Limit Of Quantification Values Research Articles

Sensitive and selective electrochemical sensor for palbociclib, a highly selective CDK4/6 inhibitor, based on molecularly imprinted polymer

In this research, a molecularly imprinted polymer (MIP)-based electrochemical sensor was developed for the first time to determine palbociclib (PLB), an oral, selective Cyclin Dependent Kinase (CDK4 and CDK6) inhibitor used in the treatment of breast cancer. Acrylamide (ACR) was selected as the functional monomer to fabricate the proposed sensor (ACR-PLB-MIP/GCE), and polymerization was performed by photopolymerization. To improve the efficiency of the MIP-based electrode for PLB measurement, several factors, including monomer ratio, removal time, removal agent, and rebinding time, were carefully optimized. Under optimal conditions and using the differential pulse voltammetry (DPV) technique, the limit of detection (LOD) of 1.35 × 10−12 M and the limit of quantification (LOQ) of 4.48 × 10−12 M were calculated for PLB analysis using ACR-PLB-MIP/GCE in standard solution. Application of the ACR-PLB-MIP/GCE sensor to commercial serum samples resulted in LOD and LOQ values of 3.33 × 10−12 M and 1.11 × 10−11 M, respectively. The sensor was also applied to the tablet sample for the detection of PLB and a satisfactory RSD% (0.95) was obtained. The results of interference studies confirmed the high selectivity of the electrode for PLB analysis. These results clearly demonstrated that the molecular imprinting approach for the detection of PLB in the novel sensor system is a highly efficient approach.

Validation of an Analytical Method of 3′,4′,5-Trihydroxy-3-Methoxy-6,7-Methylenedioxyflavone 4′-Glucuronide for Standardization of Spinacia oleracea

Spinach (Spinacia oleracea) is one of the most famous vegetables worldwide, rich in essential metabolites for various health benefits. It is a valuable plant source that has the potential to be a nutraceutical. This study aimed to evaluate the single characteristic marker compound to establish the validation of HPLC-DAD methods applied to the development of a nutraceutical using spinach samples. Six metabolites (1–6) were identified from the spinach samples such as freeze-dried spinach (FDS) and spinach extract concentrate (SEC) by LC-Q-TOF/MS analysis. Among the six metabolites, 3′,4′,5-trihydroxy-3-methoxy-6,7-methylenedioxyflavone 4′-glucuronide (TMG) was selected as a marker compound due to its highest abundance and high selectivity. The specificity, accuracy, linearity, precision, repeatability, limit of detection (LOD), and limit of quantification (LOQ) of TMG in the spinach samples (FDS and SEC) were validated according to AOAC international guideline. The specificity was confirmed by monitoring the well separation of the marker compound from other compounds of spinach samples in the base peak intensity (BPI) and ultraviolet (UV) chromatogram. The calibration curve of TMG (15.625~500 μg/mL) had reasonable linearity (R2 = 0.999) considered with LOD and LOQ values, respectively. Recovery rate of TMG was 93–101% for FDS and 90–95% for SEC. The precision was less than 3 and 6% in the intraday and interday. As a result, the HPLC-DAD validation method of TMG in the spinach samples (FDS and SEC) was first established with AOAC and KFDA regulations for approving functional ingredients in functional foods.

Optimisation of analytical methods for tuberculosis drug detection in wastewater: A multinational study

