Journal of Analytical Chemistry最新文献

A solution anode glow discharge (SAGD) was established as a miniaturized excitation source of atomic emission spectrometry (AES) for the detection of Cd in rhizosphere soil, carrot, and carrot leaf samples. The working conditions, such as electrolyte pH, discharge voltage, support electrolyte, solution flow rate, and discharge distance, were systematically optimized. The effect of 31 foreign ions on the Cd determination was investigated. In addition, the influences of matrix modifiers on the Cd signal intensity and interference elimination were examined in detail. The results showed that under the optimal operating parameters, the presence of Fe³⁺, Co²⁺, Pb²⁺, Cu²⁺, Cr³⁺, and Tl³⁺ ions at 30 mg/L causes severe depression effects for the detection of Cd, and adding ascorbic acid as a matrix modifier can reduce the matrix interference, improve sensitivity, and lower the limit of detection (LOD). The LOD of Cd is 4.4 μg/L, and power is below 8 W using SAGD without any matrix modifier. Compared with the solution cathode glow discharge–atomic emission spectrometry (SCGD-AES), the sensitivity is improved about 11-fold, and the power is consumed only about one-sixth. The analysis results of SAGD-AES are in agreement with the Cd-certified reference material and verification values measured by inductively coupled plasma atomic emission spectroscopy, suggesting that proposed method has high accuracy and reliability.

A composite based on Fe₃O₄ nanoparticles, graphene oxide, and a ionic liquid (1-butyl-3-methylimidazolium-2-carboxylate) is proposed as a sorbent for the extraction of bisphenol A (BPA) from bottom sediments by matrix solid-phase dispersion (MSPD). The saturation magnetization of the synthesized sorbent is 34 emu/g. Grinding of bottom sediments and subsequent grinding with a sorbent was carried out in a ball mill. Some stages of MSPD were partially automated, in particular, the procedures of magnetic separation, BPA desorption, and sorbent regeneration. The recovery of BPA under the experimentally selected conditions (sorbent mass 0.5 g, time required to grind the sorbent 5 min) was 94%. The sorbent can withstand four sorption-desorption cycles without a loss of sorption capacity. To purify the matrix from interferents, washing with n-heptane was proposed. Bisphenol A was determined by gas chromatography–mass spectrometry after derivatization with acetic anhydride. The analytical characteristics of the method were established using model samples of bottom sediments artificially contaminated with BPA. The limit of determination using the developed method is 0.1 μg/kg, the linearity range of the calibration curve is 0.3–12 μg/kg (r² = 0.994). As real samples for analysis, we used bottom sediments selected near the discharge of wastewater treatment plants in the city of Voronezh (Voronezh River and Don River). The BPA concentration in bottom sediments is 3.83–6.52 μg/kg.

Hydrogen sulfide, a toxic gas, can be released into the air during oil and natural gas extraction, metallurgical production, and the storage and processing of industrial and household wastes. The determination of hydrogen sulfide in the atmosphere is a pertinent task in analytical chemistry. The established methods, such as chromatography or mass spectrometry, are unsuitable for continuous monitoring in hard-to-reach places. This creates a practical need for a low-cost chemical sensor that offers high sensitivity and selectivity. In this study, gas-sensitive materials based on In₂O₃ with catalytic additives—primarily palladium (as PdO) and silver (as Ag₂O)—were synthesized. The synthesis proceeded in several stages. Initially, an In(OH)₃ sol was prepared, followed by centrifugation and thermal treatment to yield indium oxide nanopowder. The material was characterized by transmission electron microscopy (TEM) and X-ray powder diffraction. Subsequently, the indium oxide nanopowder was blended with catalytic additives and a binder to form a paste. The gas-sensitive material was obtained by annealing the paste at 750°C. The sensor properties of these gas-sensitive materials were investigated with respect to hydrogen sulfide and carbon monoxide under nonstationary temperature conditions: heating to 450°C for 2 s and cooling to 100°C for 13 s. The study demonstrated that nanodispersed indium oxide-based materials exhibit high sensitivity to hydrogen sulfide and exceptional selectivity.

A method was developed to fabricate a glassy carbon electrode with electrodeposited palladium particles and a molecularly imprinted polymer derived from nicotinamide. This approach enables the determination of dopamine in the presence of structurally related compounds. The incorporation of a polymer featuring specific recognition sites tailored to the template molecule significantly enhanced the sensitivity and selectivity of dopamine detection. The immobilization of palladium particles on the electrode surface further improved the selectivity of voltammetric dopamine determination, even in the presence of adrenaline and noradrenaline, which exhibited a 200 mV difference in oxidation peak potentials. The analytical signal showed a linear bilogarithmic dependence on dopamine concentration within the range 5.0 × 10^–9 to 5.0 × 10^–3 M. This method was successfully applied to an analysis of urine samples, demonstrating its practical utility in real-world applications.

Poly- and perfluoroalkyl substances (PFASs) have attracted great scientific attention because of their environmental persistence, bioaccumulation potentials, and toxicity. This study validated a simple and efficient sample preparation method for determining extractable PFASs, including 12 perfluoroalkyl carboxylic acids and 4 perfluoroalkyl sulfonates. The samples underwent ultrasonic extraction, and the extracts were cleaned up by dispersive solid-phase extraction technique with graphitized carbon if necessary. PFAS quantification was performed by a liquid chromatography-tandem mass spectrometry system. The instrument provided analytical signals for all target compounds with good repeatability (RSD < 15%), reproducibility (RSD < 20%), linearity (R² > 0.99), and low detection limits (0.10–1.0 ng/mL). The validated method exhibited adequate recovery (70–115%), precision (RSD < 15%), and method detection limits (0.020–0.70 ng/g). This validated method was applied to analyze PFASs in several food packaging samples collected in Vietnam, showing very low levels (range 0.090–2.9 ng/g; median 0.72 ng/g) derived from unintentional sources.

