Journal of Analytical Chemistry最新文献

Milk is the primary nutrient essential for the growth of living beings from the postnatal period to death. Today’s world is constantly concerned with a healthy diet and what is best for them. People are increasingly interested in understanding the compositions to achieve the best results for their health. Milk is also tested to determine its fundamental components. Milk samples from different species were tested, including ovine, caprine, bovine, donkey, and human milk. This review discusses the analysis of milk and its components by liquid chromatography and its hyphenation with tandem mass spectrometry, covering various compositions, including vitamins, lipids, carbohydrates, and proteins, and the analysis of different components added to milk to improve or change its compositions, which are considered contaminants.

The analysis of exhaled breath represents a rapidly advancing field in noninvasive medical diagnostics. This method avoids invasive procedures and allows for repeated testing. Acetone in exhaled breath correlates with blood glucose levels and serves as a biomarker for diabetes. Implementing analytical systems in medical facilities for the detection of acetone in exhaled breath facilitates the timely diagnosis of pathological changes in blood glucose levels, promotes early diabetes diagnosis, and supports monitoring of therapeutic effectiveness. This study proposes a method for the rapid detection of acetone in exhaled breath using a mobile diagnostic complex based on microfluidic systems. The system includes a PIA gas microchromatograph with a thermochemical detector, a planar chromatography column, a thermostated sample collection system, and the selective capture of interfering components, all regulated by electric microvalves. Additionally, it includes an automatic dosing system with adjustable purging times, ranging from 0.1 to 5 s, and accompanying software. This procedure enables analyses within a diagnostically significant range of acetone concentrations (0.5–20 ppm) in exhaled breath for diabetes diagnosis. The total analysis time is 3 min, with a retention time of 60 s for acetone. We have tested the diagnostic complex, which allows the direct detection of acetone in exhaled breath. The capture and drying system shows no loss of the target substance and ensures the high reproducibility of the results, with deviations from the reference value not exceeding 10%. Field testing confirmed the data obtained on model mixtures. We recommend the developed mobile diagnostic complex with automatic programmable dosing and the method for the quantitative determination of acetone in exhaled breath (0.5–20 ppm) for use in clinical studies within medical institutions.

Lavandula angustifolia (lavender) is among the most practical and widely employed medicinal plants. Rosmarinic acid constitutes a fundamental constituent of lavender. This study centers around the extraction of rosmarinic acid from prepared lavender extract using hollow fiber-based liquid phase microextraction with acetonitrile as an extractant. The optimization of extraction factors, such as the initial and extraction solvent pH, and extraction time, is achieved through the application of a chemometric method. Additionally, the quantification of rosmarinic acid in samples of commercial herbal medicines is also investigated. The results obtained from the experimental design analysis revealed that the initial solvent pH had a statistically significant impact on the efficiency of rosmarinic acid extraction (p-value < 0.0001). Furthermore, the efficiency remains unaffected by the extraction time (p-value 0.5464). In order to obtain a significant value for the rosmarinic peak area as a response, the extraction solvent pH was set to 3.17, and the extraction time was set to 17.32 min. The optimized procedure demonstrated linearity in the range of 0.5 to 200 μg/g; the determination coefficient, limits of detection, and quantification were, respectively, 0.9998, 015, and 0.5 μg/g. Consequently, it was determined that each sample of the herbal medicines contained rosmarinic acid.

In this work, a magnetic porous material (Fe₃O₄@MoS₂) was facilely prepared and applied for magnetic solid-phase extraction clean-up before the determination of chlorpromazine in urine samples via high-performance liquid chromatography with ultraviolet detection. Various key factors affecting the extraction and desorption recoveries, including the amount of adsorbent, extraction time, pH, sample volume, adsorption capacity, and desorption conditions, were systematically investigated. Under optimized conditions, the calibration curve was linear over a wide concentration range of 10.00–5000 ng/mL, with a correlation coefficient of 0.9997. The limit of detection was determined to be 3.2 μg/L. Besides, recoveries for spiked urine samples at three concentration levels ranged from 97.2 to 105.8%, and the enhancement factor was 48. These results demonstrate that the proposed method is efficient and economical for the determination of chlorpromazine at trace levels in urine samples.

The possibility of establishing relationships between the distribution of total concentrations and mobile forms of the elements in vineyard soils was studied using ICP spectrometry and chemometric analysis. The authenticity of wines based on varietal and geographical characteristics was studied based on the relationships between the elemental compositions of wine, grapes, and soil from the place where the grapes grew. The nature of the supply of the elements in the soil–grape chain and the degree of absorption of mobile forms of soil elements by grape berries were also assessed using the biological absorption coefficient. Each grape variety formed an elemental image due to the individual character of assimilation of the studied elements. The concentrations of K, Rb, and Ti found in grape samples were higher than the concentrations of mobile forms of these elements in the soil regardless of the variety. Scatter diagrams of canonical values and projections of observations onto the factor plane, constructed using multivariate statistical analysis methods for element concentrations, showed that each grape variety was localized in a certain part of the plane to form groups of homogeneous objects (clusters). The contributions of elements to the grape variety discrimination model decreased in the sequence Mo, Cu, K, Ni, Ba, Ca, Pb, Li, Mg, Fe, Ti, Zn, Rb, Al, and V or, on a regional basis, Rb, Al, K, Sr, Co, Na, Pb, Ca, and Ni. The results obtained can be used to determine markers responsible for the varietal and regional affiliations of wines.