Wastewater-based epidemiology (WBE) is a robust tool for disease surveillance and monitoring of pharmaceutical consumption. However, monitoring tuberculosis (TB) drug consumption faces challenges due to limited data availability. This study aimed to optimise methods for detecting TB drugs in treated and untreated wastewater from four African countries: South Africa, Nigeria, Kenya, and Cameroon. The limit of detection (LOD) for these drugs ranged from a minimum of 2.20 (±1.02) for rifampicin to a maximum of 2.95 (±0.79) for pyrazinamide. A parallel trend was observed concerning the limit of quantification (LOQ), with rifampicin reporting the lowest average LOQ of 7.33 (±3.44) and pyrazinamide showing the highest average LOQ of 9.81 (±2.64). The variance in LOD and LOQ values could be attributed to factors such as drug polarity. Erythromycin and rifampicin exhibited moderately polar LogP values (2.6 and 2.95), indicating higher lipid affinity and lower water affinity.Conversely, ethambutol, pyrazinamide, and isoniazid displayed polar LogP values (−0.059, −0.6, and −0.7), suggesting lower lipid affinity and greater water affinity. The study revealed that storing wastewater samples for up to 5 days did not result in significant drug concentration loss, with concentration reduction remaining below 1 log throughout the storage period. Application of the optimised method for drug detection and quantification in both treated and untreated wastewater unveiled varied results. Detection frequencies varied among drugs, with ethambutol consistently most detected, while pyrazinamide and isoniazid were least detected in wastewater from only two countries. Most untreated wastewater samples had undetectable drug concentrations, ranging from 1.21 ng/mL for erythromycin to 54.61 ng/mL for isoniazid. This variability may suggest differences in drug consumption within connected communities. In treated wastewater samples, detectable drug concentrations ranged from 1.27 ng/mL for isoniazid to 10.20 ng/mL for ethambutol. Wastewater treatment plants exhibited variable removal efficiencies for different drugs, emphasising the need for further optimisation. Detecting these drugs in treated wastewater suggests potential surface water contamination and subsequent risks of human exposure, underscoring continued research's importance.

Wearable, disposable and non-enzymatic fluorescence nanosensor for monitoring sweat glucose through smartphone

The promise of non-invasive health monitoring has fuelled the development of wearable biosensors for in situ detection of biological analytes in sweat. This paper presents a new fluorescent nanosensor probe based on boric acid functionalized and heteroatom doped carbon quantum dots (CQDs) embedded in paper-based analytical devices and integrated with a hydrophilic cotton thread-based microfluidic channel for the development of a flexible, wearable, biocompatible, and biodegradable sweat sensor for real-time measurement of sweat glucose concentration via smartphone readout. The morphological, physiochemical, compositional, crystallinity, and optical properties of nanosensors were extensively investigated. CQD particle sizes were found to be widely dispersed, ranging from 2.6 to 7.1 nm, with an average diameter of 4.38 nm. A dual response via fluorescence and colorimetric change was demonstrated for on-site sweat glucose monitoring using a smartphone camera to capture images in RGB (red, green, and blue) format and analyse them simultaneously by a customized android app, with quantitative results displayed on the smartphone. The limit of detection value for in situ measurement of sweat glucose concentration was 1.40 to 2.00 μM (25.25 to 36.13 μg/dL) and the limit of quantification value was 4.67 to 6.69 μM (84.16–120.44 μg/dL) in the pH range of 4.5 to 7.5. The developed sensor's performance metrics were validated using a standard clinical technique, which indicates strong correlation between two methods with Pearson correlation coefficient values of 0.83 and 0.80 for non-diabetic and type- II diabetes patients, respectively. Besides, interference, spike, and recovery studies were carried out with recovery rates ranging from 96.5 to 105.8 %, demonstrating good repeatability and reproducibility. Furthermore, feasible fluorescence quenching processes have been explored. In addition, the disposable and biodegradable nature of the nanosensor probe was studied by throwing it into the soil in the natural environment, where it dissolves almost spontaneously after three weeks.

DEVELOPMENT OF A FAST LIQUID CHROMATOGRAPHY METHOD WITH A CHEMOMETRIC APPROACH BASED ON BOX-BEHNKEN DESIGN FOR THE DETERMINATION OF ANTIDEPRESSANTS IN PHARMACEUTICAL FORMULATIONS

Objective: The objective of this work was to develop a liquid chromatographic method for the quantification of antidepressants, namely duloxetine (DXN), fluoxetine (FXN), citalopram (CIT), paroxetine (PXN), and sertraline (SRN), by a chemometric approach based on Box-Behnken design. Material and Method: After initial experiments to determine significant parameters, a Box-Behnken design consisting of 17 experiment sets was carried out. All separations were conducted using an Agilent Poroshell 120 EC-C18 analytical column (75 mm × 4.6 mm × 2.7 µm). Result and Discussion: The optimum levels of pH, acetonitrile ratio, and flow rate were determined with the desirability function as 2.7, 38%, and 1.1 ml/min, respectively. The differences (<8%) between predicted optimum responses and experimentally obtained results proved the model's suitability. Limits of detection and limits of quantification values were in the ranges of 0.17-0.29 µg/ml and 0.53-0.89 µg/ml, respectively. The feasibility of the technique was proven by analyzing PXN and DXN formulations.

