Simultaneous Electrochemical Detection of Dopamine and Tryptophan Using 3D Goethite-Spongin Composites.

In this study, a facile approach for simultaneous determination of dopamine (DA) and tryptophan (TRP) using a 3D goethite-spongin-modified carbon paste electrode is reported. The prepared electrode exhibited excellent electrochemical catalytic activity towards DA and TRP oxidation. The electrochemical sensing of the modified electrode was investigated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Through differential pulse voltammetry analysis, two well-separated oxidation peaks were observed at 28 and 77 mV, corresponding to the oxidation of DA and TRP at the working electrode, with a large peak separation of up to 490 mV. DA and TRP were determined both individually and simultaneously in their dualistic mixture. As a result, the anodic peak currents and the concentrations of DA and TRP were found to exhibit linearity within the ranges of 4-246 µM for DA and 2 to 150 µM for TRP. The detection limits (S/N = 3) as low as 1.9 µM and 0.37 µM were achieved for DA and TRP, respectively. The proposed sensor was successfully applied to the simultaneous determination of DA and TRP in human urine samples with satisfactory recoveries (101% to 116%).

Development of a novel UPLC approach to co-prediction of four active compounds in a multi-component pharmaceutical preparation.

In this work, a new ultra-performance liquid chromatography method based on photodiode array detection (UPLC-PDA) was first developed for the quantitative analysis of the quaternary mixture of ascorbic acid (AA), paracetamol (PAR), caffeine (CAF) and chlorpheniramine maleate (CPA) in a commercial dosage form. The developed UPLC-PDA method offered a new possibility for the co-determination of four active ingredients in a drug combination with short run time and simple sample preparation. The successful chromatographic separation of the four drugs was performed using a Waters Acquity UPLC BEH C18 column (1.7 µm 2.1 × 100 mm) (Mildford, USA) and a mobile phase consisting of water (12 %), acetonitrile (13 %) and 0.1 M H3PO4 (75 %) at a flow rate of 0.25 mL/min. The validation of the proposed UPLC-PDA approach was verified by analyzing synthetic mixtures, inter- and intra-day experiments, and commercial powder samples and provided satisfactory results.

Polycarboxyl ionic liquid functionalized Yb-MOFs nanoballs based dual-wavelength responsive photoelectrochemical aptasensor for the simultaneous determination of AFB1 and OTA.

Developing an accurate and precise approach for the simultaneous detection of ochratoxin A (OTA) and aflatoxin B1 (AFB1) is significant for food safety surveillance. Herein, a photoelectrochemical sensing platform was constructed based on polycarboxylic ionic liquid functionalized metal-organic framework integrated with gold nanoparticles (Yb-MOFs@AuNPs). Sulfhydryl functionalized hairpin DNA (hDNA) was immobilized on a Yb-MOFs@AuNPs modified glassy carbon electrode (GCE) surface through Au-S bond. After blocking residual active binding sites with BSA, gold nanoparticles-labeled AFB1 aptamer (AuNPs-Apt 1) and gold nanorods-labeled OTA aptamer (AuNRs-Apt 2) were introduced to construct a photoelectrochemical aptasensor for the simultaneous determination of AFB1 and OTA. Due to the surface plasmon resonance effect and the nanometer size effect of gold nanomaterials, the photoelectrochemical aptasensor can output photocurrent responses as being excited with different wavelengths at 520 nm and 808 nm, respectively. When the AFB1 and OTA concentration in the range of 0.001-50.0 ng mL-1, a good linear relationship between the photocurrent difference (ΔI) before and after recognizing targets and the logarithm of AFB1 or OTA concentration was obtained. The detection limits for AFB1 and OTA were 0.40 pg mL-1 and 0.19 pg mL-1, respectively. AFB1 and OTA in corn samples were detected simultaneously by the photoelectrochemical aptasensor.

Simultaneous determination of 17 regulated and non-regulated Fusarium mycotoxins co-occurring in foodstuffs by UPLC-MS/MS with solid-phase extraction.

