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This study centers on the development and characterization of an innovative electrochemical sensing probe composed of a sensing mesoporous functional sol–gel coating integrated onto a glassy carbon electrode (sol–gel/GCE) for the detection of NH3 and/or NH4+ in water. The main interest for integrating a functional sol–gel coating onto a GCE is to increase the selective and sensing properties of the GCE probe towards NH3 and/or NH4+ ions. The structure and surface morphology of the newly developed sol–gel/GCE probe were characterized employing scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and Fourier-transform infrared (FTIR), while the electrochemical sensing properties were evaluated by Berthelot's reaction, cyclic voltammetry (CV), and adsorptive square wave–anodic striping voltammetry (Ads SW–ASV). It is shown that the newly developed sol–gel coating is homogeneously deposited on the GCE with a sub-micron and uniform thickness close to 630 nm and a surface roughness of 25 nm. The sensing testing of the sol–gel/GCE probe showed limits of detection and limits of quantitation of 1.7 and 5.56 nM of NH4+, respectively, as well as a probe sensitivity of 5.74 × 10−1 μA/μM cm−2. The developed probe was fruitfully validated for the selective detection of NH3/NH4+ in fresh and sea water samples. Computed Student texp (0.45–1.25) and Fexp (1.69–1.78) (n = 5) tests were less than the theoretical ttab (2.78) and Ftab (6.39) at 95% probability. [ABSTRACT FROM AUTHOR]

The current study reports on the impact of a series of functional alkoxysilanes on the wettability and structure of a well-established silicon/zirconium hybrid anticorrosion sol–gel coating. The selected functional alkoxysilanes comprise tetra ethylorthosilicate (TEOS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), 3-aminopropyltriethoxysilane (APTES) and vinyltriethoxysilane (VTES) and are incorporated at various concentrations (1, 5, 10 and 20%) within the silicon/zirconium sol–gel material. The prepared materials are successfully processed as coatings and cured at different temperatures in the range of 100–150 °C. The characterisation of the structures and surfaces is performed by dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), silicon nuclear magnetic resonance spectroscopy (29Si-NMR), atomic force microscopy (AFM) and static water contact angle (WCA). Structural characterisations (DLS, FTIR,29Si-NMR) show that the functional alkoxysilanes effectively bind at the surface of the reference sol–gel material, resulting in the formation of functional core–shell nanoparticles. WCA results show that the hydrophobic properties of all materials decrease with curing temperature, and AFM analysis demonstrated that this behaviour is associated with a decrease in roughness. The physico-chemical processes taking place are critically assigned and discussed. [ABSTRACT FROM AUTHOR]

The evolution in foodstuff-monitoring processes has increased the number of studies on biogenic amines (BAs), in recent years. This trend with future perspective needs to be assembled to address the associated health risks. Thus, this study aims to cover three main aspects of BAs: (i) occurrence, physiology, and toxicological effects, most probable formation mechanisms and factors controlling their growth; (ii) recent advances, strategies for determination, preconcentration steps, model technique, and nature of the matrix; and (iii) milestone, limitations with existing methodologies, future trends, and detailed expected developments for clinical use and on-site ultra-trace determination. The core of the ongoing review will discuss recent trends in pre-concentration toward miniaturization, automation, and possible coupling with electrochemical techniques, surface-enhanced Raman scattering, spectrofluorimetry, and lateral flow protocols to be exploited for the development of rapid, facile, and sensitive on-site determination strategies for BAs. [ABSTRACT FROM AUTHOR]

The study reports a simple and highly selective spectrofluorometric method for trace determination and speciation of chromium(iii & vi) species in water using 10-(3-dimethylaminopropyl) phenothiazine hydrochloride, namely, promazine hydrochloride (PMH) as a fluorescence tagging reagent. The method is based on the redox reaction between PMH and chromium(vi) in aqueous H3PO4, resulting in the formation of complex [Cr(iii)–PMH] followed by fluorescence quenching at λex/em = 300/449 nm. An exceptional value for the limit of detection (LOD = 0.03 μg L−1) is attained with a linear range of 0.1–1.0 μg L−1 under the optimized conditions. A coefficient of variation (CV) of ±2.05% (n = 5) is obtained at 2.0 μg L−1 level of chromium(vi). Chemical speciation of the chromium(iii & vi) species is successfully accomplished after the oxidation of chromium(iii) to chromium(vi) with H2O2 in KOH solution at pH 9.0. The method is validated in environmental water samples with satisfactory recovery percentages (＞97.7%) using inductively coupled plasma-optical emission spectrometry (ICP-OES). The proposed and reference methods are subjected to statistical treatment (student's t and F tests) at 95% confidence with no significant difference, indicating the precision and accuracy of the proposed optical probe. [ABSTRACT FROM AUTHOR]