There's Something in What We Eat: An Overview on the Extraction Techniques and Chromatographic Analysis for PFAS Identification in Agri-Food Products.

Per- and polyfluorinated alkyl substances (PFASs) are a group of anthropogenic chemicals used in a range of industrial processes and consumer products. Recently, their ubiquitous presence in the environment as well as their toxicological effects in humans have gained relevant attention. Although the occurrence of PFASs is widely investigated in scientific community, the standardization of analytical method for all matrices still remains an important issue. In this review, we discussed extraction and detection methods in depth to evaluate the best procedures of PFAS identification in terms of analytical parameters (e.g., limits of detection (LODs), limits of quantification (LOQs), recoveries). Extraction approaches based on liquid-liquid extraction (LLE), alkaline digestion, and solid phase extraction (SPE), followed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analysis are the main analytical methods applied in the literature. The results showed detectable recoveries of PFOA and PFOS in meat, milk, vegetables, eggs products (90.6-101.2% and of 89.2-98.4%), and fish (96-108%). Furthermore, the low LOD and LOQ values obtained for meat (0.00592-0.01907 ng g-1; 0.050 ng g-1), milk (0.003-0.009 ng g-1; 0.010-0.027 ng g-1), fruit (0.002-0.009 ng g-1; 0.006-0.024 ng g-1), and fish (0.00369-0.017.33 ng g-1; 0.05 ng g-1) also confirmed the effectiveness of the recent quick, easy, cheap, effective, rugged, and safe method (QuEChERS) for simple, speedy, and sensitive ultra-trace PFAS analysis.

Reduced Schiff base as novel two-faced sensor for the detection of iron(III) and carbonate ions

The reduced Schiff base–naphthalene-2-ol (RSB) can be utilized as multifunctional probe to detect both Fe3+ and CO32–. The complexation was formed through coordinate covalent bond between Fe3+ and RSB, and through hydrogen bond between CO32– and RSB. The characterizations were investigated by UV–visible spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy and confirmed by density functional theory (DFT) calculation. The quenching mechanism of RSB with Fe3+ and CO32– were described through inner filter effect (IFE) and static quenching (SQ), respectively. Furthermore, the quenching of RSB was correlated to the concentrations of Fe3+ (R2 = 0.9966) and CO32– (R2 = 0.9954) within a linear range of 1 – 50 ppm. The limit of detection (LOD) and limit of quantification (LOQ) for Fe3+ were determined as 0.75 ppm and 2.52 ppm, respectively. Meanwhile, for CO32–, the LOD and LOQ were 0.27 ppm and 2.73 ppm, respectively. Finally, we demonstrate the application of RSB which can be easily synthesized and obtained with high yield to samples containing Fe3+ and CO32– with concentrations correlated to LOD and LOQ values.

Sensitivity of chitosan/reduced graphene oxide/manganese dioxide modified electrodes for cholesterol detection using cyclic voltammetry

