Acceptable Repeatability Research Articles

Electrochemical Sensing for Bisphenol A Based on Spinel-Type CuGa2O4 Nanoparticles Modified Electrode

Abstract Spinel-type CuGa2O4 nanoparticles were synthesized via hydrothermal-calcination technique. The morphologies of nanoparticles were characterized by X-ray diffraction spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electrochemical behavior of bisphenol A (BPA) was investigated at CuGa2O4 nanoparticles modified glassy carbon electrode (CuGa2O4/GCE) under alkaline condition. The results showed that CuGa2O4 nanoparticles had apparent electrocatalytical effect on the oxidation of BPA. Different electrochemical methods including cyclic voltammetric, square wave voltammetric and chronoamperometric techniques could be used for the sensitive detection of BPA, and chronoamperometric methods exhibited the best performance. At the optimal condition, the concentration of BPA varied linearly with the electrochemical signal in the range of 5-60 nM with a correlation coefficient of 0.999, and the detection limit was determined as 2 nM (S/N=3). Furthermore, the fabricated sensor exhibited acceptable repeatability and had been successfully used to detect BPA in real water sample.

Determination of flow angle from measurements of vortex shedding frequency downstream of a triangular bluff model using a single-sensor hot-wire probe

Experimental aerodynamic studies often require precise measurements of flow angles. However, the conventional multi-hole probe is unsuitable for measuring small flow angles or for use under low-velocity conditions. To overcome these limitations, a new method has been proposed based on measuring the frequency of vortex shedding downstream of a non-polar symmetric body. This technique utilizes a single-sensor hot-wire probe to measure the frequency of the vortex shedding from an equilateral triangular model at different flow angles ( by rotating the model using a rotating mechanism. Subsequently, the Strouhal number (St) is determined for each flow angle from the measured vortex shedding frequencies. An empirical correlation is then obtained between the Strouhal number and the flow angle of the form , considering the condition where the Strouhal number is solely a function of the flow angle. The range of flow angles for which the proposed method is applicable, along with acceptable repeatability of the vortex shedding frequency and suitable Strouhal number sensitivity to the variations in the flow angle, was determined. An empirical correlation was established, which can be used to determine flow angles in the range of ±10° with an accuracy of 1°. For this purpose, the triangular model is fixed at an angle of 33° to the principal coordinates. The probe is positioned downstream of the model in the defined range: , , where is the side of the equilateral triangular model, and and are probe distances in the flow and perpendicular to the flow direction.

Portable Mini-Electrochemical Cell: Integrating Microsampling and Micro-Electroanalysis for Multipurpose On-Site Nitrite Sensing.

In modern analytical chemistry, one of the primary goals is to develop miniaturized, easy-to-use sensing tools, particularly those with multitasking capabilities. In this work, we designed a mini-voltammetric cell that integrates a modified Au microelectrode (Au/Au NPs as the working electrode) and an Ag/AgCl reference electrode installed within a micropipette tip. This combined tool not only enables portable and on-site microvolume sampling─requiring only a microvolume (around 20-40 μL) or a single droplet─but also facilitates direct micro-electroanalysis in a short time. To evaluate its capabilities, the mini-voltammetric cell was optimized for trace analysis of nitrite ions and demonstrated linear responses in the ranges of 20-150 and 150-1200 μM, with an acceptable limit of detection (LOD) of 18.40 μM, meeting both WHO and EPA standards for nitrite levels. Furthermore, it exhibited high selectivity, stability (up to 36 continuous measurements with only a 3.24% signal drop), and acceptable repeatability (RSD of 2.98%, n = 15). The analytical performance of this miniaturized tool was further assessed through the sampling and detection of nitrite ions in various real samples with different matrixes: (1) urine samples, for the fast diagnosis of urinary tract infections (UTIs), where nitrite ions are detected as biomarkers of UTIs; (2) river water polluted with agricultural waste, where nitrite ions serve as pollutants from nitrogen fertilizers; and (3) on the hands and in forensic investigations, where nitrite ions are detected as indicators of gunshot residue, crucial in crime scene examinations. All real samples were analyzed using the standard addition method and recovery tests, yielding acceptable results. Additionally, the proposed mini-analytical tool was evaluated for its sustainability and applicability using two recognized metrics: The Green Analytical Procedure Index (GAPI) and the Blue Applicability Grade Index (BAGI). The results confirmed that this method can be classified as both a green analytical method and highly applicable. Finally, the practical results demonstrated that the proposed miniaturized electroanalytical tool exhibits reliable performance, high sensitivity and selectivity, and fast response in the on-site microanalysis of nitrite, without the need for any reagents or complex sampling steps, across different real samples (such as clinical, forensic, and environmental samples). We believe the proposed mini-voltammetric cell could be used as an alternative to current detection methods, and with suitable modifications, it could be adapted for the microanalysis of other applications and (bio)targets with small volumes in the near future.

