Journal of Analytical Chemistry最新文献

Nickel-titanium-palladium shape memory alloys show broad application prospects due to their shape memory effect and superelasticity in high-temperature environments. Nickel serves as the pivotal constituent in the material system, with its concentration and spatial distribution critically governing the phase transition temperature, mechanical performance, and high-temperature stability, thereby dictating the alloy’s functional behavior. A gravimetric method was developed for nickel determination in Ti–Ni–Pd shape memory alloys. Key analytical parameters, including dissolution conditions, interference effects from matrix elements, dimethylglyoxime concentration (optimized at 30 mL of 10 g/L solution), and precipitation incubation (90 min at a controlled 70°C), were systematically investigated. Method validation demonstrated excellent precision (RSD < 0.5%, n = 7) and accuracy (99.4–100.4% recovery rates) through spike recovery experiments. A key advancement lies in elucidating the competitive coordination mechanism between palladium and nickel complexes with dimethylglyoxime, which enabled the development of a masking protocol to mitigate Pd interference. These optimizations significantly improved methodological robustness, achieving above 99% recovery rates for nickel in complex matrices while maintaining operability under routine laboratory conditions.

This study presents an efficient and eco-friendly approach for the removal of the antibiotic moxifloxacin (MX) from wastewater via hollow carbon spheres (HCSs) as adsorbents, demonstrating for the first time the use of defect-rich and highly porous HCSs for MX adsorption under optimized conditions via central composite design (CCD). HCSs, selected for their high surface area and hollow structure, were employed as adsorbents in the MX removal process. The optimization of key variables, including the initial MX concentration, pH, ionic strength, and contact time, was achieved through CCD. High-performance liquid chromatography with a C18 column was used to quantify the MX concentrations before and after adsorption. The quadratic regression model was analyzed via analysis of variance (P < 0.01) to ensure statistical robustness. The CCD model identified the optimal conditions for MX adsorption, yielding a significant quadratic model (P < 0.01) and a high adsorption capacity of 823 µg/mg. The optimal conditions were a pH of 10.0, ionic strength of 0.3 M, MX concentration of 15 µg/mL, and contact time of 1 h. Adsorption followed the Langmuir isotherm model, indicating a monolayer adsorption mechanism. The mean recovery of MX on the HCSs was 97.9 ± 2.7%, confirming the model’s accuracy and reliability. These findings highlight HCSs as effective and sustainable solutions for mitigating pharmaceutical pollution in water. The alignment with the Langmuir isotherm model supports the predictability and control of the adsorption process. By minimizing chemical use and reducing environmental impact, this method aligns with green chemistry principles and promotes cleaner water, sustainable industrial practices, and ecosystem protection. In addition, future studies with pilot-scale testing and engineering collaboration will help adapt and scale this approach for real wastewater treatment applications, supporting its practical and industrial implementation. HCSs thus demonstrate significant potential for scalable environmental remediation, offering a step forward in the fight against antibiotic contamination and resistance.

The features of planar (thin-layer) chromatography of several linear non-ionic polysaccharides (amylose, pullulan), their visualization by post-chromatographic derivatization with iodine, and the factors influencing this process are described. It is shown that the coloration of pullulan results from the formation of pseudoclathrate complexes of molecular iodine–iodide–pullulan in short helical segments of the polysaccharide, as well as iodine absorption in the bends of the polymer chain. It was established that the shift of the spectral absorption maximum of amylose (λ_max ~ 600 nm, blue coloration) to the shorter wavelength region (λ_max = 560 nm, red-brown coloration) is associated with specific interactions of starch with silica and the formation of a molecular iodine–iodide–anion–amylose–silica gel complex. It was demonstrated that the intensity of iodine staining of high-molecular-weight polysaccharides does not depend on their degree of polymerization, and polysaccharide visualization by the iodine reaction in thin-layer chromatography is possible only on neutral forms of silica sorbent.

A new electrochemical approach to enzyme-linked immunosorbent assay (ELISA) on magnetic microparticles functionalized with antibodies specific to the cardiac biomarker NT-proBNP is described. Alkaline phosphatase was selected as the enzyme label; the signal was detected by differential pulse voltammetry on disposable electrodes. The method offers high sensitivity, with a limit of detection of ~35 pg/mL, and a short analysis time of down to 20 min, which makes it promising for clinical applications. The key parameters, including component concentrations, temperature, and incubation time, were optimized. The procedure was validated on 34 serum samples from healthy individuals and patients with cardiovascular diseases. To assess clinical applicability, a correlation analysis was performed between the electrochemical signal intensities and the concentrations obtained on the Mindray BS-800 and Getein-1100 analyzers. Statistical analysis showed strong linear correlations between the signal obtained by the developed procedure and the target protein concentrations in the samples: r = 0.96 with the Mindray BS-800 and r = 0.93 with the Getein-1100.

