Analytical Methods最新文献

Compact, low-cost and cryogen-free benchtop nuclear magnetic resonance (NMR) spectrometers have become an attractive option for analysing complex biological mixtures. The implementation of spectral simplification methods such as pure shift spectroscopy is particularly important to circumvent the ubiquitous peak overlaps that occur due to the limited resolution of compact instruments. Pure shift (PS) strategies consist of eliminating the signal multiplicity induced by the homonuclear J-couplings observed in 1D ¹H NMR spectra, thereby simplifying the spectral information. This paper provides an analytical evaluation of optimised pure shift spectroscopy pulse sequences for the analysis of metabolite mixtures on a recent benchtop NMR spectrometer. Six PS pulse sequences were carefully evaluated, based on three families of PS techniques: 1D projections of 2D J-resolved spectra, Zangger–Sterk (ZS) and PSYCHE. The methods were evaluated in terms of resolution, sensitivity, spectral purity and repeatability. Among the strategies we explored, 1D projections of 2D J-resolved double-echo (J-RES DE) spectra, combined with an improved processing strategy, appeared to offer the best compromise based on these analytical criteria. The potential of this method was illustrated on a complex sample from the food industry and enabled key metabolites to be detected with improved resolution and sensitivity, showing that PS NMR could be used for a rapid (22 minutes) profiling of complex metabolite mixtures on a benchtop NMR spectrometer.

People of all ages may suffer from asthma. According to recent research, those who have poorly controlled asthma may be more susceptible to hospitalization and severe symptoms from any respiratory infection, particularly severe ones like the COVID-19 and human metapneumovirus (HMPV) viruses, which could result in the death of these critically ill people. Therefore, a study of the mixture of indacaterol acetate and mometasone furoate which is used in the new remarkable anti-asthmatic Breezhaler will produce substantial gains for the scientific field. A binary blend of (INDA) indacaterol acetate (1.00–30.00) μg mL⁻¹, and (MOM) mometasone furoate (1.00–40.00) μg mL⁻¹ was estimated over these ranges using six sensitive, neoteric, rapid, frugal, universal, and explicit spectrophotometric methods using the most satisfactory green solvent: ethanol. These methods are the dual wavelength method, ratio subtraction method, factorized absorbance difference method, advanced absorbance subtraction method, derivative ratio method, and derivative amplitude factor method. These procedures have been sensitively and effectively utilized for the analysis of INDA and MOM in commercial Breezhaler capsules with multiple ratios for the first time with low LOD (0.186 and 0.172) and LOQ values (0.565 and 0.520) for INDA and MOM, respectively, superior to those in other published spectrophotometric work, and they were validated in accordance with ICH specifications. Additionally, they delivered 98–102% recovery percentages and showed RSD% of less than 2 for the studied drugs, confirming their specificity. Ecological aspects of the developed work were evaluated and gave satisfactory results using several evaluation tools [such as NEMI, Eco-Scale (=93), GAPI, AGREE (=76)] for the greenness aspect, RGB (=96.3) for the whiteness aspect, and BAGI (=90) for the blueness aspect. Additionally, an environmental assessment and statistical comparisons were made using Student's t-test and the F-test with the published HPLC method and those methods currently in use.

Cytokinin (CK) is a type of hormone that exists widely in plants and plays a significant role in promoting cell proliferation and division. Developing a rapid and sensitive method for the detection of trace CKs remains challenging. Microporous organic networks (MONs) are novel materials widely used in sample preparation owing to their excellent extraction performance. Therefore, a dispersive solid phase extraction method based on carboxylated microporous organic networks (MON-2COOH), combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the detection of four CKs was developed. Upon introducing a carboxyl group into pure MON, the MON-2COOH material had excellent stability, high porosity, and a good dispersion effect, and provided more interaction sites to achieve good adsorption of target compounds. Under the best conditions, the established dSPE-UPLC-MS/MS method had the advantages of low adsorbent dosage (2 mg), low detection limit (1.0–10.0 pg mL⁻¹) and good reproducibility (RSD ≤ 6.54%, n = 5). Synergistic extraction mechanisms involving π–π, hydrogen bonding and hydrophobic interactions were elucidated using both density functional theory calculations and experimental data. This work also confirmed the feasibility of functionalized MONs as satisfactory adsorbents for the enrichment of small organic compounds.