Cholesterol detection needs to be carried out to detect early symptoms of dangerous diseases such as heart disease. The process of detecting cholesterol in the human blood requires a sensitive detection tool in order to produce accurate values. This paper reports the performance of chitosan thin films modified with reduced graphene oxide (rGO) and manganese dioxide (MnO2) as the sensitive layer of working electrodes in detecting cholesterol. The electrode substrate is a copper-screen printed electrode (copper-SPE) which was patterned into 5 mm of sensitive area. The chitosan and chitosan-reduced graphene oxide (rGO) matrices were deposited on the top of working electrodes. The characterization of chitosan, chitosan/rGO, and chitosan/rGO/MnO2 thin films was performed using AFM, FE-SEM, and FTIR. The electrochemical sensing properties of modified working electrode were observed using an electrochemical method of cyclic voltammetry (CV). The novelty of this research is the utilization of chitosan/rGO/MnO2 thin film-based working electrode for detecting cholesterol. The testing results indicated that the sensitivity of the modified working electrodes increased when working electrodes based on chitosan/rGO/MnO2 thin film were used for cholesterol detection compared to the working electrodes based on the chitosan thin film. It was proven from the sensitivity of working electrodes based on chitosan/rGO/MnO2 thin film which gave the lowest value of 3.21 × 10−5 µA/µM as well as the ability of working electrodes based on chitosan/rGO/MnO2 thin film which worked at limit of detection (LoD) 0.26 µM/L and limit of quantification (LoQ) 0.87 µM/L. Based on the sensitivity, LoD, and LoQ values, the chitosan/rGO/MnO2 modified electrodes can be used as working electrodes to measure cholesterol concentration in blood.

Sensitive Determination of Hydrochlorothiazide Drug in the Various Samples Via Developed Method of CFIA System

Hydrochlorothiazide drug determination in pharmaceutical and biological urine samples using a novel continuous flow-injection analysis technique that is rapid, simple, economical, and sensitive. The complex formed by the reaction of hydrochlorothiazide and O-phenylenediamine with potassium ferricyanide to produce an orange-colored product at 480 nm was the basis for the proposed method. Other chemical and physical parameters that affect the stability and development of the colored product used in this developed method includes sample volume, flow rate, reagent concentrations, and reaction coil. The proposed method’s linearity ranges from 5 to 150 μg.mL-1 and its correlation coefficients were 0.9988, and the recovery percentage and error percentage were 100.88 and 0.88, respectively. The detection limit and Limit of quantification values were 2.622 and 7.97. A sample throughput of 90 samples. hour1- . The new approach was effectively employed to determine the presence of hydrochlorothiazide in the pure, biological, and pharmaceutical samples.

Distribution of Pesticides and Polychlorinated Biphenyls in Food of Animal Origin in Croatia.

Pesticides and polychlorinated biphenyls (PCBs) are persistent environmental pollutants. When entering the food chain, they can represent a public health problem due to their negative effects on health. In this study, concentrations of organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), pyrethroids, carbamates, and PCBs-a total 73 compounds-were determined in a total of 2268 samples of fat tissues (beef, pork, sheep, goat, poultry, game, horse, rabbit) and processed fat, meat, and processed meat products collected in Croatia during an 8-year period. In fatty tissues, 787 results exceeded the limits of quantification (LOQ): 16 OCPs, eight OPPs, six pyrethroids, one carbamate, and seven PCBs. The most positive results in fat samples were found for OCPs, with a frequency of quantification in the range of 57.5-87.5%. Hexachlorobenzene (HCB) and dichlorodiphenyldichloroethylene (DDE) were quantified in the highest percentages, in the ranges of 5.5-66.7% and 5.4-55.8%. Concentrations above the MRL values were determined for chlorpyrifos in pork fat and for resmethrin in six fat samples and one pâté. In 984 samples of meat and meat products, only 62 results exceeded the LOQ values. The highest frequency of quantification was determined for OCPs (25 samples), of which 40% were DDT isomers (60% DDE). Frequency quantifications of PCBs in fat samples were between 7.23 and 36.7%. An evaluation of the health risk assessment showed that the consumption of fat, meat, and meat products does not pose a threat to consumer health, since all EDI values were well below the respective toxicological reference values.

Efficient pre-concentration of trace levels of the synthetic food dye in foodstuff samples through an adsorption extraction technique using a novel inorganic–organic nanocomposite