The second and final part of the review. Provides general information about sub- and supercritical extraction (pressurized liquid extraction, subcritical water extraction, supercritical fluid extraction), matrix solid-phase dispersion and the QuEChERS method. Based on an analysis of review works, information on the features of sample preparation using these methods is systematized, experimental parameters affecting extraction efficiency are considered, and examples of using these methods for isolating organic compounds in the analysis of solid environmental samples, food products, and plants are given.

Singly charged background argide ions ArH⁺, ArN⁺, ArO⁺, and Ar²⁺ create strong spectral interferences in elemental and isotopic analysis by inductively coupled plasma mass spectrometry (ICP MS). In this study, we experimentally investigated the behavior of these ions depending on variations in high-frequency plasma power and argon carrier gas flow rate. Theoretical analysis was performed using thermodynamic modeling to predict the behavior of these argide ions on changes in plasma temperature and argon flow rate. Common patterns in the intensity of these major background ions and changes in their formation efficiency at different working parameters of the ICP are noted. A good agreement between the observed experimental dependences and those derived from thermodynamic models is noted.

This work was devoted to a study of the composition of protein concentrates from amaranth grain (Amaranthus hypochondriacus L.) of variety Voronezh. Amaranth protein concentrates were obtained by alkaline extraction of proteins and neutralization of the solution followed by ultrafiltration, by separating the starch fraction with amylolytic enzymes, and by alkaline extraction of proteins and their precipitation at pH 4.5. Conditions for the extraction of proteins followed by chromatography–mass spectrometric analysis and identification were selected. It was found that proteins from amaranth grain were more effectively extracted with a buffer with urea at protein concentrations of 1.7, 1.9, and 2.9 mg/cm³ in solution, respectively, while a buffer with detergents was more effective for the extraction of low-molecular-weight proteins at protein concentrations of 4.9, 2.9, and 9.0 mg/cm³ in solution, respectively. As a result of HPLC–MS/MS analysis followed by identification and search in the UNIPROT database, it was established that the main protein of amaranth grain is 11S-globulin, which acts as a reserve protein of amaranth seeds. In amaranth concentrates, 14 unique proteins belonging only to A. hipochondriacus L. were identified, and also proteins that did not belong to this species were reliably identified. Based on the results of semiquantitative analysis of the peptide profile of amaranth grain protein concentrates, a high frequency of occurrence of the main 11S-globulin proteins was established in all samples. The frequency of occurrence of other proteins in samples obtained by different methods differed significantly due to the peculiarities of protein isolation from amaranth grain. The results obtained can be used to prepare plant protein concentrates with a given protein composition.

In this brief review, we consider various characterizations of “monomeric” reversed phases for elucidating the interactions governing adsorbate retention in liquid chromatography. Conventional methods related to the assessment of retention capacity and hydrophobicity (specifically methylene selectivity) using single mobile phase compositions are discussed with a focus on dispersion interactions, along with their inherent strengths and limitations. An alternative approach involving separation maps through relative retention analysis is proposed. It is noted that, in real reversed-phase adsorbents, the density of the attached alkyl chains is typically one half of that of solid n-alkanes. In this case, adsorbate molecules to penetrate into the attached phase, and the process depends on the molecular shape. Consequently, conventional “monomeric” reversed phases exhibit specific selectivity towards substances with specific structures. The review also notes that current analytical methods often do not pay sufficient attention to the difference between the substance retention mechanisms, absorption and adsorption, because the predominant parameters of these mechanisms are quite different. Moreover, in the two most widely used very interesting and informative methods, linear solvation energy relationships (LSERs) and the hydrophobic-subtraction model, this characteristic has not received due attention. Taking into account that the method does not distinguish adsorbates retained by different mechanisms, absorptive versus adsorptive, to the obtained significant discrepancies between the calculated and experimental data do not seem extraordinary. The interpretation of the results of an LSER analysis is also complicated by uncertainties in the contributions of partial properties of adsorbates in both mobile and stationary phases to the total solvation energy, as only their difference is typically calculated. Nonetheless, a comparison of different columns in identical mobile phases can yield informative insights. A drawback of the second approach is the necessity of using multiple columns with substantial qualitative differences in the adsorbate retention among them. Furthermore, a possibility of the decomposition of all interactions into distinct types seems questionable, because the method does not involve any orthogonal (independent of the applied calculation method) properties.

The application of composite films consisting of crosslinked polyvinyl alcohol and magnetite as sensitive elements in the determination of the composition of aqueous solutions by digital colorimetry is described. A novel approach to fabricating composite materials of the composition hydrophilic polymer–magnetite is proposed; it involves the precipitation of Fe₃O₄ particles in ammonia vapors. The sensor films produced by this method were employed for determining the volume fraction of alcohol in products characterized by high alcohol content. The limit of detection for ethanol was determined at 63 vol %, while for isopropanol, it 24 vol %. The efficacy of the proposed sensor materials was assessed through in an analysis of liquid hand sanitizers.