A thorough understanding of lignin's fundamental chemistry in lignocellulosic materials is essential for maximizing the efficiency of biorefineries. Thioacidolysis, followed by gas chromatography-mass spectrometry (GC-MS), has emerged as a reliable method for quantifying uncondensed monolignols, which are linked by labile aryl ether bonds within lignin network. However, the lack of commercially available pure thioethylated lignin monomers for GC analysis poses a challenge. This necessitates a multi-step synthesis process, which may not be feasible for all laboratories. We propose a novel approach that utilizes readily available phenolic lignin model dimers to establish a calibration curve for thioacidolysis quantification. These dimers, guaiacylglycerol-β-guaiacyl ether (GGE) and syringylglycerol-β-guaiacyl ether (SGE), upon thioacidolysis, yield thioethylated non-condensed guaiacyl (G) and syringyl (S) monomers. The GC-MS responses of these monomers are compared to those of bisphenol E, an internal standard (IS) to generate the calibration curve. This methodology exhibits excellent performance characteristics and was successfully employed to determine the thioethylated monomer contents and calculate of S/G ratios in three representative biomasses: aspen, barley straw, pine, and their organosolv lignin extracts.

Gunshot residue (GSR) consists of inorganic and organic components released during firearm discharge. Understanding the generation, transport, and settlement of these residues is essential to assess exposure risks and answer questions of forensic interest. Since GSR is prone to depositing in the vicinity of a firing event, its presence on a person of interest is meaningful to evaluate hypotheses about who discharged a firearm or if GSR was acquired by alternative means such as indirect transfer, being a bystander, or passing through the area shortly thereafter. However, the complexity of GSR production and variable dispersion makes its interpretation challenging. This study employs a novel multi-sensor approach to enhance the current understanding of GSR deposition, transference, and persistence. First, a particle counting/sizing system and inexpensive custom-made atmospheric samplers measure the population of airborne particles before, during, and after the firearm discharge. Second, high-speed videography and laser sheet scattering reveals visual and qualitative information about the flow of GSR under various experimental conditions. Finally, SEM-EDS and LC-MS/MS permit the confirmation of the elemental and chemical makeup of residues. This study estimates (a) how IGSR/OGSR are produced during a firing event using various firearms and ammunition, (b) how long it takes to settle on surfaces located at various distances from the firing location, and (c) direct and indirect deposition in indoor, semi-enclosed, and outdoor environments. The combination of these analytical tools provides breakthrough knowledge in forensics and other disciplines where airborne exposure is central, such as environmental sampling and indoor air quality.

Neuroendocrine tumor (NET) is a rare and heterogeneous tumor with an increasing incidence, which is often misdiagnosed and frequently presents with distant metastases at the time of diagnosis. Chromogranin B (CgB) is not influenced by other diseases or drug factors, such as proton pump inhibitors (PPIs), and is therefore expected to serve as a complementary biomarker to improve the early diagnosis of NET. However, the detection sensitivity of CgB urgently requires improvement. In this study, a highly sensitive ECL immunosensor was designed for the detection of CgB. Graphdiyne quantum dots (GDY QDs), synthesized via the hydrothermal treatment of graphdiyne (GDY) nanosheets, exhibited good biocompatibility and a high electrochemiluminescence (ECL) quantum yield (Φ_ECL = 218.5%) when using K₂S₂O₈ as a co-reactant. With remarkable conductivity and a large surface area, Au NPs effectively loaded a high amount of GDY QDs, thereby enhancing the ECL response. Therefore, the developed ECL immunosensor showed exceptional analytical performance for CgB detection, demonstrating excellent linearity over a range of 10 fg mL⁻¹ to 100 ng mL⁻¹, with a limit of detection as low as 1.84 fg mL⁻¹ (S/N = 3). Moreover, this immunosensor could detect CgB levels in clinical serum and functioned synergistically with enzyme-linked immunosorbent assay (ELISA). This work expands the application of GDY QDs in ECL biosensors while also providing a highly sensitive detection method for CgB.

An iron-based metal organic framework (Fe-MOF) constructed using terephthalic acid as an organic linker was synthesized and characterized for its implementation in a dispersive solid-phase extraction (dSPE) procedure. This strategy was combined with a flame atomic absorption spectrophotometry (FAAS) system and employed for the preconcentration and trace level detection of copper in lion's claw tea samples. Under optimal conditions, the Fe-MOF based dSPE-FAAS method achieved a limit of detection (LOD) of 2.0 μg L⁻¹ and a limit of quantification (LOQ) of 6.7 μg L⁻¹. The determination coefficient (R²) was found to be 0.9984 for the concentration range of 5.0–100 μg L⁻¹, indicating superior linearity for the developed Fe-MOF-dSPE-FAAS method. The sensitivity was enhanced by 88.2 folds. Moreover, acceptable recovery percentages at five different spiked levels within the concentration range of 7.5–75 μg L⁻¹ for the lion's claw tea sample matrix were achieved through the application of a matrix matching strategy.