In the present study, a maleic acid-functionalized exfoliated graphite/calcium hydroxide (MA-EG/Ca(OH)2) was constructed and employed as a novel inorganic–organic nanocomposite for an efficient dispersive solid-phase microextraction (DSPME) of trace levels of sunset yellow (SY), a synthetic food dye in foodstuff samples before UV–Vis determination. To identify and characterize of the sorbent, various analytical techniques were utilized, including, Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), and Brunauer-Emmett-Teller (BET) analyses. The MA-EG/Ca(OH)2 exhibited a specific surface area of 40.35 m2 g−1 and adsorption capacity of 46.72 mg g−1 towards SY. Central composite design (CCD) in conjunction with a response surface methodology (RSM)-based ANOVA analysis was applied for evaluation and optimization of effective factors including pH (X1), sorbent mass (X2), contact time (X3), and elution volume (X4). According to the results, the optimum values were pH: 6.0, sorbent mass: 12 mg, contact time: 12 min, and elution volume: 0.18 µL. Under theses optimized conditions, DSPME/UV–Vis determination demonstrated a linear range of 50–4800 ng mL−1, a limit of detection (LOD) of 12.45 ng mL−1, and a limit of quantification (LOQ) of 41.49 ng mL−1 (n = 3). The relative standard deviation (RSD) at low concentration level (50–500 ng mL−1) of SY was 4.58 %. Recovery values in different concentration levels were in the range of 96.4–102.9 %. Overall, the proposed method showed the superior features, including ease of synthesizing the sorbent, acceptable LOD and LOQ values, remarkable sensitivity, a wide operational range, good reusability (up to five cycles), environmentally friendly as well as cost-effectiveness, that make it a promising candidate for the analysis of SY in foodstuff samples.

Development of a Nanoplate-Based Digital PCR Test Method for Quantitative Detection of Human Adenovirus DNA.

Digital polymerase chain reaction (dPCR) assay is an advanced PCR technique that allows for the simultaneous detection and absolute quantification of diverse pathogens.Commercially validated kits available for detecting all subtypes of human adenovirus (HAdV) are limited. This study aimed to demonstrate the development of an in-house nanoplate-based dPCR assay with high sensitivity, even at low copy numbers. In this methodological study, the standardized HAdV DNA was prepared by amplifying the specific hexon gene region with real-time PCR and purifying the HAdV DNA using magnetic beads from HAdV-positive extractions. Dilutions were tested in triplicate during three independent runs to determine the dynamic range, the limit of detection (LoD), the limit of quantification (LoQ), precision, and reproducibility. The primer and probe sequences used in the study were selected based on a literature review to ensure the detection of all HAdV serotypes in a single run. The selected primers were verified using the US National Center for Biotechnology Information (NBCI) nBLAST tools, and the target sequence was determined using the BioEdit software. The DNA concentration of the stock solution was measured using a Qubit fluorometer. The estimated copy number of the stock solution per milliliter was calculated based on the length of the amplified base sequence and fluorometer measurement. The dynamic range of the test was determined to be from 770.4 to 0.9476 cp/μl, with the LoD and LoQ values both being 0.9476 cp/μl. The coefficient of determination (r 2) value of the test was 0.9986. The results demonstrated that the dPCR method could be an ideal tool for the diagnosis and absolute quantification of human adenoviruses, especially in low copy numbers. In order to determine the reproducibility of the test and validate the method for field use, it needs to be developed and adapted in various laboratories and supported by clinical studies.

Fenpicoxamid-Imprinted Surface Plasmon Resonance (SPR) Sensor Based on Sulfur-Doped Graphitic Carbon Nitride and Its Application to Rice Samples.

This research attempt involved the development and utilization of a newly designed surface plasmon resonance (SPR) sensor which incorporated sulfur-doped graphitic carbon nitride (S-g-C3N4) as the molecular imprinting material. The primary objective was to employ this sensor for the quantitative analysis of Fenpicoxamid (FEN) in rice samples. The synthesis of S-g-C3N4 with excellent purity was achieved using the thermal poly-condensation approach, which adheres to the principles of green chemistry. Afterwards, UV polymerization was utilized to fabricate a surface plasmon resonance (SPR) chip imprinted with FEN, employing S-g-C3N4 as the substrate material. This process involved the inclusion of N,N'-azobisisobutyronitrile (AIBN) as the initiator, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, methacryloylamidoglutamic acid (MAGA) as the monomer, and FEN as the analyte. After successful structural analysis investigations on a surface plasmon resonance (SPR) chip utilizing S-g-C3N4, which was imprinted with FEN, a comprehensive investigation was conducted using spectroscopic, microscopic, and electrochemical techniques. Subsequently, the kinetic analysis applications, namely the determination of the limit of quantification (LOQ) and the limit of detection (LOD), were carried out. For analytical results, the linearity of the FEN-imprinted SPR chip based on S-g-C3N4 was determined as 1.0-10.0 ng L-1 FEN, and LOQ and LOD values were obtained as 1.0 ng L-1 and 0.30 ng L-1, respectively. Finally, the prepared SPR sensor's high selectivity, repeatability, reproducibility, and stability will ensure safe food consumption worldwide.