Rapid quantitative analysis of semi-volatile organic compounds in indoor surface film using direct analysis in real time mass spectrometry: a case study on phthalates

Abstract. Direct analysis in real time mass spectrometry (DART-MS) has recently emerged as a promising approach for measuring semi-volatile organic compounds (SVOCs) on indoor surface films. However, its broader application in indoor environments is limited by low measurement repeatability and no separation of isomers. Herein we developed a sampling suite of indoor surface films for DART-MS analysis, optimized settings of DART to obtain higher analytical performance, and demonstrated the possibility of separating isomeric compounds using tandem mass spectrometry (MS/MS). Two pairs of isomeric phthalate esters, including di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) and diisobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP), were used as examples for method optimization and validation. Under optimized conditions, the instrument responses for all four compounds exhibited good linearity (r>0.992) and acceptable repeatability (intraday relative standard deviation (RSD) < 11.0 %). The limits of quantification for the four phthalate esters ranged from 0.042 to 0.24 ng cm−2. The uncertainty in the separation of isomeric components using MS/MS was < 11.4 %, which is acceptable for real sample analysis. To further assess the developed method, we analyzed 10 film samples collected side by side in an occupied office. DnOP was not detected. The RSD among samples was 6.1 % for DEHP, 4.6 % for DnBP, and 10.4 % for DiBP, indicating the overall good repeatability of the collection and measurement method developed. With improved performance, the developed method increases the feasibility of the DART-MS technique for monitoring the dynamics of chemical composition of indoor surface films.

Polydopamine-modified 3D flower-like ZnMoO4 integrated MXene-based label-free electrochemical immunosensor for the food-borne pathogen Listeria monocytogenes detection in milk and seafood

Listeria monocytogenes is a gram-positive bacterium that causes listeriosis in humans. This contaminates the ready-to-eat food products and compromises their safety. Thus, detecting its presence in food samples with high sensitivity and reliability is necessary. Herein, we propose a label-free electrochemical immunosensor based on a mussel-inspired polydopamine-modified zinc molybdate/MXene (PDA@ZnMoO4/MXene) composite for effective and rapid detection of L. monocytogenes in food products. Spectrophotometry approaches were employed to examine the resulting composites. Voltammetry and impedimetry techniques were used to confirm the step-by-step assembly of the immunosensor and its sensitive detection of L. monocytogenes in various food products, such as milk and smoked seafood. The results demonstrated the practicality of the constructed immunosensor, with an appreciable linearity of 10–107 CFU/ml and a reasonably low detection limit (LOD, 12 CFU/ml). Moreover, the immunosensor exhibited excellent selectivity for microbial cocktails and acceptable repeatability, reproducibility, and storage stability. Thus, we believe that the proposed sensitive, reliable, and label-free immunosensor based on the PDA surface modification technique for detecting L. monocytogenes can be extended to monitor various food-borne pathogens to ensure food safety.

