Journal of Analytical Chemistry最新文献

A modified method for the sample preparation of oils for the determination of carbazoles is proposed. This method involves oil deasphaltination and the sedimentation of the oil suspension in a 40-fold excess of n-hexane for one day. Unmodified silica is used instead of argentified silica. The carbazoles are eluted in one fraction. The conditions for the identification and quantitative determination of 9-methylcarbazole and 9-ethylcarbazole by the GC-TID are selected and the analytical characteristics of the determination method are found. The use of 3-nitro-9-methylcarbazole as an internal standard for determining carbazoles is justified, and its synthesis is performed. The presence and amount of carbazoles in oils from various fields, and a synthetic oil sample are detected and estimated. The results of determining carbazole in natural oils using the external and internal standard methods and the standard addition method are compared. It is shown that, within the error limits, all methods give identical results. The amount of carbazole in the natural oils of the studied samples was found to be in the range 0.14–2.61 mg/kg of oil. 9-Ethylcarbazole was found in four oil samples.

This review considers analytical methods using portable devices combined with smartphones. It covers studies from 2015 to 2024, with an emphasis on recent research. References are given primarily to reviews published in the past 5 years. Devices used in combination with smartphones are discussed, ranging from smartphone holders to portable visible, Raman, and infrared spectrometers, microscopes, and cytometers, as well as amperometric and potentiometric devices and portable microfluidic analyzers. Applications of smartphones to portable devices for immunoassay, polymerase chain reaction, and other nucleotide sequence determinations, to microfluidic devices, and to separation methods are reviewed. Paper-based test systems, photonic crystals, nanozymes, and other specialized approaches—including optoelectrowetting, electrochemiluminescence, hyperspectral imaging, and evanescent wave spectroscopy—are also considered. The main test samples and analytes are summarized.

A sensitive and a simple method is developed for determining doxorubicin (Dox) in biological fluids without complex sample preparation. The method is based on the luminescence quenching of CdZnSeS/ZnS quantum dots (QDs) stabilized with thioglycolic acid. The luminescence quenching was investigated in model solutions and human blood plasma to determine the optimal determination parameters. The best conditions for detecting doxorubicin included QDs of an optical density A_λ=360 = 0.05 and a 25-fold plasma dilution. The method was applied to the analysis of a human blood sample. The limit of detection for doxorubicin was 0.02 μg/mL, the limit of quantification was 0.18 μg/mL, and the linear range was 0.27–4.07 μg/mL (R² > 0.96). The method demonstrated good reproducibility (RSD 1.08–1.19%). High-performance liquid chromatography with UV detection confirmed the accuracy of the method.

As an antibiotic, tetracycline (TC) is widely used and plays an important role in anti-infection treatment, so the quantitative detection of TC is of great significance. The purpose of this research is to develop a novel synthesis of silver nanoclusters stabilized with non-thiol small molecules and their application in the detection of tetracycline. Silver nanoclusters (AgNCs) were synthesized under optimized conditions using Acid Red 94 as a stabilizer, silver nitrate solution as the raw material, and sodium borohydride as the reducing agent. The optimal excitation wavelength of the synthesized AgNCs was 330 nm, and the optimal emission wavelength was 435 nm. It was found that TC could significantly quench the fluorescence of the synthesized AgNCs. The quenching value (ΔF) of the fluorescence intensity of the AgNCs has a good linear relationship with the TC concentration in the range of 10.0–50.0 μmol/L, and the detection limit was 2.3 μmol/L. Therefore, a method for TC detection was established, which was further verified by the spiked recovery method in water samples. The spiked recovery rate ranged from 101.7 to 103.8%, indicating that the established method has potential application value for the quantitative detection of TC in water samples. Additionally, a visual quantitative detection method for TC was achieved based on smartphone and colorimetric analysis software using AgNCs as fluorescent probes.

A review of publications on the development and improvement of methods for determining ricin and saxitoxin using various combinations and modifications of biochemical and immunospecific methods and also liquid chromatography–mass spectrometry is presented. Attention is focused on the importance of the choice of an analytical strategy and the optimization of sample preparation procedures and operation modes of analytical instruments. Published data on the selection of characteristic markers and methods for their determination are summarized.

The paper presents procedures for the direct analysis of table wines by microwave induced plasma optical emission spectrometry (MIP OES) and inductively coupled plasma optical emission spectrometry (ICP OES) using matrix matched reference standards. K, Na, Ca, Mg, B, Si, Al, Fe, Cu, Mn, Ba, Sr, Li, and Zn are quantified from a single dilution with an relative standard deviation of no more than 10% (n = 2). The range of constant analytical signals upon varying the concentrations of potassium, alcohol, and sucrose during an MIP OES analysis is determined. No reduction in the background signal is demonstrated upon replacing nitrogen with air in the intermediate gas flow, and improved analytical performance is demonstrated using yttrium as an internal standard in MIP OES. The results are confirmed by capillary zone electrophoresis, spike experiments, and a comparison of the results of ICP OES and MIP OES analyses.

