Journal of Analytical Chemistry最新文献

The effect of the concentration of mercaptopropyl groups chemically attached to a silica surface in the range from 0.18 to 0.76 mmol/g on the formation and color intensity of Pd(II) complexes with the attached groups, as well as mixed-ligand complexes of palladium(II) and silver(I) with attached mercaptopropyl groups and dithizone is studied. It is shown that, with an increase in the concentration of the attached mercaptopropyl groups, the color intensity of sorbents containing an equal amount of the adsorbed palladium(II) increases. In the case of the formation of mixed-ligand complexes of palladium(II) and silver(I) with the attached groups and dithizone, with an increase in the surface concentration of the attached groups, the intensity of the sorbent color decreases. Procedures for the sorption–photometric determination of palladium(II) as complexes with the attached groups and palladium(II) and silver(I) as surface mixed-ligand complexes are developed. It is concluded that, to achieve low limits of detection of elements as their complexes with the attached groups by the sorption–photometric method, the concentration of the attached groups should be maximum, and to achieve low limits of detection of elements as their mixed-ligand complexes with the attached groups and dithizone, the concentration of the attached groups should be minimum.

A methodological gap in the study of environmental nanoparticles is largely due to their extremely low concentrations—typically around 0.01–0.1%—in ash, dust, or soil, which significantly complicates their extraction and quantification. This study demonstrates the efficiency of a novel sample preparation protocol for volcanic ash samples, involving sequential dispersion in 0.1 M NaCl and 2 mM Na₄P₂O₇, followed by nanoparticle extraction by flow field-flow fractionation in a rotating coiled column, using a 2 mM Na₄P₂O₇ solution as an eluent. Thise method ensures an increase in the mass of the extracted nanoparticles by one order of magnitude and enables the detection of elements such as Be, Cr, Co, Zn, Ag, Sb, Te, Ta, W, Tl, and Bi in ash-derived nanoparticles from various volcanoes in concentrations below the limits of detection by ICP–MS using deionized water as an eluent. In addition, the results of the procedure are not distorted by analytical artifacts, such as the formation of poorly soluble calcium phosphates during sample preparation. This approach provides a foundation for the systematic studies of ash-derived nanoparticles from a wide range of volcanic types, as well as of urban dust.

Sorption methods, including solid-phase extraction, are widely used in the determination of platinum-group metals (PGMs), which is confirmed by a permanently large number of publications. This review is devoted to the description of different types of sorbents developed for the preconcentration and selective recovery of PGMs and their use in the analysis of geological, natural, and technological samples. Trends in the design of materials and physical fields to intensify the processes of the solid-phase extraction of PGMs are discussed. The review considers publications mainly for 2010–2025.

The solid-phase extraction of ion pairs formed between acidic azo dyes—Sulfonazo and Congo Red—and papaverine (1-(3,4-dimethoxybenzyl)-6,7-dimethoxyisoquinoline) on polyurethane foams is studied as a function of pH, phase contact time, and component ratio. A procedure is developed for determining papaverine in pharmaceutical formulations based on its adsorption as ion pairs with azo dyes, followed by detection on the adsorbent surface using diffuse reflectance spectroscopy and colorimetry.

Due to its pharmacological and biological activity, bee venom is used in the production of various drugs and pharmaceutical forms, including ointments and creams. Melittin is the main component of bee venom, and its presence in a drug preparation is characteristic of the presence of bee venom as a constituent. An approach to the detection of this characteristic peptide component of bee venom in semisolid dosage forms, which involves recovery and preconcentration using solid-phase extraction followed by liquid chromatography with mass spectrometric detection, was proposed. The specificity of the detection procedure was validated, and the limit of detection was 0.1 μg/g.

Sensors are developed for the amperometric determination of the antibiotics Cefur and Ceftr in aqueous solutions. The sensor electrodes were coated with a molecularly imprinted polymer (MIP). To assess the selectivity and molecular recognition ability of the sensors, the imprinting factor and selectivity coefficient were determined. The imprinting factor reached 5.3 for MIP-Cefur and 5.1 for MIP-Ceftr. The results demonstrated that the MIPs exhibited higher selectivity and recognition capability for Cefur and Ceftr compared to non-imprinted polymers. The antibiotics were quantified in aqueous solutions using the calibration curve method. The experimentally found concentration ranges for Cefur and Ceftr were from 1.0 × 10^–5 to 0.1 g/L. The limits of detection were 3.5 × 10^–6 g/L for Cefur and 6.6 × 10^–6 g/L for Ceftr. MIP-modified sensors were tested in the determination of antibiotics in wastewaters. The findings confirmed the applicability of amperometric sensors based on molecularly imprinted polymers to the determination of Cefuroxime sodium and Ceftriaxone sodium in both model and real aqueous solutions.