Fusarium species produce numerous mycotoxins known to co-occur in food. While some of these mycotoxins (e.g., deoxynivalenol, fumonisins) are regulated in several countries, others are non-regulated (e.g., nivalenol, beauvericin). In this study, UPLC-MS/MS with solid-phase extraction cleanup was used to determine 17 Fusarium mycotoxins (FTs) simultaneously. The method showed excellent performance in terms of linearity (R2 > 0.99), LOD (<1.2 µg/kg), LOQ (<3.6 µg/kg), accuracy (70.0-116.3 %), repeatability (<15.7 %), reproducibility (<25.3 %), and expanded uncertainty (<41.7 %). The validated method was successfully applied to 198 marketed food samples collected in South Korea. Of the tested samples, 79 % were contaminated with at least one FT. Job's tears showed the highest prevalence of 14 FTs, and sorghum had the highest total FTs level (3.03 mg/kg). The results suggest that this method can be used for the simultaneous analysis of 17 FTs in food samples, which would serve as crucial information for risk management.

A robust method for simultaneous determination of eight B vitamins in human serum by liquid chromatography tandem mass spectrometry.

The level of vitamin B group in human serum is an important index of human health. Among B vitamins, cyanocobalamin in serum is unstable and its content is extremely low. Rapid and simultaneous detection of multiple B vitamins including cyanocobalamin is a challenge. Herein, we have developed a rapid and stable method that can realize the determination of thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxic acid, biotin, 5-methyltetrahydrofolate, and cyanocobalamin simultaneously in 6 min. The method was established based on protein precipitation with methanol and then chromatographic separation was achieved using Waters acquity ultra-high-performance liquid chromatography high strength silica T3 column, which was stable and sensitive especially for cyanocobalamin. Limit of quantification, precision, trueness, and matrix effect were validated according to the European Medicines Agency and United States Food and Drug guidelines and Clinical and Laboratory Standards Institute guidelines on bioanalytical method. The limit of quantification for thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxic acid, biotin, 5-methyltetrahydrofolate, and cyanocobalamin was 0.4, 0.4, 0.8, 2.0, 0.4, 0.1, 0.4, and 0.04 ng/mL separately, respectively. Intra- and interday precisions were 1.1%-12.4% and 2.0%-13.5%, respectively. The relative errors were between 0.3% and 13.3%, and the matrix effects were between 2.6% and 10.4%.

Sonochemical synthesis of lanthanum ferrite nanoparticle-decorated carbon nanotubes for simultaneous electrochemical determination of acetaminophen and dopamine.

A new nanocomposite consisting of lanthanum ferrite nanoparticles (LaFeO3 NPs) integrated with carbon nanotubes (CNTs) was fabricated via facile sonochemical approach. The engineered nanocomposite was applied to simultaneously determine acetaminophen (ACP) and dopamine (DA) in a binary mixture. The LaFeO3 NPs@CNT probe possesses several advantages such as superior conductivity, large surface area, and more active sites, improving its electrocatalytic activity towards ACP and DA. Under optimized conditions, the anodic peak currents (Ipa) linearly increased with increasing concentration of ACP and DA in the range 0.069-210 µM and 0.15-210 µM, respectively. The sensitivity of LaFeO3 NPs@CNTs/glassy carbon electrode (GCE) for detecting ACP and DA is 7.456 and 5.980 µA·µM-1·cm-2, respectively. The detection limits (S/N = 3) for ACP and DA are 0.02 µM and 0.05 µM, respectively. Advantages of LaFeO3 NPs@CNTs/GCE for the detection of ACP and DA include wide linear ranges, low-detection limits, good selectivity, and long-term stability. The as-fabricated electrode was applied to determine ACP and DA in pharmaceutical formulations and human serum samples with recoveries ranging from 97.7 to 103.3% and an RSD that did not exceed 3.7%, confirming the suitability of the proposed sensor for the determination of ACP and DA in real samples. This study not only presents promising opportunities for enhancing the sensitivity and stability of electrochemical sensors used in the detection of bioanalytes but also significantly contributes to the progress of unique and comprehensive biochemical detection methodologies.

Electrochemical simultaneous determination of hydroquinone, catechol, bisphenol A, and bisphenol S using a novel mesoporous nickel-modified carbon sensor.