With the increasing variation of marketed food products and multivitamins containing vitamin C (VC) as an important nutrient, the nutritional value of vitamin C has been one of the major concerns. Vitamin C is an important antioxidant and one of the most investigated water-soluble vitamins, found in fruits, vegetables, and beverages. Its use is limited because of its unstable chemical properties (oxidation and loss) during processing and storage, which makes it an important quality indicator in different food matrices and drugs. The biggest challenge in the utilization of vitamin C is to maintain its stability and improve its quality and quantity in the targeted samples. Hence, the availability of accurate and precise methods of analysis becomes a key assurance of the scientific community. The complexity of sample matrices and the instability of VC pose a great challenge in the accurate quantification of VC. Therefore, it requires consumer awareness, including concerned divisions such as food processors, authorities, quality control agencies, drug and food chemists, and the general public. This review presents high-performance liquid chromatographic methods from published papers focused on the analysis of VC in fruits, vegetables, beverages, and pharmaceutical formulations. Also, a brief introduction about VC and its derivatives, stability, chemical characteristics, sample preparation, and extraction in different food matrices and multivitamins is discussed, since these efforts can contribute to the accurate analysis of VC.

Dialdehydes are predominantly used as disinfectants, as these compounds are characterized by a broad spectrum of antimicrobial activity. Of monoaldehydes, formaldehyde is used to a limited extent because of its higher toxicity. This paper describes the conditions for the simultaneous derivatization of formaldehyde, glyoxal, glutaric aldehyde, and orthophthalic aldehyde with 2,4-dinitrophenylhydrazine. The reaction is carried out in an acetonitrile−methanol mixture at 50°C in an ultrasonic bath using trifluoroacetic acid as a catalyst. The best separation of the mixture components is achieved on a C18 column in a gradient elution mode with acetonitrile and an acetate buffer solution (pH 5.4) at variable flow rates. The linearity range for formaldehyde is 2.51 to 20.0 mg/L, for glutaraldehyde 4.92 to 21.9 mg/L, for orthophthalaldehyde 1.98 to 6.94 mg/L, and for glyoxal 2.00 to 10.0 mg/L. The limits of detection for formaldehyde, glyoxal, glutaraldehyde, and orthophthalaldehyde are 0.453, 0.177, 0.967, and 0.760 mg/L, respectively. The developed procedure was successfully applied to the simultaneous determination of aldehydes in disinfectants.

This study introduces two innovative analytical methods for the sensitive determination of cefixime trihydrate (CEF) in pure and commercial dosage forms: a spectrophotometric method utilizing a chromogenic reaction with Coomassie brilliant blue and a turbidimetric approach based on colloidal complexation with sodium phosphotungstate. The spectrophotometric method relies on the formation of a red chelate complex (λ_max = 517 nm) under optimized alkaline conditions (0.05 M NaOH), demonstrating a linear range of 40–400 µg/mL, with limits of detection (LOD) and quantification (LOQ) of 0.91 and 2.77 µg/mL, respectively. The turbidimetric method quantifies CEF via light scattering (600 nm) of colloidal aggregates, achieving a linear range of 3–55 µg/mL, an LOD of 4.80 µg/mL, and an LOQ of 14.45 µg/mL. Both methods were rigorously validated according to International Council for Harmonisation/U.S. Food and Drug Administration guidelines, exhibiting excellent precision (relative standard deviation < 2%), accuracy (recoveries: 96.5–99.8% for spectrophotometry; 85.5–96.6% for turbidimetry), and specificity against excipients and degradation products. Statistical validation (t-test, F-test) confirmed equivalence to high-performance liquid chromatography (p > 0.05). The spectrophotometric method offers superior sensitivity and precision, while the turbidimetric approach provides rapid, cost-effective analysis. These validated methods serve as robust alternatives to chromatographic techniques, enhancing accessibility for pharmaceutical quality control in diverse settings.

Sample preparation is a pressing issue in the quantitative analysis of natural wet soil samples for volatile petroleum hydrocarbons. The drying of soil to an air-dry state resulted in the loss of the most volatile hydrocarbons, while analysis of wet natural soil without sample preparation did not allow for complete extraction of petroleum products, and this led to underestimated results of the analysis. Currently available methods that make it possible to completely extract petroleum hydrocarbons are time consuming. The results of analysis are also affected by the sample weight of wet soil used for a single analysis and the number of repeated sample examinations. In this work, we investigated the possibility of using anhydrous sodium sulfate as a drying agent for the analysis of wet natural soil contaminated with diesel fuel. To determine the completeness of petroleum product extraction from wet soils, we compared sample preparation procedures with soil dying to an air-dry state and drying with sodium sulfate and also the analysis without sample preparation. The possibility of increasing the accuracy and precision of the analysis was assessed by extracting diesel fuel from 2-, 10-, and 15-g portions of model contaminated sand and wet natural soil. Each measurement was performed in two, five, and seven repetitions. It was found that chemical drying of wet soil with anhydrous sodium sulfate led to the most complete extraction of oil products from wet soil, and the use of 15-g samples and seven repeated measurements resulted in an increase in the accuracy of the analysis.