Journal of Analytical Chemistry最新文献

A novel solid-phase extraction procedure was developed for the preconcentration and measurement of cadmium in plant leaves (lettuce and tobacco) and water samples utilizing flame atomic absorption spectrometry. This proposed method involves the in situ formation of an insoluble ion-pairing salt to be used as a sorbent. Cetyltrimethylammonium bromide was utilized as a cationic surfactant, and perchlorate was added as an ion-pairing agent. Cadmium(II) ions were selectively extracted after forming a complex with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. The variables were optimized, and method validation was performed. The limit of detection and limit of quantification were, respectively, 0.31 and 1.1 μg/L. With a preconcentration factor of 40 and a relative standard deviation of 2.6%, the method demonstrates promise for detecting low levels of cadmium. The monitoring of cadmium in real samples was successfully carried out using the suggested approach.

Sample preparation of naturally occurring matrices necessitates the development of highly sensitive and selective methods for the extraction and preconcentration of biologically active compounds. Smart materials are highly promising in this area and are selected for solving for specific analytical tasks. This review examines the main categories of such materials, including ionic liquids, eutectic solvents, nanomaterials, metal-organic frameworks, covalent organic frameworks, and molecularly imprinted polymers. It highlights their unique properties and provides specific examples of their application to chemical analysis between 2020 and 2025. The article discusses the use of smart materials in the analysis of biological fluids and environmental samples, available microextraction techniques, and subsequent quantification methods. It emphasizes the advancements achieved in comparison to the previously established approaches.

The results of microextraction separation and ICP–MS determination of inorganic arsenic species in natural waters are presented. The necessity of the separate quantification of analytes is justified, as arsenites exhibit toxicity dozens of times higher than arsenates. Separation was performed by the selective liquid–liquid microextraction of As(III) complexes with sodium diethyldithiocarbamate into an organic phase. Extraction conditions were optimized to achieve the highest recovery of As(III) complexes at approximately 95%. The As(III) complexes with sodium diethyldithiocarbamate were extracted into the organic phase using carbon tetrachloride as an extractant and methanol as a dispersant. Matrix effects of elements on analyte extraction from water were eliminated by performing a double microextraction of the analytes. Total inorganic arsenic and As(V) concentrations were determined by an ICP–MS analysis of the original water samples and their aqueous extracts obtained after the separation of inorganic arsenic species. The concentration of As(III) in water was calculated as the difference between total arsenic and As(V) concentrations. The limits of detection for As(III) and As(V) in water were equal, at 0.010 μg/L, within a linearity range of 0.05 to 100 μg/L, R² = 0.9998. The accuracy of the determination of inorganic arsenic species in water was confirmed by the standard addition method. The analytical procedure was validated using model waters and real samples of drinking and natural waters.

This study investigates the distribution and quantification of phenolic compounds in different tissues (juice, pulp, and peel) of six Satsuma mandarin (Citrus unshiu) varieties cultivated in Croatia. Narirutin and hesperidin were the dominant flavonoids in mandarin juice and pulp, with the highest concentrations observed in the “Okitsu” variety. Peel samples exhibited a higher flavonoid content, particularly hesperidin and polymethoxylated flavones, such as nobiletin and tangeretin. Extractable and bound phenolic acids, including ferulic, caffeic, and p-coumaric acids, were quantified. The “Okitsu” variety showed the highest levels of most phenolic acids. The optimized high-performance liquid chromatography method demonstrated high precision and sensitivity, enabling efficient quantification of 18 phenolic compounds. This study provides valuable insights into the phenolic composition of Satsuma mandarins, contributing to citrus quality assessment, dietary applications, and sustainable utilization of citrus waste.

Products of oxidative damage to nucleic acids are considered as relatively stable biomarkers in the diagnosis of negative consequences of oxidative stress. The concentrations of biomarkers of oxidative degradation of DNA (8-hydroxy-2'-deoxyguanosine, 8-OHdG) and RNA (8-hydroxyguanosine, 8-OHG) in biofluids increased when the body was exposed to toxic compounds, radiation, and other negative factors associated with oxidative stress. Urine is considered as a priority matrix for biomonitoring the consequences of oxidative stress because of noninvasive sampling and higher concentrations of the target analytes. We developed a procedure for the combined determination of 8-OHdG and 8-OHG in urine using HPLC–MS/MS analysis. A structurally similar exogenous compound, 8-[(1-hydroxybutan-2-yl)amino]-1,3,7-trimethyl-1-purine-2,6(3H,7H)-dione, was selected as an internal standard. The measurement range from 1 to 50 ng/mL was set for both analytes. A solid-phase extraction procedure on a hydrophilic–lipophilic balance (HLB) sorbent in the analyte retention mode was optimized to prepare biological samples for analysis. With the use of high-resolution HPLC–MS/MS technique, the error of analysis did not exceed 25% over the entire analytical range. A total of 130 urine samples of chemical plant workers aged 20 to 70 years without diagnosed systemic diseases were analyzed. The 8-OHdG and 8-OHG contents of the urine samples ranged from 1 to 20 and from 2 to 12 ng/mL, respectively. The dependence of the concentrations of both biomarkers in urine on the age of the workers was established.

Magnetic hypercrosslinked polystyrene (MHCPS) is proposed for the group adsorption and preconcentration of quinolones. The conditions for magnetic solid-phase extraction are selected as follows: 25 mL of solution (pH 6), sorbent mass 20 mg, and sorption time 20 min. The analytes have been desorbed with 2 mL of methanol. It is shown that the sorbent provides the quantitative extraction of all 23 studied compounds not only from aqueous solutions, but also from milk, bypassing the deproteinization stage. The determination is carried out by HPLC-tandem mass spectrometry using matrix calibration. The limits of detection and determination for quinolones are 0.012–0.12 and 0.04–0.4 μg/L, respectively, which are below their maximum residue levels in milk.