A method is proposed for the extraction and preconcentration of six of the most common endocrine disruptors (dimethyl, diethyl, dibutyl phthalates; bisphenol A; and octyl- and nonylphenols) from river bottom sediments. The analytes are extracted by two-stage preconcentration. At the first stage, the analytes are extracted from an aqueous solution with an ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate in the presence of a surfactant (sodium dodecyl sulfate). The volumes of the extractant and surfactant solution (12 vol %) are 200 μL and 0.5 mL, respectively. Extraction duration is 2 min. At the second stage, magnetic dispersive solid-phase extraction with magnetic coals of plant origin modified with reversed phases of n-octyltrimethoxysilane and n-octadecyltrimethoxysilane is used. The recovery of analytes by liquid–liquid extraction is 91–99% and by magnetic solid-phase dispersive extraction, 89–99%. It is found that, during solid-phase dispersive extraction, the best conditions for the extraction of disruptors are achieved at pH 5.2–7.0, sorption duration of 5 min using a centrifuge (4000 rpm), and sorbent portion of 25 mg. The use of two-stage preconcentration in combination with gas chromatography–mass spectrometry ensures the determination of endocrine disruptors in bottom sediments at a level of 0.4–0.7 μg/kg.

This work presents a microfluidic paper-based analytical device (µPAD) designed for the screening and measurement of ammonia and pH, utilizing mulberry fruit extract as a natural indicator. For ammonia determination, the method is based on a membraneless gas-separation microfluidic device. The µPAD co-nsists of three layers: the upper layer serves as the detection area, featuring two circles with a diameter of 8 mm, where mulberry fruit extract at pH 3.07 and pH 4.93 is applied for the measurement of ammonia and pH, respectively. Ammonia gas is generated in the lower donor layer and diffuses through the gap in the middle layer to the acceptor layer. The concentration of ammonia is determined by analyzing the color change of the mulberry fruit extract indicator. Images of the colored detection zones are captured using a smartphone camera, and their color intensity is analyzed with ImageJ software. For pH measurement, the color change is compared to a standard pH scale ranging from 1 to 14. The proposed method offers a linear calibration range from 0 to 150 mg/L N, with a limit of detection of 4.89 mg/L N. The relative standard deviation was 3.43% (at 50 mg/L N, n = 10). This method was successfully applied to measure ammonia and pH in natural water, pond water, wastewater, and fertilizer samples, with recovery rates ranging from 95 to 109%. The results obtained from the µPAD correlated well with those from the spectrophotometric method for ammonia and a pH meter for pH values.

An inductively coupled plasma atomic emission spectrometry (ICP–AES) method for the determination of iodine in CsGeI₃ perovskite materials has been developed. The method involves microwave digestion with a hydrochloric-nitric acid system (3 : 1) at 120°C for 10 min, followed by analysis using optimized ICP–AES parameters (radio frequency power: 1150 W, cooling gas flow: 12.5 L/min). The linear range of iodine determination was 1.00–60.00% with a determination coefficient (R² = 0.999). Recovery rates ranged from 98.6 to 102.1%, and the relative standard deviation (n = 11) was ≤3.4%. The method demonstrated high accuracy and precision, validated through analysis of CsGeI₃ samples from diverse sources.

Insecticides like dimethoate and oxydemeton-methyl are essential for crop protection, supporting food production. However, their overuse raises environmental and food safety concerns due to contamination and residues. A new spectrophotometric method was developed to monitor these insecticides in formulations and environmental samples such as water, grains, and vegetables. The proposed method is based on the redox reaction of the thiol (the hydrolytic product formed in an alkaline medium) in both insecticides, with ferric chloride, leading to the formation of Fe²⁺, which subsequently reacts with 1,10-phenanthroline to form colored complexes, measurable at 510 nm. The method obeys Beer’s law within the concentration ranges of 0.46–13.74 µg/mL for dimethoate and 0.49–14.76 µg/mL for oxydemeton-methyl. Reaction parameters such as hydrolysis time, solvent type, heating time, and reagent concentration were optimized to enhance the sensitivity and stability of the method. The recovery results from water and environmental samples demonstrated the good accuracy and precision of the method, with recoveries of 89–100.8% for dimethoate and 89.9–99% for oxydemeton-methyl, and a relative standard deviation of 0.29–1.96 and 0.23–1.91% for dimethoate and oxydemeton-methyl, respectively.