Certified reference material (CRM) of tea powder (BARC - D3201) for K, Ca, P, Mg, Mn, Al, Fe, Ba, Zn, Cu, Sr, Pb, As, Cd, and Hg: Method validation and its production

A certified reference material (CRM) for major and trace elements in black tea powder has been developed at National Centre for Compositional Characterization of Materials/Bhabha Atomic Research Centre (BARC), Hyderabad. The study describes an acid assisted microwave digestion of tea powder followed by quantitation of K, Ca, P, Mg, Mn, Al, Fe, Ba, Zn, Cu and Sr by ICP-AES; Pb, Cd by GFAAS and As, Hg by AFS in the digests. The method was validated in terms of selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), trueness, precision, traceability, ruggedness and combined uncertainty using a CRM of tea powder (NMIJ CRM 7505-a) and spike recovery studies. The obtained values of LOQ ranged from 0.018 % m/m for Ca to 0.35mg kg−1 for Hg. Precision of the method was found to be <5% for all the analytes (K, Ca, P, Mg, Mn, Al, Fe, Ba, Zn, Cu, Sr, Cd and Hg) excepting for Pb and As (6.5 % at 95% confidence level). The obtained LOQ values, trueness and precision established that the validated method could be used for the characterization of candidate tea CRM during homogeneity and stability studies. Candidate tea CRM (∼3.6 Kg) was processed (which included spiking, drying grinding and sieving) and its homogeneity was assessed at various levels with respect to all 15 property values. The assignment of the property values for each element was carried out after an interlaboratory comparison exercise (ILCE), where 11 laboratories from various government and private sectors participated. A total of four techniques inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES), graphite-furnace atomic-absorption spectrometry (GFAAS) and atomic-fluorescence spectrometry (AFS) were used during ILCE. Property values were assigned for 14 elements (K, Ca, P, Mg, Mn, Al, Fe, Ba, Zn, Cu, Sr, Pb, Cd, and Hg) along with combined uncertainties. The concentration with expanded uncertainties of the property values were between 0.458 ± 0.025 for Ca (% m/m) to 0.60 ± 0.084 mg kg−1 for Hg. Long-term stability studies suggested that the produced tea CRM is stable at storage temperature (4 °C) for the last two years, whereas, short-term stability studies (at temperatures 4, 25 and 40 °C) established its transportation stability at tested temperatures for a period of three weeks. Preparation and certification of tea CRM (BARC-D3201) was carried out in accordance with ISO Guides 17034 and 35.

Magnetic Hydrogel Beads as a Reusable Adsorbent for Highly Efficient and Rapid Removal of Aluminum: Characterization, Response Surface Methodology Optimization, and Evaluation of Isotherms, Kinetics, and Thermodynamic Studies.