A-020 Evaluation of the QuidelOrtho Diagnostics Vitros NT-proBNP II Assay

Abstract Background N-terminal-proBNP (NT-proBNP), a short peptide originating from the cleavage of proBNP by Corin, can be used as a diagnostic test in individuals presenting with signs and symptoms consistent with heart failure (HF). QuidelOrtho Diagnostics released its latest reformulation of its NT-proBNP assay, the Vitros NT-proBNP II assay. The analytical performance of this assay was evaluated. Methods Repeatability, reproducibility, and carryover were assessed using quality control material. The analytical measuring range and clinical reportable range (AMR and CRR) were assessed using commercially available material and diluted patient samples. Accuracy was assessed by comparing results from the Vitros NT-proBNP II assay and results from the Vitros NT-proBNP assay. Instrument-to-instrument comparison was performed by comparing results from the NT-proBNP II assay from two different Vitros 5600 chemistry analyzers. Paired heparin and EDTA plasma samples were assessed for specimen type comparison. Results Repeatability and reproducibility were <=10% CV and no carryover was observed. The AMR was 20 - 30,000 pg/mL and the CRR extended the range to 600,000 pg/mL. Passing-Bablok analysis showed a significant proportional bias with a slope of 1.34 for samples up to 12,000 pg/mL (Vitros NT-proBNP). Vendor-performed comparison studies showed no significant proportional bias with a slope of 1.06 using unweighted Deming analysis for samples up to 20,700 pg/mL (Vitros NT-proBNP). Instrument-to-instrument and heparin-to-EDTA plasma comparisons showed no significant biases. Conclusions The NTproBNP II assay showed acceptable repeatability, reproducibility, and no carryover. The AMR analysis verified the measuring range in the IFU of the assay and the CRR is extended to 600,000 pg/mL. Results were very comparable between two different Vitros 5600s and between paired heparin and EDTA plasma specimens. Comparison between the Vitros NT-proBNP and Vitros NT-proBNP II assays showed a very significant proportional bias (slope of 1.34) for specimens up to 12,000 pg/mL measured on the Vitros NT-proBNP assay, but the proportional bias is less significant at higher NT-proBNP values (>20,000 pg/mL, Vitros NT-proBNP) are included in the analysis. There may be a significant matrix effect or interference at lower NT-proBNP concentrations with the reformulated reagent, which may be less prominent when NT-proBNP is present at much higher concentrations.

Investigation of induced electroosmotic flow in small-scale capillary electrophoresis devices: Strategies for control and reversal.

Electroosmotic flow (EOF) is the bulk flow of solution in a capillary or microchannel induced by an applied electric potential. For capillary and microchip electrophoresis, the EOF enables analysis of both cations and anions in one separation and can be varied to modify separation speed and resolution. The EOF arises from an electrical double layer at the capillary wall and is normally controlled through the pH and ionic strength of the background buffer or with the use of additives. Understanding and controlling the electrical double layer is therefore critical for maintaining acceptable repeatability during method development. Surprisingly, in fused silica capillaries at low pH, studies observe an EOF even though the capillary surface should be neutralized. Previous work has suggested the presence of an "induced electroosmotic flow" from radial electric fields generated across the capillary wall due to the separation voltage and grounded components external to the capillary. Using thin-wall (15µm) fused silica separation capillaries to facilitate the study of radial fields, we show that the EOF mobility depends on both the separation voltage and the location of external grounds. This is consistent with the induced EOF model, in which radial electric fields embed positive charges at the capillary walls to create an electrical double layer. The magnitude of the effect is characterized and shown to have long-range influences that are difficult to completely null by moving grounded components away from the separation capillary. Instead, active EOF control using externally applied potentials or a passive approach using a negative separation voltage are discussed as two possible methods for controlling the induced EOF. Both methods can reverse the EOF and improve the resolution and peak efficiency in amino acid separations.

Are there laterality differences in passive flexion and extension of the proximal limb joints in working Siberian Husky dogs?