The widespread occurrence of endocrine disruptor compounds in wastewater has garnered significant attention owing to their toxicity, even at low concentrations, and their persistence in the water body. Among various analytical techniques, electrochemical sensors become popular for the environmental monitoring of water pollutants due to their low cost, rapid detection, high sensitivity, and selectivity. In this study, the mesoporous Ni (MNi) material was synthesized with an innovative method using Pluronic™ F-127 as a soft template and applied as a modifier for the simultaneous electrochemical sensing of hydroquinone (HQ), catechol (CC), bisphenol A (BPA), and bisphenol S (BPS). MNi with high porosity efficiently enhanced the redox-active surface area and conductivity of the glassy carbon electrode contributing to a significantly improved sensitivity in the detection of target chemicals. The pore size and surface area of MNi were estimated based on atomic force microscopy and Brunauer Emmett and Teller techniques to be ∼14.2 nm and 31.1 m2 g-1, respectively. The limit of detection for HQ, CC, BPA, and BPS was determined to be 5.3, 5.7, 5.6, and 61.5 nM, respectively. The electrochemical sensor presented in this study holds promise as a platform for developing portable and miniaturized tools offering the rapid and sensitive detection of these hazardous phenolic compounds in environmental water samples.

Synthesis of Graphene Oxide-Coupled CoNi Bimetallic MOF Nanocomposites for the Simultaneous Analysis of Catechol and Hydroquinone.

Herein, a three-dimensional flower-like cobalt-nickel bimetallic metal-organic framework (CoNi-MOF) coupled with two-dimensional graphene oxide (GO) nanocomposites was successfully synthesized for the selective and simultaneous electrochemical determination of catechol (CC) and hydroquinone (HQ). The three-dimensional flower-like structure of the CoNi-MOF/GO nanocomposite has a multilayer structure and a large surface area, which greatly improves its electrocatalytic activity towards CC and HQ. Differential pulse voltammetry (DPV) results showed that the peak-to-peak separation of CC (0.223 V) and HQ (0.120 V) was 103 mV at a CoNi-MOF/GO modified glassy carbon electrode (CoNi-MOF/GO/GCE), suggesting that the proposed modified electrode can selectively and simultaneously determine them. Under optimal conditions, the CoNi-MOF/GO/GCE showed an excellent analytical performance for the simultaneous determination of CC and HQ, including a wide linear range (0.1-100 µM), low detection limit (0.04 µM for HQ and 0.03 µM for CC) and high anti-interference ability. As expected, the developed modified electrode has been used to analyze CC and HQ in river water, with acceptable results.

Development of Simultaneous Determination Method of Pesticide High Toxic Metabolite 3,4-Dichloroaniline and 3,5 Dichloroaniline in Chives Using HPLC-MS/MS.

3,4-dichloroaniline (3,4-DCA) and 3,5-dichloroaniline (3,5-DCA) are, respectively, the primary metabolites deriving from the breakdown of phenylurea herbicides and dicarboximide fungicides in both soils and plants, whose residues in vegetable products have a heightened concern considering their higher health risks to humans and greater toxicity than the parent compounds in the environment. In this study, a sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of 3,4-DCA and 3,5-DCA residues in chive products based on the optimization of HPLC-MS/MS chromatographic and mass-spectrometric conditions using the standard substances and the modified QuEChERS preparation technique. The preparation efficiency of 3,4-DCA and 3,5-DCA from chive samples showed that acetonitrile was the best extractant. The combination of the purification agent graphite carbon black + primary secondary amine and the eluting agent acetonitrile + toluene (4:1, v/v) had a satisfactory purification effect. The linear correlation coefficients (R2) were more than 0.996 with the six concentration range of 0.001-1.000 mg/L for 3,4-DCA and 3,5-DCA. The limit of detection and limit of quantitation of this method was 0.6 and 2.0 µg/kg for 3,4-DCA, as well as 1.0 and 3.0 µg/kg for 3,5-DCA, respectively. The matrix effect range of 3,4-DCA and 3,5-DCA in chive tissues was from -9.0% to -2.6% and from -4.4% to 2.3%, respectively. The fortified recovery of 3,4-DCA and 3,5-DCA in chive samples at four spiked levels of 0.001-1.000 mg/kg was 75.3-86.0% and 78.2-98.1%, with the relative standard deviation of 2.1-8.5% and 1.4-11.9%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.6, 2.0, and 1.0, 3.03 for 4-DCA and 3,5-DCA, respectively. This study highlights that the analytical method established here can efficiently and sensitively detect residues of 3,4-DCA and 3,5-DCA residues for monitoring chive products. The method was successfully applied to 60 batches of actual vegetable samples from different regions.