Porous carbons were prepared by carbonization and activation of phenol formaldehyde resin by gasification with CO at 900 °C. Prepared activated carbon from phenol formaldehyde was characterized by measuring thermogravimetry (TG), differential thermal analysis (DTA), pH, surface area, porosity, and pore size distribution. The specific surface area (SSA) of these carbons ranges from 562 to 1904 m/g, while their point of zero charge (pHPZC) varies from 2.6 to 8.8. The ability of the prepared activated carbon by gasification with CO at 900 °C from phenol formaldehyde resin (PFAC) to remove a series of polycyclic aromatic hydrocarbons (PAHs), e.g., naphthalene, fluorene, phenanthrene, pyrene, and fluoranthene, from mixtures of organic solvents with different polarities and chemical structures was tested. The adsorption capacity increases with the increasing the SSA and pHPZC of the carbons, confirming the roles of dispersive interactions. The kinetics and thermodynamics of the adsorption of phenanthrene as a model compound of PAH on PFAC in the organic solvent were studied. The adsorption capacity became notably greater with an increase in contact time and initial phenanthrene concentration. [ABSTRACT FROM AUTHOR]

There is growing demand for separation of 90 Y carrier free from 90 Sr coexisting to produce high purity 90 Y essential for radiopharmaceutical uses. Thus, in this context the sorption profiles of Y 3+ and Sr 2+ from aqueous solutions containing diethylenetriaminepenta acetic acid (DTPA), ethylenediaminetetra-acetic acid (EDTA), acetic acid, citric acid, or NaCl onto Chelex-100 (anion ion exchange) solid sorbent were critically studied for developing an efficient and low-cost methodology for selective separation of Y 3+ from Sr 2+ ions (1.0 × 10 -5  M). Batch experiments displayed relative chemical extraction percentage (98 ± 5.4%) of Y 3+ from aqueous acetic acid solution onto Chelex-100 (anion ion exchanger), whereas Sr 2+ species showed no sorption. Hence, a selective separation of Y 3+ from its parent 90 Sr 2+ has been established based upon percolation of the aqueous solution of Y 3+ and Sr 2+ ions containing acetic acid at pH 1-2 through Chelex-100 sorbent packed column at a 2 mL min -1 flow rate. Y 3+ species were retained quantitatively while Sr 2+ ions were not sorbed and passed through the sorbent packed column without extraction. The sorbed Y 3+ species were then recovered from the sorbent packed column with HNO 3 (1.0 M) at a 1.0 mL min -1 flow rate. A dual extraction mechanism comprising absorption associated to "weak-base anion exchanger" and "solvent extraction" of Y 3+ as (YCl 6 ) 3- and an extra part for "surface adsorption" of Y 3+ by the sorbent is proposed. The established method was validated by measuring the radiochemical (99.2 ± 2 1%), radionuclide purity and retardation factor ( R f  = 10.0 ± 0.1 cm) of 90 Y 3+ recovered in the eluate. Ultimately, the sorbent packed column also presented high stability for reusing 2-3 cycles without drop in its efficiency (±5%) towards Y 3+ uptake and relative chemical recovery. A proposed flow sheet describing the analytical procedures for the separation of 90 Y 3+ from 90 Sr 2+ using chelating Chelex 100 (anion exchange) packed column is also included., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2024 Mohammad S. El-Shahawi et al.)