A series of silica-based sorbents with zwitterions in the functional layer attached via a spacer based on 1,4-butanediol diglycidyl ether is synthesized. The effect of structural fragments of the stationary phase on the chromatographic properties in the hydrophilic chromatography mode is studied, and multifunctional capabilities for separating neutral polar, hydrophobic, and negatively charged compounds are demonstrated. Based on the revealed regularities, a sorbent with high separation capacity for carboxylic acids is created, which allows the separation of 13 organic acids in 25 min with a resolution of at least 1.0.

The work reports the multielemental characterization of topsoil samples from the area of the spent 'French mines' situated at Mt. Medvednica, near Zagreb, Republic of Croatia. Determination of the selected analytes was carried out by means of inductively coupled plasma optical emission spectrometry in three series of extracts that were prepared with deionized water, Mehlich-3 solution, and aqua regia. Results show that, with careful work, about 20 various chemical elements can be quantified in soil extracts prepared with deionized water. Also, it is shown that Mehlich-3 solution can be applied for the determination of many trace elements and not only for a set of 10 nutrients that were originally intended. A comparison of the efficiencies of the extraction methods was done by calculation of the ratios of the mass fraction values obtained by the three extraction reagents. Since weaker reagents allow the extraction of portions of elements that are relatively weakly bound to soil particles, the comparison of the mass fraction ratio values allows an assessment of the mobility of a metal(loid). Topsoil in the area of the spent mine is overloaded with metal(loid)s, as follows (the highest measured mass fractions values extracted with deionized water/Mehlich-3/aqua regia are given in brackets): As (0.521/1.44/337), Cd (0.011/0.911/4.24), Co (0.476/6.45/133), Cu (1.691/78.2/1227), Ni (0.851/6.81/152), Pb (4.40/893/11540), and Zn (1.25/38.4/817 mg/kg).

A new analytical method is proposed for the de termination and reporting of ‘acid-reactive silica’ under a fixed set of conditions that can be validated by a single laboratory. Acid-reactive silica exists as fluorosilicic acid during phosphate extraction processes. It is formed when fluoride inherent in the source rock (e.g., fluorapatite, francolite, fluorite) is liberated and reacts with siliceous minerals. To prevent corrosion, contamination with glassware, and volatile analyte losses—which have historically been major obstacles—the method involves acid digestion of the sample in Teflon-sealed cartridges during a microwave heating process, followed by elemental silicon analysis by inductively coupled plasma-optical emission spectroscopy. This method is useful for those in the mineral processing industry, particularly in processing phosphate minerals, where mineral acid is used to extract phosphate and other elements from geological ores. Predictive forecasting and quality control are needed in these industrial processes to control and recover fluorine byproducts, which pose enormous health and environmental concerns. Fluorosilicic acid itself is highly corrosive, but it is precipitated out in subsequent evaporation stages of phosphate production as sodium or potassium salts, thereby effectively making it a corrosion absorber for the holistic process. Due to this unique property, acid-reactive silica represents an invaluable but historically unestablished material property that requires definition.

A rapid, sensitive, inexpensive, and reliable analytical approach, directly suspended droplet microextraction (DSDME), was developed for the determination of aroma components in orange juice, coupled with gas chromatography-mass spectrometry. Hexane was used as the extraction solvent and placed on the top of the aqueous sample; several factors influencing the extraction and collection efficiency were optimized. The approach was used to determine some important aromas in orange juice, yielding relative recoveries of 91.66 to 109.94%, relative standard deviations of 2.04–6.91% (n = 5), and limits of detection of 0.2–1.9 μg/L. Satisfactory recoveries were obtained for all spiked compounds. The DSDME method requires minimal solvent, achieving high sensitivity with low detection limits for aroma compounds. The coupled miniaturized method was applied to the sensitive determination of aroma components in orange juice.

The special features of gas chromatographic identification of low-boiling organic solvents based on their retention index values on standard nonpolar polydimethylsiloxane stationary phases was considered with the use of 80 most common organic solvents as an example. It was shown that one-dimensional analytical parameters, such as retention indices, cannot provide unambiguous identification of all compounds of this group because their informative value R(RI) in this group is only about 29, which is lower than the number of objects in the group. To solve the problem, it is necessary to supplement the chromatographic data with independent characteristics, and refractive indices ((n_{D}^{{20}})) can be recommended as these characteristics because their determination requires minimal time and sample quantities. Nevertheless, about 10% of the solvents under consideration cannot be distinguished even based on the combinations of RI + (n_{D}^{{20}}). For comparison, the capabilities of using the dynamic viscosity of liquids as an additional analytical parameter were considered. The given table of retention indices for the most common organic solvents is of independent value for analytical practice.

Miniaturized methods for the adsorption separation and preconcentration of organic compounds include micro-solid-phase extraction (μ-SPE) and solid-phase microextraction (SPME). These methods are characterized by the reduced amounts of sorbents, test samples, and organic solvents; high preconcentration factors; and a combination of preconcentration and sample injection in a single device. Since the advent of μ-SPE (1989) and SPME (1990), numerous versions of these methods have been developed, which differ in the method of sample preparation, nature of sorbents used, and combination with methods of the subsequent determination of the preconcentrated substances. The popularity of these methods is illustrated by the large number of reviews summarized in this publication.