Simultaneous Determination of Uric Acid and Caffeine by Flow Injection Using Multiple-Pulse Amperometry.

The present study reports the development and application of a flow injection analysis (FIA) system for the simultaneous determination of uric acid (UA) and caffeine (CAF) using cathodically pretreated boron-doped diamond electrode (CPT-BDD) and multiple-pulse amperometry (MPA). The electrochemical profiles of UA and CAF were analyzed via cyclic voltammetry in the potential range of 0.20-1.7 V using 0.10 mol L-1 H2SO4 solution as supporting electrolyte. Under optimized conditions, two oxidation peaks at potentials of 0.80 V (UA) and 1.4 V (CAF) were observed; the application of these potentials using multiple-pulse amperometry yielded concentration linear ranges of 5.0 × 10-8-2.2 × 10-5 mol L-1 (UA) and 5.0 × 10-8-1.9 × 10-5 mol L-1 (CAF) and limits of detection of 1.1 × 10-8 and 1.3 × 10-8 mol L-1 for UA and CAF, respectively. The proposed method exhibited good repeatability and stability, and no interference was detected in the electrochemical signals of UA and CAF in the presence of glucose, NaCl, KH2PO4, CaCl2, urea, Pb, Ni, and Cd. The application of the FIA-MPA method for the analysis of environmental samples resulted in recovery rates ranging between 98 and 104%. The results obtained showed that the BDD sensor exhibited a good analytical performance when applied for CAF and UA determination, especially when compared to other sensors reported in the literature.

Molecularly imprinted polymer dual electrochemical sensor for the one-step determination of albuminuria to creatinine ratio (ACR).

The urinary albumin to creatinine ratio (ACR) is a convenient and accurate biomarker of chronic kidney disease (CKD). An electrochemical sensor for the quantification of ACR was developed based on a dual screen-printed carbon electrode (SPdCE). The SPdCE was modified with carboxylated multiwalled carbon nanotubes (f-MWCNTs) and redox probes of polymethylene blue (PMB) for creatinine and ferrocene (Fc) for albumin. The modified working electrodes were then molecularly imprinted with coated with polymerized poly-o-phenylenediamine (PoPD) to form surfaces that could be separately imprinted with creatinine and albumin template molecules. The seeded polymer layers were polymerized with a second coating of PoPD and the templates were removed to form two different molecularly imprinted polymer (MIP) layers. The dual sensor presented recognition sites for creatinine and albumin on different working electrodes, enabling the measurement of each analyte in one potential scan of square wave voltammetry (SWV). The proposed sensor produced linear ranges of 5.0-100 ng mL-1 and 100-2500 ng mL-1 for creatinine, and 5.0-100 ng mL-1 for albumin. LODs were 1.5 ± 0.2 ng mL-1 and 1.5 ± 0.3 ng mL-1, respectively. The dual MIP sensor was highly selective and stable for seven weeks at room temperature. The ACRs obtained using the proposed sensor compared well (P > 0.05) with the results from immunoturbidimetric and enzymatic methods.

HPLC analysis of 16 compounds from Artemisia ordosica.