Differences between left and right-side joint range of motion may affect canine locomotive ability and movement. Passive range of motion (PROM) joint measurement provides the limits that a particular joint can move in its physiological planes of motion without influence of muscle activity. To compare left and right-side flexion and extension of the glenohumeral, humeroulnar/humeroradial, coxofemoral and femorotibial joints and for laterality PROM differences. Siberian Husky dogs were selected (n = 18) of mixed gender, aged (1.4–11.8) years living and working together from a single kennel. Joint PROM was measured using goniometry, a validated, non-invasive method, by the same investigator previously tested for acceptable measurement repeatability. Dogs were conscious and placed in standing position. Triplicate measures of joint flexion and extension were taken on both sides of each dog for afore-mentioned joints. Median values of triplicate measures were computed. Paired t-tests compared laterality of joint PROM, gender, age (< 6 vs. > 6 years) effects. Inferential symmetry indices [SI] were calculated. There was no significant difference (p > 0.05) between left and right-side flexion and extension measures for all joints. Gender had no significant effect (p > 0.05) on joint flexion or extension measures for all joints. Age (< 6 vs. > 6 years) had a significant effect on right hip flexion (p < 0.001) and for both left and right-side shoulder flexion (p < 0.001); elbow flexion (p = 0.001 and p < 0.001); hip extension (p = 0.02 and p < 0.001) respectively. The shoulder joint showed greatest PROM asymmetry (SI = 3.63%). Bilateral PROM measures are important to consider in joint movement and assessment. These results warrant further investigation with larger cohorts of defined age groups.

Repeatability of a Combined Adaptive Optics Visual Simulator and Hartman-Shack Aberrometer in Pseudophakic Eyes With and Without Previous Corneal Refractive Surgery.

To evaluate the intrasession repeatability of wavefront aberrations obtained by a combined adaptive optics visual simulator and Hartman-Shack aberrometer in pseudophakic eyes with and without previous corneal refractive surgery. Three consecutive measurements were performed in one eye of each individual. Total ocular aberrations were recorded up to the 5th Zernike order for a 4.5-mm pupil. Repeatability was assessed by calculating the within-subject standard deviation (Sw), the repeatability limit (R), and the intraclass correlation coefficient (ICC). Vector analysis was performed to assess astigmatism variability between scans. The study enrolled 32 normal individuals and 24 individuals with a history of refractive surgery. In normal and eyes that had previous refractive surgery, respectively, the Sw values were 0.155 and 0.176 diopters (D) for sphere and 0.184 and 0.265 D for cylinder. The Sw values for all 3rd order terms ranged from 0.037 to 0.047 µm in normal eyes and 0.044 to 0.063 µm in eyes that had previous refractive surgery. The Sw for primary spherical aberration was 0.020 µm in normal eyes and 0.026 µm in eyes that had previous refractive surgery. ICC values for measurements of astigmatism yielded larger variability (ICC = 0.751 and 0.879). However, both groups demonstrated excellent repeatability (ICC > 0.9) for root mean square higher order aberrations (RMS-HOA) and total RMS values. In pseudophakic eyes, the adaptive optics Hartmann-Shack device demonstrated acceptable repeatability for measurement of sphere and 3rd and 4th order HOAs with higher variability for astigmatism measurements, especially in eyes with a prior history of corneal refractive surgery. [J Refract Surg. 2024;40(9):e645-e653.].

Electrochemical aptasensor based on RGO/PPy/Au*NPs for diagnostic biosensing of SARS-CoV-2 in clinical samples: Experimental and molecular dynamics simulations approaches

