Journal of Analytical Chemistry最新文献

Procedures for the identification and determination of a number of antioxidant, anticorrosive, and dispersant additives (ionol, diphenylamine, zinc dialkyldithiophosphate, and diester oil) in mineral hydraulic oils were proposed. They included preliminary solid-phase extraction of analytes on a cartridge with hydroxylated silica gel with the subsequent detection by reversed-phase high-performance liquid chromatography. The recovery of analytes was higher than 97%, and the limits of determination and detection of functional additives in mineral hydraulic oil were 0.001 and 0.0006 wt % for ionol, 0.01 and 0.008 wt % for zinc dialkyldithiophosphate, and 0.0005 and 0.00025 wt % for diphenylamine, respectively. It was established that Shell Tellus S2 V 46 mineral hydraulic oil contained 0.16% zinc dialkyldithiophosphate and 0.2% diphenylamine, and Total Hydragri ISO VG 46 contained 0.14% ionol and 0.17% zinc dialkyldithiophosphate. The molecular-weight characteristics of polymer additives to hydraulic oil were determined by gel permeation chromatography, and the concentration of a viscosity additive in a real sample was calculated. The procedures are appropriate for the determination of functional additives and the quality control of mineral hydraulic oil.

A new complexing analytical reagent is synthesized by the condensation of salicylic aldehyde with isatin hydrazone. The dissociation constant of the reagent pK = 9.48 ± 0.03 is determined. The structure of the reagent is studied by X-ray diffraction and NMR spectroscopy. The complexation of palladium(II) with [(2-hydroxybenzaldehyde)-3-isatin]-bishydrazone (R) in the presence and absence of diantipyrylmethane (DAM), 8-hydroxyquinoline (8-HQ), and diphenylguanidine (DPG) is studied by spectrophotometry. Optimum conditions for complexation (λ_opt, pH_opt) are selected. It is found that palladium(II) forms colored mixed-ligand complexes with the reagent in the presence of the third component, DAM, 8-HQ, or DPG. The Pd(II)–R complex exhibits the maximum absorbance at the wavelength 440 nm, and the Pd(II)–R–DAM, Pd(II)–R–8-HQ, and Pd(II)–R–DPG complexes, at 465, 490, and 450 nm, respectively. The molar absorption coefficients for Pd(II)–R are 6000 L/(mol cm), and for Pd(II)–R–DAM, Pd(II)–R–8-HQ, and Pd(II)–R–DPG they are 10 000, 8000, and 7500 L/(mol cm), respectively. The optimum pH value for Pd(II)–R is 4, for Pd(II)–R–DAM and Pd(II)–R–DPG it is 2, and for Pd(II)–R–8-HQ it is 3. The stability constants of the complexes are determined. The region of adherence to the Beer law is found. The equations of the calibration graphs are constructed using the least-squares technique. The ratio of components in the composition of homogeneous and mixed-ligand complexes is determined by the methods of isomolar series, continuous variations (Job’s method), and slope. All methods show that the ratio of the Pd(II)–R components in the binary complex is 1 : 2, and in the mixed-ligand complexes Pd(II)–R–8-HQ and Pd(II)–R–DPG – 1 : 1 : 1, Pd(II)–R–DAM – 1 : 2 : 1. The effect of some foreign ions and masking substances on the formation of homogeneous and mixed-ligand complexes of palladium(II) is studied. It is found that Na(I), K(I), Ca(II), Ba(II), Cd(II), Ni(II), Cr (III), Co(II), Pd(IV), platinum-group metals, and many anions do not interfere with the determination of Pd(II). The developed procedure is applied to the determination of trace amounts of palladium(II) in a nickel anode material.

Remdesivir, the first United States Food and Drug Administration-approved drug for emergency use for the treatment of SARS-Covid-19, is also considered a first-in-class medication. It is sold under the brand name Veklury. Remdesivir is a prodrug, and it allows intercellular transformation into GS-441524 monophosphate and subsequent biotransformation into GS-441524 triphosphate, a ribonucleotide analog inhibitor of viral RNA polymerase. The European Union also approved the use of Remdesivir for the treatment of Covid-19. Subsequently, the Food and Drug Administration approved the emergency use authorization of Remdesivir for Covid-19 in combination with Baricitinib. The current review presents various analytical methodologies for the determination of Remdesivir in bulk, in pharmaceutical formulations, and in biological samples, including ultraviolet-visible spectroscopy, fluorescence spectroscopy, liquid chromatography, and other hyphenated methods. This comprehensive summary should provide important information to the analyst interested in the development of analytical methods.

An analytical approach is proposed to diagnosing organic matter present on the surface of human skin by combining sampling with analysis by oxythermography. The sampling device is a quartz rod with a roughened terminal surface, which is pressed to the targeted skin area. The method quantifies the amount of oxygen consumed for the oxidation of organic material transferred from the skin to the sampler surface. It does not require chemical reagents, as the oxidation process occurs in an air stream. The measurable concentration range of organic substances, expressed in terms of oxygen consumption, spans from 41 to 250 µg O₂/cm². The relative standard deviation ranges from 1 to 5%. The method enables the assessment of the skin condition based on the “skin oiliness” parameter and may be applied to routine monitoring in medical cosmetology, for instance, during acne treatment.

