance Requirements (SMPR) 2014.013. A fast method to selectively determine the content of taurine in infant formula and adult/pediatric nutritionals was evaluated and found to be fit for purpose for routine product compliance testing. Based on the results of this SLV, the method was approved by the AOAC Stakeholder Program on Infant Formula and Adult Nutritionals (SPIFAN) Expert Review Panel for SPIFAN Nutrient Methods for First Action Official MethodsSM status.

Arsenic speciation analysis in human urine for long term epidemiological studies: The Multi-Ethnic Study of Atherosclerosis (MESA)

Arsenic is a ubiquitous toxic metalloid causing serious health problems. Speciation analysis of arsenic in human urine provides valuable insights for large-scale epidemiological studies and informs on sources of exposure as well as human metabolism. The Multi-Ethnic Study of Atherosclerosis (MESA) is a valuable cohort for assessing chronic low-moderate arsenic exposure and health effects in an ethnically diverse US population. We present a state-of-the-art arsenic speciation analysis methodology and its application to 7677 MESA spot urine samples based on high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry. This method is fast, robust and detects a total of 11 individual As species at method detection limits of 0.02–0.03 μg arsenic/L urine for each individual species. Our analytical approach features excellent mean method accuracy (98%) and precision (5%) for the main arsenic species in urine (arsenobetaine, methylarsonic acid, dimethylarsinic acid, and total inorganic As); intra- (3–6%) and inter-day coefficients of variability (5–6%); column recovery (96 ± 7%); and spike recovery (97 ± 6%). The main arsenic species were detectable in ≥95% of urine samples due to the implementation of an oxidation step. Each individual minor arsenic species was detectable in ≤25% of all urines, although at least one of them was detected in almost half the participants. We identified two minor urinary arsenic species as dimethylarsinoylacetic acid and dimethylarsinoylpropionic acid, potential metabolites of seafood-related arsenicals. We observed differences in individual As species excretion by race/ethnicity, with Asian-American participants featuring 3–4 times higher concentrations compared to other participants. We also found differences by site, body mass index, smoking status, rice intake, and water arsenic levels, potentially indicating different exposures or related to individual bio-metabolism. The proposed approach is suitable for epidemiological studies and the collected data will constitute the base for future research on potential health effects of chronic low-level arsenic exposure.

The Application of Hydrogen Sulfide Fluorescent Probe in Food Preservation, Detection and Evaluation.

This work primarily reviewed the response mechanism of fluorescent probes for H2S detection in foodstuffs in recent years, as well as the methodologies employed for detecting foodstuffs. Firstly, the significance of studying H2S gas as an important signaling molecule is introduced. Subsequently, a review of the response mechanism of the scientific community on how to detect H2S in foodstuffs samples by fluorescent probe technology is carried out. Secondly, the methods commonly used for detecting foodstuffs samples are discussed, including the test strip method and the spiking recovery methods. Nevertheless, despite the significant advancements in this field, there remain some research gaps. Finally, the article identifies the remaining issues that require further attention in current research and proposes avenues for future investigation. More importantly, this work identifies the current limitations of research in this field and proposes future applications of fluorescent probes for H2S in assessing food freshness and determining food spoilage. Therefore, this review will provide robust technical support for the protection of consumer health and the advancement of the sustainable development of the food industry and also put forward some new ideas and suggestions for future research.

Total arsenic and arsenic species in selected seafoods: Analysis using high-performance liquid chromatography- inductively coupled plasma mass spectrometry and health risk assessment

The objective of the present study was to determine the inorganic and organic arsenic species and assess the actual risk of selected seafood produced in Sri Lanka in terms of inorganic arsenic species. A total of 80 samples, comprising 75 seafood samples and 5 freshwater samples, including mollusks, echinoderms, and crustaceans, were analyzed for their total arsenic (TA) levels and arsenic species. TA levels in seafood were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after microwave digestion. Arsenic species, including arsenobetaine (AsB), arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA), were selectively separated and quantified using High-Performance Liquid Chromatography (HPLC) coupled to ICP-MS, following water bath extraction with 30 mmol/L nitric acid. The TA levels in seafood ranged from 0.036 to 11.686 mg kg-1. The spike recovery values for the five arsenic species lay within 80 % to 120 %, and the chromatographic recovery percentages ranged from 85.5 % to 123.6 %. In most samples, 100 % AsB was detected. Sea cucumber and both marine and freshwater giant river prawns showed AsB percentages of the total arsenicals at 83.2 %, 39.7 %, and 21.3 %, respectively. DMA was found in sea cucumber and marine giant river prawn at levels of 0.065 mg kg-1 and 0.048 mg kg-1, respectively, while MMA was not detected in any samples. AsIII was found in marine water giant river prawn and freshwater giant river prawn at levels of 0.010 mg kg-1 and 0.044 mg kg-1, respectively. AsV was only found in marine giant river prawn at a concentration of 0.193 mg kg-1. No other samples contained detectable levels of inorganic arsenicals. The Target Hazard Quotient (THQ) values for marine and freshwater giant river prawn were 0.90 and 0.2, respectively, indicating no significant health risks since the THQ values were <1. Therefore, our study suggests that consuming the studied seafood does not pose any health risks in terms of arsenic.

Green Approach for Simultaneous Quantitative Analysis of Fluoroquinolones in the Environment using Three-Dimensional Fluorescence Coupled with Second-Order Calibration Method.

In this study, a straightforward and quick analytical technique based on the self-weighted alternating trilinear decomposition (SWATLD) algorithm in conjunction with excitation-emission matrix (EEM) fluorescence for the simultaneous determination of the antibiotics levofloxacin (LVFX) and ciprofloxacin (CIP) in environmental waters and sediments was developed. This approach completely utilizes the "second-order advantage" and inherits the great sensitivity of classic fluorescence. It replaces or improves the conventional "physical/chemical separation" with "mathematical separation", enabling direct and quick quantification of the target analytes even in the presence of unknown interferences, greatly streamlining sample preparation procedures, consuming less solvent, and speeding up analysis time, and allows successful and environmentally friendly solution of overlapping fluorescence spectra of multiple components in complicated environmental matrices without cumbersome pretreatment steps and complex and expensive instrumentation. The limits of detection varied between 0.34 and 0.67 ng mL- 1, and the average spiking recoveries of LVFX and CIP in water and sediment ranged from 97.6 to 107.7% with relative standard deviations lower than 6.6%. The developed method shows the reliability of the technology and the ability to quickly detect trace antibiotics in lake water even in the presence of unidentified interferents.