Objective: To establish a high-performance liquid chromatographic method (HPLC) for the simultaneous determination of 16 compounds from Artemisia ordosica. Methods: HPLC was used to analyze 16 quality indicators of A. ordosica. The HPLC conditions were as follows: Agilent Eclipse Plus C18 column (250 mm × 4.6 mm, 5 µm) with acetonitrile (A)-water (B) as mobile phase, gradient elution: 0-10 min, 75%-65% B; 10-30 min, 65%-35% B; and finally 30-40 min, 35%-15% B. The flow rate was 1.0 mL/min, the column temperature was 40 °C, the injection volume was 10 µL, and monitored by absorbance at 285 nm for compounds 1-10, 12 and 225 nm for compounds 11, 13-16. Results: Under the selected experimental chromatographic conditions, compounds 1-16 showed good linearity (r > 0.9993) in a wide concentration range. Their average recoveries were 99.50%, 95.38%, 97.75%, 96.00%, 98.20%, 97.50%, 95.50%, 99.33%, 96.75%, 96.50%, 98.50%, 97.83%, 99.20%, 95.33%, 97.33% and 96.30%, respectively, and the RSD were 1.99%, 1.81%, 1.63%, 1.98%, 1.67%, 1.92%, 1.74%, 1.67%, 1.90%, 1.72%, 1.88%, 1.83%, 1.79%, 1.76%, 1.81% and 1.96%, respectively. Conclusion: Based on the results of the HPLC analysis, it was concluded that p-hydroxycinnamic acid (1), O-hydroxycinnamic acid (2), coniferyl alcohol (5), 5,4'-dihydroxy-7,3'-dimethoxyflavanone (8), 5,4'-dihydroxy-7-methoxyflavanone (9), 5-hydroxy-7,4'-dimethoxyflavanone (12), dehydrofalcarindiol (13), arteordoyn A (14), dehydrofalcarinol (15) and capillarin (16) are best suited for the role of quality indicators of A. ordosica grown in different ecological environments.

Simultaneous quantification of pirarubicin, doxorubicin, cyclophosphamide, and vincristine in human plasma of patients with non-Hodgkin's lymphoma by LC-MS/MS method.

Pirarubicin (THP), doxorubicin (DOX), cyclophosphamide (CTX), and vincristine (VCR) are widely used in the treatment of patients with non-Hodgkin's Lymphoma. Herein, a precise and sensitive method was developed for the determination of THP, DOX, CTX and VCR in human plasma by high-performance liquid-chromatography-tandem mass spectrometry (LC-MS/MS). Liquid-liquid extraction was applied to extract THP, DOX, CTX, VCR, and the internal standard (IS, Pioglitazone) in plasma. Agilent Eclipse XDB-C18 (3.0 mm × 100 mm) was utilized and chromatographic separation was obtained in eight minutes. Mobile phases were composed of methanol and buffer (10 mM ammonium formate containing 0.1% formic acid). The method was linear within the concentration range of 1-500 ng/mL for THP, 2-1000 ng/mL for DOX, 2.5-1250 ng/mL for CTX, and 3-1500 ng/mL for VCR. The intra- and inter-day precisions of QC samples were found to be below 9.31 and 13.66%, and accuracy ranged from -0.2 to 9.07%, respectively. THP, DOX, CTX, VCR and the internal standard were stable in several conditions. Finally, this method was successfully utilized to simultaneously determine THP, DOX, CTX and VCR in human plasma of 15 patients with non-Hodgkin's Lymphoma after intravenous administration. Finally, the method was successfully employed in the clinical determination of THP, DOX, CTX, and VCR in patients with non-Hodgkin lymphoma after administration of RCHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) regimens.

Hybrid Nanomaterial of Graphene Oxide Quantum Dots with Multi-Walled Carbon Nanotubes for Simultaneous Voltammetric Determination of Four DNA Bases.

In this proof-of-concept study, a novel hybrid nanomaterial-based electrochemical sensor was developed for the simultaneous detection of four DNA bases. For the modification of the working electrode surface, graphene oxide quantum dots (GOQDs) were synthesized using a solvothermal method. GOQDs were then used for the preparation of a hybrid nanomaterial with multi-walled carbon nanotubes (GOQD-MWCNT) using a solvothermal technique for the first time. Transmission electron microscopy (TEM) was used to characterize the GOQDs-MWCNTs. A glassy carbon electrode (GCE) was modified with the GOQDs-MWCNTs using Nafion™ to prepare a GOQD-MWCNT/GCE for the simultaneous determination of four DNA bases in phosphate buffer solution (PBS, pH 7.0) using differential pulse voltammetry (DPV). The calibration plots were linear up to 50, 50, 500, and 500 µM with a limit of detection at 0.44, 0.2, 1.6, and 5.6 µM for guanine (G), adenine (A), thymine (T) and cytosine (C), respectively. The hybrid-modified sensor was used for the determination of G, A, T, and C spiked in the artificial saliva samples with the recovery values ranging from 95.9 to 106.8%. This novel hybrid-modified electrochemical sensor provides a promising platform for the future development of a device for cost-effective and efficient simultaneous detection of DNA bases in real biological and environmental samples.

