Journal of Analytical Chemistry最新文献

Complex formation of vanadium(V) with 4-(2',3',4'-trihydroxyphenyl)-3-nitro-5-sulfoazobenzene (R) in the presence of cationic surfactants (CS), cetylpyridinium chloride (CPCl), cetylpyridinium bromide (CPBr), and cetyltrimethylammonium bromide (CTMABr), is studied. Vanadium(V) and R form a colored complex at a component ratio of 1 : 2 and pH of 5.0–5.5. The absorbance maximum of the complex is at 449 nm, while the reagent under these conditions absorbs light at 395 nm. In the presence of cationic surfactants, mixed-ligand complexes with a component ratio of V(V) : R : CS = 1 : 2 : 2 are formed, which results in a bathochromic shift of the absorbance maximum. Additionally, the pH value for the maximum complex formation shifts to a more acidic medium compared to the homoligand V(V)–R complex. The absorbance of the V(V) : R : CPCl, V(V): R : CPBr, and V(V) : R : CTMABr complexes is maximal at 457, 461, and 466 nm, respectively. The yield of these complexes is the highest at pH of 3.5–4.0 for VV(V) : R : CPCl and V(V): R : CPBr, and at a pH of 2.5–3.0 for V(V) : R : CTMABr. The formation of both homoligand and mixed-ligand vanadium(V) complexes depends on the reaction time, temperature, and concentrations of the reacting components. The determined stability constants indicate the high stability of the resulting mixed-ligand complexes. The specific conductivity of the complexes under the optimal conditions of complex formation was determined using conductometric titration. Calibration curves for the determination of vanadium(V) as homoligand and mixed-ligand complexes are linear. The effect of foreign ions and masking agents on the determination of V(V) as homoligand and mixed-ligand complexes was analyzed; it was shown that the presence of cationic surfactants significantly increases the selectivity of the reaction. An analysis of water samples from Lake Khanbulan, Lankaran District, Azerbaijan Republic using the developed procedure showed the presence of small amounts of vanadium(V).

The presented work focused on the preparation of a voltammetric sensor for hydroquinone (HQ) determination using a polycrystalline platinum electrode modified with Alizarin Red S (ARS). The electrode was prepared by electropolymerization of ARS on a platinum electrode through the application of 100 cyclic voltammetric segments between –0.4 and 1.2 V against Ag/AgCl (quasi-reference electrode). The modified poly (ARS)-Pt electrode was characterized in terms of stability and cyclic voltammetric behavior as a sensor for HQ in aqueous media. The modified electrode showed excellent stability and higher current than the unmodified electrode for the electrooxidation of HQ. Thus, the oxidation of HQ at poly (ARS)-Pt electrode exhibits notable electrocatalytic performance. The limit of detection is 0.16 µM, and the standard curve exhibits a linear relationship over the range from 0.25 to 15 µM (R² = 0.999). Investigation of the response to some potential interferences indicated that the electrode is unresponsive to Na⁺, K⁺, Mg²⁺, Ca²⁺, Zn²⁺, Mn²⁺, Mo²⁺, Co²⁺, Bi²⁺, Cd²⁺, Ni²⁺, Al³⁺, ({text{NO}}_{3}^{ - }), ({text{SO}}_{4}^{{2 - }}), Cl^–, phenol and resorcinol, but shows marginal change towards Hg²⁺ and Cu²⁺. Recovery tests indicated recovery values between 97.0% and 100.81% when analyzing real samples at the modified electrode.

A magnetic solid-phase extraction method with the dispersion of magnetic hypercrosslinked polystyrene (MHCPS) by carbon dioxide is proposed for the extraction and preconcentration of amphenicols (chloramphenicol, florfenicol, and thiamphenicol) from honey and milk before their determination by HPLC–MS/MS. Effervescent tablets, consisting of sodium bicarbonate, citric acid, and MHCPS in the case of honey and sodium bicarbonate and MHCPS in the case of milk, were used. The conditions for obtaining tablets were selected (the amount and ratio of the acid, base, and MHCPS in the composition of a tablet and its mass), ensuring the quantitative release of amphenicols. Procedures for the determination of amphenicols in honey and milk with the dispersion of the sorbent by carbon dioxide and the subsequent determination of the compounds by HPLC–MS/MS are developed. The limits of detection are 0.3–1 and 0.02–0.05 μg/kg for honey and milk, respectively.

The results of an experiment assessing the applicability of solutions of 6-oxo-2-phenylimidazo[1,2-b]pyrido[4,3-e][1,2,4]triazine-7(6H)-yl)acetic acid on plates and cellulose substrates for detecting excessive levels of volatile organic compounds associated with endometritis inflammation relative to biologically normal levels are considered. The fluorescent properties of the dye are studied using gynecological mucus from cows collected in various periods (pre- and post-partum) and nasal mucus from newborn calves. The test system responses were compared with clinically established diagnoses and the results of a microbiological study. An evaluation of the test systems revealed a false positive rate of no more than 11% and a false negative rate of 2%. Other characteristics, such as specificity, accuracy, and precision of the test systems based on 6-oxo-2-phenylimidazo[1,2-b]pyrido[4,3-e][1,2,4]triazine-7(6H)-yl)acetic acid were also assessed. The potential application of this fluorophore to the rapid on-site diagnosis of endometritis inflammation in cows is considered promising based on these findings.

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.