A highly sensitive and selective E-DNA biosensor was fabricated on a gold substrate using a reduced graphene oxide/polypyrrole/gold nanoparticle/oligonucleotide (RGO/PPy/Au*NPs/Apt) nanocomposite electrode to detect the nucleocapsid protein of SARS-CoV-2 in the patient blood plasma. The modified electrode was characterized by physicochemical techniques such as Fourier transform-infra red (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS) analyses, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) analyses. Moreover, electrochemical analyses were employed to study the electrochemical performance of the electrodes including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). Computational investigations of N protein bindings such as hydrogen bonding, Van der Waals binding, and Gibbs binding energies of the N-protein, and aptamer were studied by Molecular Dynamics Simulations (MDS). The unique synergistic effect of RGO, PPy, and the well-known effect of Au nanoparticles makes the DNA probe immobilized on the gold electrode surface. After optimizing the systems, the E-DNA biosensor exhibited a fast SWV response, higher sensitivity (33.77 μA.nM−1.cm−2) and selectivity, high efficiency, good storage stability, and acceptable repeatability for monitoring DNA. The results of real samples based on SWV indicated the correct functioning of the aptasensor in the presence of the SARS-CoV-2 virus. The limit of detection was 3.16×10−17 M and the limit of quantitation was 1.42×10−16 M. The MDS results indicated the stable dynamic folding of the aptamer for beneficial binding. The results indicated that the RGO/PPy/Au*NPs/Apt biosensor is promising for detecting of SARS-CoV-2 virus.

Preparation and characterisation of NH3 gas sensor based on PANI/Fe-doped CeO2 nanocomposite

PANI/Fe-doped CeO2nanocomposite was synthesised by the in-situ process. The produced powders were characterised by XRD, XPS, FT-IR, Raman, HRTEM and SEM-EDS tests. The sensors' function was based on PANI/Fe-doped CeO2nanocomposite with thin film deposited on top of interdigitated electrodes (IDT). NH3 detection with PANI/Fe-doped CeO2 nanocomposite sensor could be successfully performed even at room temperature (RT) and relative humidity of 45 %. Results demonstrated that PANI/Fe-doped CeO2 might be promising sensing materials for detecting the low NH3 concentration (ppm). In addition, the sensor is selective to the interfering gases, including CO, CO2 and NO2. This sensor displays acceptable repeatability and stability over time.

Electrochemical Oxidation of Ranitidine using a Boron-Doped Diamond Electrode in the Presence of Anionic Surfactant: A Comprehensive Investigation

Ranitidine (RAN) is a drug from the histamine H2 receptor antagonist class and is used to prevent excessive production of stomach acid. An electrochemical investigation of the RAN in pharmaceutical preparation and spiked human urine was performed for the using a boron-doped diamond electrode (BDDE). Voltammetric measurements were performed in a pH 11 BR solution supplemented with the anionic surfactant, sodium dodecyl sulfate (SDS). In the proposed method using optimized experimental conditions, linearity was obtained for RAN in the concentration range of 0.8-50.0 μM. The LOD value obtained is 0.22 μM. Good selectivity, accuracy, precision, and acceptable repeatability were also achieved in this proposed electrochemical sensor. Finally, this electrochemical sensor was successfully used for RAN detection in pharmaceutical samples.

Highly sensitive and flexible ammonia sensor based on PEDOT:PSS doped with Lewis acid for wireless food monitoring

Ammonia serves as a crucial indicator of food spoilage, but current sensors lack sufficient sensitivity, stability, selectivity, and automation for practical on-site and real-time monitoring. A highly sensitive and flexible ammonia sensor based on PEDOT:PSS doped with Lewis acid (FeCl3 solution) for wireless food monitoring is proposed in this study to solve the above limitations. The intercalation effect caused by the diffusion of Fe3+ and hydrolyzed H+ in the film coordinating with SO3− groups present in PSS chains leads to an increased distance between adjacent PEDOT-rich domains. It enhances ammonia sensitivity by providing additional ionic carriers and carrier transport paths within the PEDOT:PSS molecule. The results demonstrated a significant enhancement in the sensitivity of PEDOT:PSS sensor doped with FeCl3, exhibiting a response value of about 25 % at 25 ℃ for 1 ppm NH3, with an impressive detection limit of 0.23 ppm and quantification limit of 0.78 ppm (1–400 ppm). Moreover, it showcases acceptable repeatability both at 1 ppm (RSD = 4.30 %) and 100 ppm ammonia (RSD = 3.61 %), along with the notable selectivity and long-term stability. XPS, Raman analysis, and the density function theory (DFT) calculations further elucidated the sensing mechanism of the sensor towards ammonia. Additionally, a portable wireless detection device was designed, which was equipped with the Bluetooth communication and the micro-controller system to detect the decay process of fresh shrimp, realizing wirelessly real-time monitoring of food freshness through a smart phone. It’s worth noting that the innovative sensing technology holds great promise for food quality monitoring.