Interest in the presence of microplastics in processed food continues to grow, yet studies focusing on the methodological aspects, as well as quality assurance (QA) and quality control (QC) procedures, remain limited. Thus, this study focuses on the assessment of methodological aspects employed in microplastics in processed food studies using the Criteria for Reporting and Evaluating Ecotoxicity Data framework. A total of 65 processed food studies conducted between 2015 and 2025 were selected for this assessment. This assessment involved 14 criteria, categorized into three phases: pre-laboratory work, laboratory work, and post-laboratory work. One study achieved the highest score of 27 out of 28, with the average total score ranging from 20 to 24. The lowest overall score was 8. In the pre-laboratory work, the most frequently reported aspect was sample size. During the laboratory work, laboratory preparation received the lowest score of 2, and 49 studies scored 0 for positive controls. In the post-laboratory work, most studies provided particle characteristics; however, for polymer color, 16 studies received a score of 0. The steps taken in pre-laboratory and laboratory work directly impact the accuracy and validity of the data in the post-laboratory work. These scores further reflect the need for stricter QA and QC standards related to the methodological aspects. Future studies can use the current assessment of methodological aspects as a reference to obtain reliable and valid microplastic data, which will increase confidence in their use in toxicity assessments.

Vitamin A (VA) is composed of various unsaturated organic compounds, such as retinol, retinal, and retinoic acid, along with several provitamin A carotenoids, with β-carotene being the most significant. This nutrient is essential for a broad spectrum of physiological functions in the human body. Various methodologies have been established to measure VA concentrations in diverse samples. Flow injection analysis (FIA) provides multiple advantages, including versatility, precision, cost efficiency, rapidity, and easy automation. This article aims to emphasize the significance and sources of VA, while also describing different chemiluminescence (CL) systems in use based on both direct and indirect CL in conjunction with the FIA system. Furthermore, it discusses FIA assays for the quantification of VA utilizing CL and spectrophotometric detection. A summarized table outlining the analytical characteristics of various techniques employed for VA analysis is also presented.

Platinum nanoclusters (PtNCs) with fluorescent properties have been prepared using Acid Red G as a stabilizer, potassium hexachloroplatinate as a precursor, and sodium borohydride as a reducing agent, with a reaction time of about 2 h. The optimal excitation wavelength of the synthesized PtNCs is 333 nm, and the optimal emission wavelength is 431 nm. It has been found that tetracycline (TC) can significantly quench the fluorescence of the synthesized PtNCs. A good linear relationship was observed between the quenching value (F₀–F) of the PtNCs fluorescence intensity and the TC concentration in the range of 5.00–50.00 μM, with a correlation coefficient (r) of 0.9962. Thus, a fluorescence analysis method for measuring TC was established based on the above phenomenon, with a detection limit of 2.04 μM (3σ/k). The standard concentration of TC was added to tap water for spiked recovery experiments, the recovery rate was in the range of 97.37–100.03%, and the relative standard deviation ranged from 1.96 to 4.76%. This indicates that the established method has demonstrated feasibility for detecting TC content in water samples. Meanwhile, PtNCs were used as fluorescent probes to achieve visual quantitative detection of TC concentration using smartphones and colorimetric analysis software.

This study introduces a dual-technique strategy for levofloxacin quantification, combining ultraviolet-visible spectrophotometry and a microfluidic paper-based analytical device (µPAD) to address the need for cost-effective, precise pharmaceutical quality control. Leveraging the reaction between levofloxacin and chlorophenol red, both methods form a colored complex (λ_max = 574 nm) via an acid-base interaction stabilized by electrostatic and hydrogen bonding. The spectrophotometric method demonstrates high sensitivity (limit of detection (LOD): 2.50 µg/mL, linear range: 5–100 µg/mL) with robust intra-day (relative standard deviation (RSD): 0.946–1.730%) and inter-day precision (RSD: 1.401–2.198%), alongside recovery rates of 91.5–102.6%. In contrast, the µPAD offers portability and rapid analysis (LOD: 10.119 µg/mL, linear range: 100–1000 µg/mL), achieving comparable accuracy (recovery: 90.6–96.1%) with minimal reagent consumption. Both techniques were validated according to the International Council for Harmonization guidelines, exhibiting negligible matrix interference in commercial formulations (Levolen, Levobact, Levofloxacin Vitapure). The spectrophotometric method excels in laboratory settings for precision, while the µPAD enables on-site testing, aligning with green chemistry principles. This dual approach bridges technological gaps, providing versatile tools to ensure accurate dosing, support antimicrobial stewardship, and enhance global pharmaceutical quality control.

The urine protein-to-creatinine (P/C) ratio is a rapid and accurate method for measuring proteinuria in the diagnosis of kidney diseases. A smartphone device enables rapid determination of creatinine and proteins in urine. A smartphone-based method was developed and validated for the detection of the P/C ratio in this study. Clinical urine samples were also analyzed and compared to the Beckman Coulter AU5800 results for correlation assessment. For proteinuria, the limit of blank (LOB) and limit of detection (LOD) were 4.23 and 8.8 mg/dL, respectively, with a lower limit of quantification (LOQ) of 9.2 mg/dL and a linear range from 9.2 to 122 mg/dL. The intra-batch precision coefficient of variation (CV) was 2.5%, and the inter-batch precision CV ranged from 3.0 to 3.3%. For creatinine, the LOB and LOD were 13.2 and 17.9 μmol/L, respectively, with a LOQ of 28 μmol/L and a linear range from 28 to 209.12 μmol/L. The intra-batch precision CV was between 2.7 and 2.8%, and the inter-batch precision CV was between 2.9 and 3.8%. The smartphone-based method for P/C detection is a reliable, cost-effective, and portable option for accurately measuring urinary protein and creatinine, suitable for remote diagnostics and home health checks.

Microplastic emissions to the environment increase every year. Over the past twenty years after the first publication on the study of microplastics, the problem of the global environmental pollution by synthetic materials has been confirmed, its toxicological effect has been proven at all levels of the organization of biosystems, including human health. Spectral, chromatographic, microscopic, and thermal methods of analysis are used to study microplastics. This review considers these groups of methods in the context of their application to the identification of microplastics and the determination of toxic substances associated with them.