Spectral interference through the presence of uninformative variables, excess reagents, and complications in the refinement of the analyte signal is common in the quest to identify complex species in real samples. Therefore, an economical green, facile, and sensitive strategy has been developed for Cu 2+ detection using the anionic surfactant sodium dodecylsulphate- (SDS-) assisted dual-wavelength β -correction spectrophotometric strategy combined with the chromogenic reagent zincon (ZI). The low limits of detection (LOD) and quantification (LOQ) of Cu 2+ using ordinary (single wavelength) spectrophotometry were 0.19 (3.02) and 0.63 (10.0)  μ gmL -1 , and these values were improved to 0.08 (1.27) and 0.26  μ gmL -1 (4.12  μ M)) using β -correction (dual wavelength) spectrophotometry, respectively. The LOD and LOQ were improved from 0.08 (1.27) and 0.26 (4.12)  μ gmL -1 to 0.02 (0.32) and 0.08  μ gmL -1 (1.27  μ M) using SDS-assisted dual- β -correction spectrometry, respectively. Ringbom, s , and the corrected absorbance ( A c ) versus Cu 2+ concentration plots were linear over the concentration range 1.10-2.4 (17.4-38.1) and 0.50-2.40  μ gmL -1 (7.94-38.1  μ M), respectively. Sandell's sensitivity index of 3.0 × 10 -3   μ g/cm 2 was achieved. The selectivity was further confirmed via monitoring the impact of common diverse ions and surfactants on the corrected absorbance. Total determination and Cu 2+ speciation in water were favorably implemented and validated by ICP-OES at 95% ( P =0.05). Satisfactory Cu 2+ recoveries in tap (92.2-98.0%) and mineral (105-111.0%) water samples were achieved. The sensing system is simple, reliable, sensitive, and selective for Cu 2+ detection., Competing Interests: The authors declare that there are no conflicts of interest., (Copyright © 2023 Hassan Alwael et al.)

The extraordinary prerequisite for the analysis of an anabolic steroid, namely dianabol (DB), has inspired towards the development of a cost-effective and high-performance sensing probe. Thus, a simple and robust electrochemical sensor (c-MWCNTs-Nafion ® lGCE) for dianabol (DB), a widely used steroid, was developed using a glassy carbon electrode (GCE) modified with functionalized carboxylated multi-walled carbon nanotubes (c-MWCNT) and Nafion ® . At pH 7 - 8, differential pulse-cathodic stripping voltammetry (DP-CSV) displayed two cathodic peaks at -0.85 and -1.35 V that varied linearly over a wide range (9.0 × 10 -9 (2.7 μg L -1 ) - 9.0 × 10 -6 (2.7 × 10 3 μg L -1 ) mol L -1 ) and 2.9 × 10 -6 (8.7 × 10 2 μg L -1 ) - 8.0 × 10 -5 (2.4 × 10 4 μg L -1 ) mol L -1 ) of DB concentrations, respectively. The low limits of detection and quantification at peak I (-0.85 V) were 2.7 × 10 -9 (8.1 × 10 -1 ng mL -1 ) and 9.0 × 10 -9 (2.7 ng mL -1 ) mol L -1 , respectively. The repeatability and reproducibility displayed relative standard deviations lower than 5%. The method was applied for DB analysis in human urine and subsequently compared with the standard HPLC method. Interference of common metabolites in biological fluids samples to DB sensing was insignificant. This method has distinctive advantages e.g. precise, short analytical time, sensitive, economical, reproducible and miniaturized sample preparation for DB analysis in biological samples of human origin.

A simple extractive spectrofluorimetric strategy for trace determination of mercury(II) ions in water employing procaine hydrochloride (PQ + ) as an ion pairing fluorescent tagging reagent has been established. The method was based upon the extraction of PQ + from aqueous iodide media onto dichloromethane as a ternary complex ion associate [(PQ + ) 2 .(HgI 4 ) 2- ] at pH 9.0-10.0 with subsequent quenching at λ ex/em  = 268/333 nm. The developed strategy exhibited a linear range 20-140 nM with a lower limit of detection (LOD) 6.1 nM, respectively. Intra and inter-day laboratory accuracy and precision for trace analysis of mercury(II) ions in water were performed. Complexed mercury(II) species in real water samples were evaluated along with chemical speciation and successful comparison with most of the reported methods. The method was validated by standard inductively coupled plasma-optical emission spectrometry (ICP-OES) method in terms of student's t- and F tests at 95% confidence interval. The method offers rapidity, selectivity, cost-effectiveness, robustness, and ruggedness. Graphical Abstract Schematic illustration of the proposed sensing mechanism for mercury(II).