Fabrication of SERS composite substrates using Ag nanotriangles-modified SiO2 photonic crystal and the application of malachite green detection

A novel surface-enhanced Raman scattering (SERS) composite substrates on the basis of Ag triangular nanoplates(Ag TNPs)-modified SiO2 photonic crystals (PC) is fabricated and applied to the SERS detection of malachite green (MG). It consists of uniformly arranged Ag TNP@SiO2, a new PC. Notably, Ag TNP are uniformly aligned on the SiO2 surface, forming a three-dimensional high-density hotspot nanostructure. With the tip “hot spots” of Ag TNPs, Bragg diffraction of SiO2 and coupling enhancement between Ag TNPs and SiO2, the SERS enhancement of this composite substrates was multiplied. The effect on the SERS of Ag TNP@SiO2 composite substrate was systematically optimized by tuning Ag TNP size, size of SiO2 microspheres, coverage of Ag TNPs on SiO2 and fabrication method of Ag TNPs and PC. Moreover, the uniform of SERS composite substrates and Raman signal was dramatically increased by the method of vertical deposition. Eventually, the SERS composite substrates were employed in MG detection. Its broad detection range of 1 pM–1 μM and low limit of detection (LOD) of 0.49 pM indicated acceptable sensitivity and repeatability. This work illustrates the promising applicability in food safety analysis based on SERS composite substrates composed by Ag TNP@SiO2 with numerous SERS enhancements and excellent stability.

Frontal and parietal cortices activation during walking is repeatable in older adults based on fNIRS

PurposeThis study aimed to explore the test-retest reliability of fNIRS in measuring frontal and parietal cortices activation during straight walking and turning walking in older adults, in order to provide a theoretical foundation for selecting assessment tools for clinical research on motor control and some diseases such as Parkinson's disease in older adults. Methods18 healthy older participants (69.1 ± 0.7 years) were included in this study. The participants completed straight walking and figure-of-eight turning walking tasks at self-selected speeds. Intra-class correlation coefficients (ICCs) and Bland-Altman scatter plots were used to assess the test-retest reliability of oxyhemoglobin (HbO2) changes derived from fNIRS. p < 0.05 was considered statistically significant. ResultsThe test-retest reliability of HbO2 in prefrontal cortex (ICC, 0.67–0.78) was good and excellent, in frontal motor cortex (ICC, 0.51–0.61) and parietal sensory cortex (ICC, 0.53–0.62) is fair and good when the older adults performed straight and turning walking tasks. Bland-Altman diagram shows that the data consistency is fair and good. ConclusionfNIRS can be used as a clinical measurement method to evaluate the brain activation of the older adults when walking in a straight line and turning, and the results are acceptable repeatability and consistency. However, it is necessary to strictly control the testing process and consider the possible changes in the repeated measurements.

Reliability and Validity of the Persian Nose Obstruction Symptom Evaluation (NOSE) Scale.

The nasal obstruction symptom evaluation (NOSE) scale is a valid and specific questionnaire for evaluating nasal obstruction. The present study aimed to assess the validity of the Persian version of the NOSE questionnaire. The present study is a cross-sectional study conducted from December 2018 to April 2019. In the study group, eligible individuals referred to one clinic and Firoozgar Hospital, Tehran, Iran (a tertiary referral center) were asked to complete the questionnaire once on the first visit and once 3 months after the surgery. In the control group, healthy adults (above 18 years old) were selected among staff, students, residents, or relatives of the project executors. The NOSE questionnaire has 5 questions and a quality chart. The results were compared with the short form of the 12-item GHQ-12 questionnaire that had previously been translated and validated. SPSS 20 software was used to calculate Cronbach's alpha and intra-class correlation coefficient and to examine the convergent and discriminative validities. The results obtained are consistent with the results of the primary research when developing the questionnaire and the results of studies conducted with different versions of the questionnaire in different languages and cultures. Analysis of research data showed that the Persian version of the NOSE questionnaire has acceptable internal consistency, repeatability, convergent validity, and discriminant validity. The Persian version of the NOSE questionnaire has good validity and reliability.