Biopolymers such as alginate and gelatin have attracted much attention because of their exceptional adsorption properties and biocompatibility. The magnetic hydrogel beads produced and used in this study had a core structure composed of magnetite nanoparticles and gelatin and a shell structure composed of alginate. The combination of the metal-ion binding ability of alginate and the mechanical strength of gelatin in magnetic hydrogel beads presents a new approach for the removal of metal from water sources. The beads were designed for aluminum removal and fully characterized using various methods, including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, microcomputed tomography, and dynamic mechanical analysis. Statistical experimental designs were employed to optimize the parameters of the adsorption and recovery processes. Plackett-Burman Design, Box-Behnken Design, and Central Composite Design were used for identifying the significant factors and optimizing the parameters of the adsorption and recovery processes, respectively. The optimum parameters determined for adsorption are as follows: pH: 4, contact time: 30 min, adsorbent amount: 600 mg; recovery time: reagent 1 M HNO3; and contact time: 40 min. The adsorption process was described by using the Langmuir isotherm model. It reveals a homogeneous bead surface and monolayer adsorption with an adsorption capacity of 5.25 mg g-1. Limit of detection and limit of quantification values were calculated as 4.3 and 14 μg L-1, respectively. The adsorption process was described by a pseudo-second-order kinetic model, which assumes that chemisorption is the rate-controlling mechanism. Thermodynamic studies indicate that adsorption is spontaneous and endothermic. The adsorbent was reusable for 10 successive adsorption-desorption cycles with a quantitative adsorption of 98.2% ± 0.3% and a recovery of 99.4% ± 2.6%. The minimum adsorbent dose was determined as 30 g L-1 to achieve quantitative adsorption of aluminum. The effects of the inorganic ions were also investigated. The proposed method was applied to tap water and carboy water samples, and the results indicate that magnetic hydrogel beads can be an effective and reusable bioadsorbent for the detection and removal of aluminum in water samples. The recovery values obtained by using the developed method were quantitative and consistent with the results obtained from the inductively coupled plasma optical emission spectrometer.

Activated carbon synthesized from Arecanut catechu L. as a sustainable precursor intercalated TiO2 modified electrode for the detection of fungicide Dichlorophen

Pesticides, such as dichlorophen (DCP), pose serious threats to the ecosystem and human health. Hence, developing an efficient and sensitive detection method is crucial for environmental monitoring and remediation. In this study, we present a novel composite material comprised of TiO2 intercalated areca nut husk-derived activated carbon for the ultrasensitive detection of dichlorophen. The activated carbon is derived through a well-established activation process using areca nut husk waste, a sustainable biomass material. The material's irregular structure and large surface area provide abundant adsorption sites for the target analyte, DCP. The integration of TiO2 nanoparticles further enhances the detection capability due to their exceptional catalytic properties. Upon exposure to DCP, their interaction with the surface of composite material leads to measurable changes in its electrical and chemical properties. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques are used to validate the performance of the fabricated electrode. The developed ultrasensitive detection method exhibits remarkable DL (detection limit, 1.01 × 10−8 M) and QL (quantification limit, 3.36 × 10−8 M) values, hence can be a promising alternative for environmental monitoring, industrial safety, and public health applications. The synergistic effect between activated carbon and TiO2 nanoparticles ensures a highly sensitive and selective response to DCP. Consequently, this advanced sensor system has great potential for detecting and quantifying dichlorophen concentrations in diverse environmental samples.

Electrochemical biosensing based comparative study of monoclonal antibodies against SARS-CoV-2 nucleocapsid protein

In this study, we are reporting an electrochemical biosensor for the determination of three different clones of monoclonal antibodies (mAbs) against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recombinant nucleocapsid protein (rN). The nucleocapsid protein was chosen as a system component identifying and discriminating antibodies that occur after virus infection instead of S protein used in serological tests to measure antibodies raised after vaccination and infection. The sensing platform was based on a screen-printed carbon electrode (SPCE) covered with gold nanoparticles (AuNP) and subsequently modified with a self-assembled monolayer (SAM) to ensure the covalent immobilization of the rN. The interaction between the protein and three clones of mAbs against SARS-CoV-2 rN with clone numbers 4G6, 7F10, and 1A6, were electrochemically registered in the range of concentrations. Three techniques, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and pulse amperometric detection (PAD) were used for the detection. A gradual change in the responses with an increase in mAbs concentration for all techniques was observed. To assess the performance of the developed electrochemical biosensor, ‘complexation constant’ (KC), limit of detection (LOD), and limit of quantification (LOQ) were calculated for all assessed clones of mAbs and all used techniques. Our results indicated that DPV possessing higher fitting accuracy illustrated more significant differences in KC constants and LOD/LOQ values. According to the DPV results, 7F10 clone was characterized with the highest KC value of 1.47 ± 0.07 μg/mL while the lowest LOD and LOQ values belonged to the 4G6 clone and equaled 0.08 ± 0.01 and 0.25 ± 0.01 μg/mL, respectively. Overall, these results demonstrate the potential of electrochemical techniques for the detection and distinguishing of different clones of mAbs against SARS-CoV-2 nucleocapsid protein.