It is shown that a transition from traditional C18 (I) stationary phases with non-polar endcapping to the C10CN (II) phase, containing terminal polar groups, leads to a change in selectivity comparable to an increase in the activity of residual silanol groups in phases I. The effect was detected in the separation of isomeric monocaffeoylquinic acids. Two versions of the gradient mode are proposed using a Diasfer-110-C10CN column and water–acetonitrile components of the mobile phase acidified with H₃PO₄ for the separation of chlorogenic acids and caffeine in green coffee extracts from different manufacturers. It was shown that the proposed chromatographic method can also be used to determine trigonelline, the retention of which significantly increased in replacing phase I with phase II. The proposed method was used to differentiate the fruits of two types of coffee—Arabica and Robusta. It was found that the total amount of chlorogenic acids and caffeine is higher in Robusta coffee extracts.

Complex compounds of Cu, Ag, Pd, Pt, and Au with dithizone (diphenylthiocarbazone) were studied by surface-assisted laser desorption/ionization from nanocrystalline silicon. The study demonstrated that all investigated complexes ionize efficiently in the negative ion mode, forming molecular ions and one or more types of fragment ions. The limits of detection for the metal dithizonates were determined. A possibility of coupling laser desorption/ionization mass spectrometry with single drop microextraction for metal detection was explored. Factors affecting the concentration factor were examined, and the optimal conditions for performing single drop microextraction in gold determination were found. The limit of detection for gold is 5 pg/mL.

A contactless method is proposed for determining the mass fraction of milk fat in bottled milk by the diffuse reflectance LED at the wavelengths 365, 390, 850, and 880 nm using a smartphone and a specialized device. The analytical signal was recorded using OnePlus 10 Pro and iPhone 14 smartphones, equipped with PhotoMetrix PRO®, ColorGrab, and RGBer applications, as well as using an FTIR spectrometer for the near-IR region (4000–10 000 cm^–1). Specialized software, including TQ Analyst, The Unscrambler X, and XLSTAT, was used to process the experimental data. It was found that using all LEDs with different wavelengths simultaneously yielded results with the smallest relative deviation compared to using individual LEDs. Additionally, a slight change in the diffuse reflectance of milk through polyethylene terephthalate-based packaging was identified, which enabled contactless analysis without opening the packaging. The milk fat content of the test milk samples was evaluated using a multivariate calibration data algorithm—partial least squares regression. The relative standard deviation of the analysis results did not exceed 8%. The consistency of the analysis results was confirmed by FTIR spectroscopy in the near-IR region.

Thallium (Tl), a heavy metal, has potentially harmful effects on human health due to its extreme toxicity. The determination of Tl is critical, and thus, there is a need for the development of electrochemical sensors that can swiftly identify its presence in the environment. A one-step hydrothermal synthesis of Prussian blue (PB) was utilized to adsorb thallium and electrochemically activate PB. The structure and morphology of PB were characterized through a scanning electron microscope, X-ray energy spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The PB-modified electrode’s determination performance was optimized using the square wave voltammetry method. This included the optimization of support electrolyte, pH, deposition potential, and deposition time. Under optimal experimental conditions, the electrode demonstrated a favorable electrochemical response to thallium concentrations between 10 and 500 μg/L, with a detection limit of 1.94 μg/L. In summary, this sensor’s outcomes are satisfactory and enhance the utility of PB nanomaterials in electrochemically detecting the heavy metal Tl.

Stable electrospray generation from fused silica tips is critical for mass spectrometry, but these tips can degrade, leading to droplet formation and poor spray. A quick, cost-effective method has been developed to rejuvenate these tips, extending their usability and reducing expenses. The protocol involves sequentially rinsing pulled fused silica emitters for electrospray ionization (ESI) with acetone, water, an aqueous sodium hydroxide solution, water, and acetone again, followed by air drying. Next, the tip is dipped into a hydroxy-terminated polydimethylsiloxane solution and air dried. A final acetone rinse completes the process, which does not require disassembling the fluidic flow system or removing the nESI tip from its mount. This reconditioning not only prevents droplet formation but also restores the correct spray pattern, ensuring stable electrospray for 1–2 weeks. Tips can undergo multiple reconditionings. Although the protocol may lead to transient contaminant peaks, these diminish over 24 hours, and a list of potential contaminants is provided.