Zirconium-based hydrophobic-MOFs as innovative electrode modifiers for flibanserin determination: Exploring the electrooxidation mechanism using a comprehensive spectroelectrochemical study.

Threedifferent types of Zr-based MOFs derived from benzene dicarboxylic acid (BDC) and naphthalene dicarboxylic acid as organic linkers (ZrBDC, 2,6-ZrNDC, and 1,4-ZrNDC) were synthesized. They were characterized using X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform IR spectroscopy (FT-IR), and Transmission electron microscopy (TEM). Their hydrophilic/hydrophobic nature was investigated via contact angle measurements; ZrBDC MOF was hydrophilic and the other two (ZrNDC) MOFs were hydrophobic. The three MOFs were combined with MWCNTs as electrode modifiers for the determinationof a hydrophobic analyte, flibanserin (FLB), as a proof-of-concept analyte. Under the optimized experimental conditions, a significant enhancement in the oxidation peak current of FLB was observed when utilizing 2,6-ZrNDC and 1,4-ZrNDC, being the highest when using 1,4-ZrNDC. Furthermore, a thorough investigation of the complex oxidation pathway of FLB was performed by carrying out simultaneous spectroelectrochemical measurements. Based on the obtained results, it was verified that the piperazine moiety of FLB is the primary site for electrochemical oxidation. The fabricated sensor based on 1,4-ZrNDC/MW/CPE showed an oxidation peak of FLB at 0.8V vs Ag/AgCl. Moreover, it showed excellent linearity for the determinationof FLB in the range 0.05 to 0.80μmol L-1 with a correlation coefficient (r) = 0.9973 and limit of detection of 3.0nmol L-1. The applicability of the developed approach was demonstrated by determinationof FLB in pharmaceutical tablets and human urine samples with acceptable repeatability (% RSD values were below 1.9% and 2.1%, respectively) and reasonable recovery values (ranged between 97 and 103% for pharmaceutical tablets and between 96 and 102% for human urine samples). The outcomes of the suggested methodology can be utilized for the determinationof other hydrophobic compounds of pharmaceutical or biological interest with the aim of achieving low detection limits of these compounds in various matrices.

Development of a Highly Selective Chloride Ion Potentiometric Sensor Utilizing a Novel N, N-Ethylene-bis-(Salicylideneaminato) Zinc (II) Molecule for Clean Environment

The present study focuses on the advancement of a chloride ion potentiometric sensor that exhibits high selectivity. This sensor employs a novel molecule, namely N, N-Ethylene-bis-(Salicylideneaminato) zinc (II), in order to achieve accurate measurements in the pursuit of maintaining a clean environment. N, N′-Ethylenebis( salicylideneaminato) nickel (II) ionophore has been generated as well as evaluated using analysis of NMR, IR and C, H, N. Subsequently, membranes incorporating the ionophore (I) were developed utilizing poly(vinyl chloride) (PVC) as a matrix, with plasticizing solvent mediators including Dioctyl phthalate (DOP), chloronapthalene (CN), Dibutyl phthalate (DBP), and tri-n-butylphosphate (TBP). Additionally, catalyzed cation discriminator, hexadecyltrimethylammonium bromide (HDTMA) was employed to enhance membrane formation. This sensor performed better than all other variants. Its membrane composition was 5 mg ionophore, 32 mg PVC, 60 mg DBP, and 3 mg HDTMA. Notably, the sensor exhibited an extended operational range of 2.0×10−6 to 1.0×10−1 M, in addition to Nernstian compliance (58.8 mV/Decade) within pH span of 2.3–9.3, and an impressive response time of 19 s. A detection range as low as 1.64×10−6 was attained, indicative of its high sensitivity. Furthermore, the sensor exhibited remarkable selectivity for chloride ions, as confirmed by selectivity coefficient measurements obtained through fixed interference technique (FIM). The sensor demonstrated a satisfactory three-month shelf life and acceptable repeatability. In practical application, the sensor demonstrated effectiveness in quantifying chloride ions in wastewater samples. This work addresses important sustainability issues while contributing to an improved comprehension of the underlying concepts of self-assembled behavior and setting up an option for the generation of efficient sensors with potential uses in photonics and microelectronics.