The detection of intracellular copper ions is crucial for advancing biomedical research and enhancing disease diagnosis. In this study, blue emissive carbon dots (B-CDs) were successfully synthesized using raspberry as the carbon source through a simple hydrothermal method. Characterization techniques combined with theoretical calculations confirmed that the fundamental structural unit of B-CDs is a twelve-membered aromatic ring rich in oxygen and nitrogen functional groups. The B-CDs exhibited high selectivity for Cu²⁺, showing a strong linear response in the concentration range of 0 to 150 μM, with a detection limit of 0.39 μM. Zeta potential and hydrodynamic size measurements indicated that the B-CDs interact with Cu²⁺via electrostatic forces. Further studies revealed that the fluorescence quenching of B-CDs in the presence of Cu²⁺ is primarily due to a dynamic quenching process. Moreover, B-CDs were successfully applied to detect intracellular Cu²⁺. These findings not only show significant potential of B-CDs in fluorescence sensing but also provide valuable insights for the design of efficient carbon-based sensors.

The modulation of 17β-estradiol (E2) level, even in trace amounts outside the normal range, plays a critical role in diagnosing and treating various diseases in females. This work presents a novel, simple, and highly sensitive method for E2 detection based on the designed repetitive-loop aptamer. The method is based on the different fluorescence intensities of SYBR Green I (SGI) to intercalate the DNA aptamer structures, which are changed upon interacting with E2. Among the designed aptamers containing 1–5 loop structures (designated as O1–O5), the O5-aptamer exhibited the highest E2 interaction and was employed to construct the O5-aptasensor. Under optimal conditions, the aptasensor displayed excellent sensitivity, with a linear detection range of 1–200 pM, a limit of detection (LOD) of 1.34 pM, and a limit of quantification (LOQ) of 4.48 pM. Its LOD is 13.5 folds lower than that of the L1-aptasensor. The O5-aptasensor specifically detected E2, distinguishing it from structurally similar compounds such as progesterone, genistein, diethylstilbestrol, bisphenol A, and chloramphenicol. Furthermore, the O5-aptasensor accurately detects E2 spiked in artificial urine and human serum samples, with recovery rates ranging from 98.73% to 109.00%, and relative standard deviations below 8%. The O5-aptasensor was tested on blood serum samples from seven hospital patients, and its performance was comparable to that of the hospital analysis for E2 measurement. These findings highlight the potential of the O5-aptasensor as a highly sensitive platform for clinical E2 detection, offering a viable alternative to existing methods.

The screening of effective active ingredients from traditional Chinese medicine (TCM) formulas is currently a key focus of research. In this study, a multichannel microperfusion cell-capture system utilizing human hepatocellular carcinoma HepG2 cells was established and used to screen for anticancer active ingredients in the ancient formula Huangqisan. A polypropylene solid film carrying HepG2 cells was used as the cell-capture platform, and a multichannel microperfusion system was utilized for perfusion, enabling the screening of multiple ingredients' activities. This study optimized the main factors influencing the screening results and conducted a methodological examination under the optimal screening conditions. The method was coupled with high-performance liquid chromatography (HPLC) to analyze and identify the anticancer ingredients in Huangqisan. The optimal conditions were determined as follows: use of a polypropylene film as the cell support, a 7 mL sample phase solution (3 μg mL⁻¹) for perfusion, and a screening duration of 30 min. After screening, eight anticancer active ingredients in Huangqisan, namely, calycosin, calycosin glycoside, formononetin, ononin, genistein, isorhamnetin, puerarin, and morin, were preliminarily determined by comparing their chromatographic retention times and peak areas with standard substances. The cell fishing factor (CFF) of these ingredients ranged from 1.1 to 19.8. In summary, the use of a multichannel microperfusion cell-capture system combined with HPLC enabled the screening of the anticancer active ingredients in Huangqisan. This method thus provides a new approach for screening complex TCM matrices and holds promising prospects for future development.