Development of an HPLC-PDA Method for the Determination of Capsanthin, Zeaxanthin, Lutein, ß-Cryptoxanthin and ß-Carotene Simultaneously in Chili Peppers and Products.

For the better standardization and widespread application of the determination method of carotenoids in both chili peppers and their products, this work reports for the first time the simultaneous determination of five main carotenoids, including capsanthin, zeaxanthin, lutein, ß-cryptoxanthin and ß-carotene in chili peppers and their products, with optimized extraction and the high-performance liquid chromatography (HPLC) method. All parameters in the methodological evaluation were found to be in good stability, recovery and accuracy compliance with the reference values; the R coefficients for the calibration curves were more than 0.998; and the LODs and LOQs varied from 0.020 to 0.063 and from 0.067 to 0.209 mg/L, respectively. The characterization of five carotenoids in chili peppers and their products passed all the required validation criteria. The method was applied in the determination of carotenoids in nine fresh chili peppers and seven chili pepper products.

Simultaneous Determination of Xanthine and Hypoxanthine Using Polyglycine/rGO-Modified Glassy Carbon Electrode.

A novel electrochemical sensor was developed for selective and sensitive determination of xanthine (XT) and hypoxanthine (HX) based on polyglycine (p-Gly) and reduced graphene oxide (rGO) modified glassy carbon electrode (GCE). A mixed dispersion of 7 µL of 5 mM glycine and 1 mg/mL GO was dropped on GCE for the fabrication of p-Gly/rGO/GCE, followed by cyclic voltammetric sweeping in 0.1 M phosphate buffer solution within -0.45~1.85 V at a scanning rate of 100 mV·s-1. The morphological and electrochemical features of p-Gly/rGO/GCE were investigated by scanning electron microscopy and cyclic voltammetry. Under optimal conditions, the linear relationship was acquired for the simultaneous determination of XT and HX in 1-100 µM. The preparation of the electrode was simple and efficient. Additionally, the sensor combined the excellent conductivity of rGO and the polymerization of Gly, demonstrating satisfying simultaneous sensing performance to both XT and HX.

Magnetic Fe3O4 nanoparticles decorated phosphorus-doped biochar-attapulgite/bismuth film electrode for smartphone-operated wireless portable sensing of ultra-trace multiple heavy metal ions.

Pollution caused by both forestry wastes and heavy metals has increasingly drawn attention owing to environmental safety concerns. After essential oil is extracted from Cinnamomum camphoras (L.), the branches are used as forestry wastes to prepare a phosphorus-doped biochar-attapulgite/bismuth film electrode decorated with magnetic Fe3O4 nanoparticles (MBA-BiFE). The smartphone-operated wireless portable sensor is employed for the simultaneous ultratrace voltammetric detection of multiple heavy metal ions (Cd2+, Pb2+, and Hg2+). Cd2+, Pb2+, and Hg2+ exhibit excellent electrochemical responses in linear ranges of 0.1 nM-5 µM, 0.01 nM-7 µM, and 0.1 nM-3 µM with limits of detection equal to 0.036, 0.003, and 0.011 nM, respectively. The recoveries of MBA-BiFE for Cd2+, Pb2+, and Hg2+ are 93.6-109.9%, 86.0-107.5%, and 94.8-104.6%, respectively, and the RSD values for repeated measurements of Cd2+, Pb2+, and Hg2+ are 4.2%, 2.8%, and 3.3%, respectively. A machine learning model based on an artificial neural network algorithm is constructed to enable a smart determination of ultratrace hazardous multiple metal ions. The portable sensor based on the screen-printed integrated three-electrode sensor modified using MBA-BiFE demonstrates advantages and practicability in outdoor detection, compared with conventional sensors based on MBA-BiFE. This study provides a smartphone-operated wireless portable sensing technique for high-potential applications in environmetallomics or agrometallomics using forestry waste-derived biochar as substrate for electrode preparation. HIGHLIGHTS: • Fe3O4 decorated phosphorus-doped biochar-attapulgite/bismuth film electrode. • A smartphone-operated sensor for analysis of multiple heavy metal ions. • An Artificial neural network model for smart analysis of Cd2+, Pb2+, and Hg2+.