The electrochemical performances of porous niobium pentoxide with multi-walled carbon nanotubes nanocomposite incorporated with glassy carbon electrode for the sensing of chloramphenicol

Chloramphenicol (CPL), a developing emergence of detection, was selected after sorting out many harmful hazards associated with the nominal dose of medications. Therefore, the detection of CPL is needed to defend the ecosystem. Consequently, this work provides exceptional scrutinization of the CPL reduction process utilizing the electrochemical method by the constructed nanomaterial which is hydrothermally prepared metal oxide such as Niobium Pentoxide (Nb2O5) with the Multi-Walled Carbon Nanotube (MWCNT), which are prepared as a nanocomposite of MWCNT/Nb2O5. Thus, MWCNT/Nb2O5 nanocomposite was drop cast on the surface of a glassy carbon electrode to construct MWCNT/Nb2O5/GCE electrode utilized for the detection of CPL. The MWCNT/Nb2O5/GCE composite was characterized by field emission scanning electron microscopy (FESEM), Brunauer-Emmette-Teller studies (BET), high-resolution transmission electron microscope (HR-TEM), energy dispersion X-ray spectroscopy (EDAX), X-ray photon spectroscopy (XPS) and X-ray diffraction analysis (XRD). Furthermore, the electrochemical performance of the prepared electrode was identified by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) studies, respectively. The electrochemical investigations of the MWCNT/Nb2O5/GCE were conducted at −1.0 V to −0.2 V. The limit of detection (LOD) of the CPL was obtained with very low concentrations of 0.1 μM with a high sensitivity of 0.364 μA μM−1 cm−2 and a wide linear range (0.01–240 μM). Finally, the MWCNT/Nb2O5/GCE electrode performed acceptable repeatability, reproducibility, and stability performance. The prepared MWCNT/Nb2O5/GCE electrodes were utilized for the detection of CPL in milk samples and honey samples with acceptable recoveries.

Development of an Optical Sensor Using a Molecularly Imprinted Polymer as a Selective Extracting Agent for the Direct Quantification of Tartrazine in Real Water Samples.

This study presents a new optical sensor for tartrazine (TAR) quantification developed using a molecularly imprinted polymer (MIP) as the recognition element, with optical fiber serving as the supporting substrate. The fiber surface was functionalized with 3-(trimethoxysilyl)propyl methacrylate (MPS), and the fiber was coated with MIP using the precipitation polymerization method. The analysis of MIP immobilization on the functionalized optical fiber (FF) was conducted through the use of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Experimental parameters, such as contact time and fiber length, were adjusted in order to obtain the highest sensitive response signal for the functionalized optical fiber (FF-MIP). The fiber sensor, FF-MIP, exhibited a relatively higher response signal for tartrazine compared to other interfering dyes. The rapid and total desorption of the analyte from FF-MIP allowed the immediate reemployment of FF-MIP, which also presented an acceptable repeatability for the reflectance signal. The imprinting factors for the studied dyes were between 0.112 and 0.936 in front of TAR, 1.405, and selectivity factors were between 1.501 and 12.545, confirming the sensor selectivity. The FF-MIP sensor was successfully applied for tartrazine quantification in real water samples, where it yielded satisfactory results comparable to those of the HPLC reference method.