Dissipation kinetics, decontamination, consumer risk assessment and monitoring of flonicamid and imidacloprid residues in capsicum under open field and polyhouse condition.

Liquid chromatography mass spectrometry (LC-MS)-based detection of flonicamid, imidacloprid and 6-chloronicotinic acid residues was validated and analysed in capsicum fruit, processed products and soil. The standard concentrations (0.0025 to 0.25 μg mL-1) of insecticides had a good linear curve (r2>0.99). Limit of detection and limit of quantification values were 0.0025 and 0.01 mg kg-1, respectively. The accuracy (80.53 to 100.33 %) of capsicum matrices and soil (89.41 to 100.52 %) and precision (RSD <10%) were established. Dissipation of imidacloprid (20 and 40 g a.i. ha-1) and flonicamid (75 and 150 g a.i. ha-1) at single (X) and double dose (2X) was studied under open field and polyhouse conditions. Under open field conditions, the flonicamid and imidacloprid residues persisted with half-life of 1.98, 2.90 days (X) and 2.80, 3.14 (2X) days, respectively. While under polyhouse conditions, the flonicamid and imidacloprid residues persisted with a half-life of 2.84, 3.66 (X) and 3.24, 3.97 (2X) days, respectively. The metabolite, 6-CNA, was not detected in any samples under open field and polyhouse condition. Among decontamination treatments, cooking in boiling water for 10 minutes reduced 78 to 81.60 percent of imidacloprid and flonicamid residues in both doses. The estimated dietary risk assessment of imidacloprid and flonicamid residues (RQ <1) indicated that the risk is within the acceptable limit. In farmgate capsicum samples, residues of flonicamid (7 samples) and imidacloprid (11 samples) were detected. Market samples of capsicum products (powder, flakes and sauce) were not detected with residues of selected insecticides.

A Novel Approach of CFIA Technique for Assaying of Furosemide (Sulfa Drug) as Antibacterial Agent in Pharmaceutical and Biological Samples Using Potassium Ferricyanide as Oxidizing Agent

Furosemide drug determination in pharmaceutical and biological urine samples using a novel continuous flow-injection analysis technique that is simple, rapid, sensitive and economical. The complex formed by the reaction of furosemide and O-phenylenediamine with oxidative agent K3[Fe(CN)6] to produce an orange-yellow colored product at 460 nm was the basis for the proposed method. The proposed method’s linearity ranges (3-100) μg.mL-1and (1-50) μg.mL-1 for CFIA/merging zone methods and batch .The detection limit and Limit of quantification values were 2.7502 μg.mL-1 and 9.1697 μg.mL-1 the relative standard deviation was 0.7143 %, and the average recovery is 98.80% with a verified sample throughput of 73 h-1 . The new approach was effectively employed to determination of furosemide the presence of in the pure, biological, and pharmaceutical samples.

Utilization of green ATR-FTIR spectroscopic method for quantitative analysis of Ibuprofen tablets

Aim: The aim of this study is to propose a green and nondestructive method using the ATR-FTIR method for the quantitative analysis of Ibuprofen tablet dosage forms. Herein, the technique has been validated as an alternative green tool that evades necessary sample preparation procedures required in traditional quantitative methods. Methods: The method depends on selecting CO of the Ibuprofen stretching band in the range 1620–1750 cm-1 to quantitatively determine Ibuprofen in original samples. The pack area (AUC) from ATR-FTIR spectral scanning of samples has been determined through the first derivative measurements. Results: The assay results indicated that no interferences between the excipients or additives and the active ingredients of the commercial tablets interferences. The linearity is excellent within the concentration range of 0.2 to 1.5 w/w % (r = 0.9994). A percentage of recoveries ranged between 99.7–10.5 which are in good agreement with the pharmacopeial percent recovery standards. The high degree of sensitivity of the technique was demonstrated by obtaining a 0.028 w/w % detection limit and a 0.1599 w/w % limit of quantification values.