Prospects for the use of imidazolium ionic liquids (ILs) as extractants of sex steroid hormones (estrogens and androgens) in microextraction methods (dispersive liquid–liquid microextraction, DLLME, and magnetic solid-phase microextraction, mSPME) are identified. The key parameters of DLLME using C₆MImNTf₂ ionic liquid that affect extraction efficiency are optimized using the design of experiments technology. High recoveries (88–99%) are achieved. An approach of dynamic IL immobilization on the surface of magnetic nanoparticles (MNPs) for the extraction of steroids under mSPME conditions is proposed. Two types of MNP pre-coating are studied: hydrophilic based on silica and hydrophobic with oleic acid. The capabilities of C₈MImBF₄ ionic liquid as a MNP surface modifier for the efficient extraction of steroids are revealed. Optimum conditions provided high degrees of recovery (83–97%), with an exception of estriol (60%). The limits of detection are 0.26–1.29 ng/mL. Limitations of the method related to the partial removal of IL from the surface of NPs are revealed; they reduce the reproducibility of the results for estriol.

Specific features of the preconcentration and determination of polycyclic aromatic hydrocarbons (PAHs) in humus-rich soils by gas chromatography–mass spectrometry (GC–MS) are studied. The QuEChERS technique and dispersive liquid–liquid microextraction (DLLME) were employed to extract PAHs from soils using acetone and binary extractants of various compositions, including acetonitrile–dichloromethane, acetonitrile–acetone, acetone–hexane, acetone–chloroform, acetone–dichloromethane, and ethyl acetate–dichloromethane. Recoveries of low- and medium-molecular-weight PAHs using these solvent mixtures reached approximately 100%, while the acetone–dichloromethane mixture yielded over 90% recovery for high-molecular-weight PAHs. Under optimized GC–MS conditions with QuEChERS extraction, the limits of quantification (LOQ) for fluoranthene, pyrene, chrysene, and triphenylene reached 5 µg/kg, and for the remaining PAHs, 10 µg/kg in humus-rich soils. It was shown that the reliable GC–MS determination of lower concentrations of PAHs requires both the elimination of the matrix effect and the preconcentration of the analytes. The sequential application of QuEChERS and DLLME techniques enabled a decrease in the limits of quantification by GC–MS to 1.8 µg/kg for fluoranthene, pyrene, chrysene, and triphenylene, and to 3.5 µg/kg for the remaining PAHs. The optimized procedure for PAH determination in humus-rich soils was validated using real chernozem samples.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus that has been identified as the causative agent of an ongoing global pandemic of acute respiratory distress syndrome, coronavirus disease 2019. Ranked as one of the top priorities is developing an accurate, reliable, and affordable laboratory diagnostic test for pathogen detection to facilitate disease tracking. In this study, a multiplex-based assay to detect SARS-CoV-2 using four primers/probes to amplify regions of the spike (S), nucleocapsid (N), and envelope (E) protein-coding genes, along with amplifying region of the 3' untranslated region (UTR) was designed and developed. To provide accurate detection of different SARS-CoV-2 variants, an in silico design and validation pipeline was utilized. These included multi-sequence alignments with Clustal Omega, specificity verification by the Basic Local Alignment Search Tool (primer-BLAST), and computational performance verification using Biopython. The primers and hydrolysis probes designed were experimentally tested against more than two million SARS-CoV-2 genome sequences obtained from the National Center for Biotechnology Information Virus Database, with >97% specificity across 2200 lineages, including all of the significant variants of concern and variants of interest. The experimental validation phase included synthetic SARS-CoV-2 constructs and ribonucleic acid samples from nasopharyngeal swabs of 20 patients, including both symptomatic and asymptomatic cases. The assay displayed 100% sensitivity and specificity, with the limit of detection as low as 10 copies/mL, which surpassed the detection limits of some commercially available reverse transcription quantitative polymerase chain reaction (RT-qPCR) kits. Amplification efficiency was optimized for all targets, ranging from 94.92% for the N gene, 98.84% for the S gene, 81.75% for the E gene, to 82.14% for the 3′UTR genes. Assay selectivity was verified by cross-reactivity against common respiratory viruses—SARS-CoV-1, Middle East respiratory syndrome coronavirus, Influenza A/B, and human coronaviruses (HCoV-229E, HCoV-NL63, HCoV-OC43, and HCoV-HKU1)—and no off-target signal was observed. The ability to detect multiple genomic regions renders the assay resilient to mutation-based primer mismatch, making it extremely suitable for clinical diagnostics, epidemiological surveillance, and variant monitoring.

The chromatographic retention of alcohols, ketones, alditols, and carbohydrates on a cation exchanging column (200 × 4.6 mm, Sevko AA) packed with sulfonated poly(styrene-divinylbenzene) with a crosslinking degree of 10% and a particle diameter of 7 μm saturated with various counterions (H⁺, Ca²⁺ and La³⁺) is studied in the ligand exchange chromatography version. The sorbent in the Ca²⁺ form shows higher retention times and selectivity in the separation of carbohydrates and ethylene glycols. The sorbent in the La³⁺ form provides a strong retention and a better selectivity for the separation of alditols. A possibility of using this column for determining carbohydrates in food products (juice, honey) using refractometric detection is shown.