The in situ preparation of ethylene dimethacrylate porous polymer monoliths within 20 μL polypropylene pipette tips, bound via surface grafted methacrylate anchor sites, is reported. Gold nano-particles (AuNPs) were immobilised onto the monolith pore surface utilising azlactone chemistry and coverage verified using field emission scanning electron microscopy. Erythrina cristagalli lectin (ECL) was immobilised upon the attached AuNPs via a bio-functional linker. The ECL-modified tip was successfully applied for the enrichment of galactosylated protein (desialylated transferrin) versus a non-galactosylated protein (ribonuclease B) due to the specificity of ECL. Reversed-phase capillary HPLC was used to validate the efficiency and selectivity of the developed micro-extraction phase which resulted in an increase in extraction recovery of ∼95% due to the AuNP enhanced surface area. Further specificity of the ECL-modified tip was demonstrated with a complex mixture of non-glycosylated and glycosylated proteins with differing terminal sugar structures. Finally, the lectin affinity phase was applied to a galactosylated glycoproteins spiked Escherichia coli cell lysate to successfully demonstrate matrix tolerance.

A solid phase extraction, liquid chromatography and fluorescence (SPE-RPLC-FL) based protocol for the determination of free monosaccharides in highly complex raw material powders and formulated fermentation feedstocks and broths has been developed. Monosaccharides within sample extracts were derivatised pre-column with anthranilic acid and the derivatives separated using reversed-phase LC with fluorescence detection. Using a 2.1 mm × 50 mm 1.8 µm Zorbax Eclipse XDB-C18 column, a flow rate of 0.4 mL min-1 and an acetonitrile gradient in a sodium acetate buffer (pH 4.3; 50 mmol L-1) the baseline resolution of glucosamine, mannosamine, galactosamine, galactose, mannose, glucose, ribose, xylose, fucose and sialic acid within 20 minutes was achieved. Pre-column derivatisation involved combining a 30 mg mL-1 solution of anthranilic acid in a 1 : 1 ratio with an aqueous standard prior to injection. Standard analytical performance criteria were used for evaluation purposes, with the method found to exhibit LOD's as low as 10 fmol, and be linear and precise (%RSD < 2.2% (n = 7). The method was applied to the analysis of a range of highly complex biopharmaceutical production samples, including yeastolate powders, chemically defined media and in-process fermentation broth samples. Sample preparation involved passing an aqueous sample through a C18 solid phase extraction cartridge to trap hydrophobic peptides and vitamins, with recovery of all test sugars exceeding 90%. Finally, standard statistical analysis was performed on samples taken from different lots in order to estimate lot-to-lot variability.

Two rapid, sensitive and quantitative methods for the determination of the cysteine and cystine ratio in complex defined media feedstock using monolithic reversed-phase liquid chromatography (RPLC) and RPLC-MS are presented. Cysteine is pre-derivatised with purified 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT) and separated from other derivatisation products on a narrow-bore 50mmx2mm I.D. monolithic C(18) column with UV detection at 355nm. For reversed-phase LC (RPLC) the separation is carried out isocratically using a mobile phase of 50mM trichloroacetic acid (TCA) adjusted to pH 2.5 with lithium hydroxide (LiOH) and acetonitrile (83:14) pumped at 1.5mL/min with an elevated column temperature. For RPLC-MS an ammonium acetate and acetonitrile gradient method was developed with a reduced flow rate of 0.3mL/min. The treatment of the samples consisted of dividing them into two aliquots, the first aliquot is analysed for cysteine and the second aliquot is analysed for cystine after its quantitative reduction to cysteine using tris(2-carboxyethyl)phosphine (TCEP). Both methods are linear, with R(2)>0.999 for 0.25-500microM for cysteine and 0.25-250microM for cystine using the LC-UV method, sensitive, with detection limit of 36nM for cysteine, and precise, with < or =1.1% RSD for both retention time and peak area (n=6). Samples (n=31) of an industry standard and supplied chemically defined media feedstock were analysed, finding cysteine ranging from 1.56 to 2.26microg/mL and cystine from 1062.02 to 1348.13microg/mL., (Copyright 2010 Elsevier B.V. All rights reserved.)