Journal of Analytical Chemistry最新文献

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.

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.