Construction of a nano dispersed Cr/Fe-polycrystalline sensor via high-energy mechanochemistry for simultaneous electrochemical determination of dopamine and uric acid.

A bimetallic polycrystalline sensor (Cr/Fe-SNCM) having nanosized and high dispersion was designed and used for the electrochemical simultaneous determination of dopamine (DA) and uric acid (UA). Catalytic nanosized Cr/Fe were highly anchored on N/S/O-contained porous carbon with high dispersion and polycrystalline Cr/Fe via energetic mechanochemical method and high-temperature carbonization. The obtained Cr/Fe-SNCM exhibited high graphitized carbon supporter and endowed high electron transport and signal output for the whole sensor. Moreover, highly dispersed Cr/Fe sites and the polycrystalline form (metal-N/S/O) efficiently enhanced the catalytic reaction, leading to a limits of detection (based on the 3σ/m criterion) of 25.8 and 22.5 nM for DA and UA, respectively. This is 1-2 orders of magnitude lower than many state-of-the-art reported sensors. The Cr/Fe-SNCM1.0 sensor exhibited wide working range (0.1 to 10.0 µM), high recovery (96-103%) and low relative standard deviation (RSD = 3.2-4.7%) for DA and UA in real serum samples, possessing high significance for practical large-scale applications.

One-step fluorometric determination of multiple-component dissolved organic matter in aquatic environments.

Dissolved organic matter (DOM) is ubiquitous in aqueous environments and is composed of different components that play different but important roles in the migration and the fate of pollutants, emergence of the disinfect byproduct, thus requiring quantitative characterization. However, until now, simultaneous quantification of the main contents in DOM, i.e., saccharides, proteins, and humic substances, has been difficult, impeding us from understanding and predicting the environmental behaviors of typical pollutants. In this work, a fluorescence approach based on the excitation emission matrix (EEM), combined with a new algorithm, denoted matrix reconstruction coupled with prior linear decomposition (MR-PLD), was developed to quantify multiple DOM simultaneously. First, a set of simulated water samples consisting of glucose, tryptones, and humic acid (HA) were analyzed using MR-PLD to validate the feasibility of the method. The DOM components could be reliably determined with a higher accuracy than parallel factor analysis (PARAFAC) and Parallel Factor Framework-Linear Regression (PFFLR), also with a more convenient procedure than conventional PLD. Second, both actual simulated and experimental methods were performed to test the anti-interference performance of MR-PLD, indicating that the quantification of DOM would not be significantly impacted by other fluorophores. Finally, several actual water samples from natural waters and wastewater treatment plants were also analyzed to confirm the robustness of this method in actual aqueous environments. This study provides a new approach to characterize DOM with EEM, contributing to its convenient concentration monitoring and the further exploration of the environmental impacts.

A label-free dual immunosensor for the simultaneous electrochemical determination of CA125 and HE4 biomarkers for the early diagnosis of ovarian cancer.

The blood levels of cancer antigen 125 (CA125) and human epididymal secretory protein 4 (HE4) are measured in the diagnosis and progression monitoring of ovarian cancer (OC), and the Risk of Ovarian Malignancy Algorithm (ROMA) score% values are calculated for cancer risk assessment. For the first time, disposable dual screen-printed carbon electrodes modified with reduced graphene oxide, polythionine, and gold nanoparticles were used to fabricate label-free electrochemical dual CA125-HE4 immunosensors for the sensitive, fast, and practical simultaneous determination of CA125 and HE4. DPV and SWV methods were used to simultaneously determine antigens in two different linear ranges (1-100 pg mL-1 and 1-50 ng mL-1). High sensitivity, low LOD, and LOQ were obtained for two linear ranges with a correlation coefficient above 0.99. The application stability of the dual CA125-HE4 immunosensors was determined as 60 days, and the storage stability was determined as 16 weeks. The dual immunosensors exhibited high selectivity in eight different antigen mixtures. The reusability of the dual immunosensors has been tested up to 9 cycles. ROMA score% values for pre-menopausal and post-menopausal status were calculated using the concentration of CA125 and HE4 in the blood serum and assessing OC risk. The disposable dual immunosensors can be used in point-of-care tests for rapid and practical simultaneous determination of CA125 and HE4 with high selectivity, sensitivity, and repeatability.