Analytical Methods最新文献

The development of a stable, high-precision and batch ion-adsorption rare earth element detection method is highly anticipated in the delineation and evaluation of the mining value of rare earth element mines. In this study, a novel mixed extractant of ammonium sulfate + ammonium citrate + aceto-sodium acetate buffer was used to significantly improve the extraction efficiency of rare earth elements. Following a series of parameter optimizations, an off-line internal standard addition method and the collision mode of the inductively coupled plasma-mass spectrometer were used to improve the detection efficiency for batch samples, effectively eliminating oxide interference between the rare earth elements and improving the detection accuracy. The detection limit for ion-adsorption rare earth elements was 3.4 μg g^-1 and the detection range was 12-8000 μg g^-1. More importantly, the spiked and recovery experiments carried out in multiple laboratories with internal quality control samples show that the relative deviation was -5.61 to 3.79%, which indicates that the method has sufficient stability. Establishment of this method will help to improve the comprehensive utilization efficiency of rare earth resources and provide important support for rare earth element mining.

Nanozymes are nanomaterials with catalytic properties similar to enzymes and offer advantages over natural enzymes such as lower cost, ease of storage, and convenience for large-scale preparation. Thus, they have received increasing attention and are extensively applied in fields such as chemistry, sensing, food, environment, and medicine. Herein, a hemin-derived nanozyme (Hemin-CDs) was prepared using hemin as the precursor and used to substitute the natural horseradish peroxidase (HRP) for colorimetric detection. The prepared Hemin-CDs exhibit excellent water dispersibility, stability and superior peroxidase-like activity. They catalyze the oxidative coupling of colorless 4-aminoantipyrine (4-AAP) with N-ethyl-N-(2-hydroxy-3-sulfopropyl)-3-methylaniline sodium salt (TOOS) in the presence of H₂O₂, forming a purple quinone diimine dye with an absorption peak at 554 nm, which enables the quantification of H₂O₂ by measuring the absorbance. Quantitative detection of glucose was further demonstrated under physiological conditions. The detection of H₂O₂ and glucose takes only 10 minutes, with linear ranges of 1-150 μM and 2.5-300 μM, and LODs of 0.867 μM and 1.026 μM, respectively. Glucose in human serum was successfully detected with satisfactory recoveries (87.5-104.0%). Furthermore, a test strip was developed, and a smartphone was utilized to recognize the color of the test position, enabling rapid and accurate quantification of glucose concentrations within 5 minutes, which promises to enhance the accessibility and convenience of glucose testing.

Aflatoxins (AFs) are some of the most important mycotoxins or fungal toxins that cause contamination of food products and are considered a threat to human and animal health. An efficient Cu/β-cyclodextrin/reduced graphene oxide nanocomposite (Cu/β-CD/rGO) has been prepared and applied as a new solid-phase extraction adsorbent for the separation and preconcentration of four AFs (B₁, B₂, G₁, and G₂) using high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The successful synthesis of the prepared nanocomposite was confirmed using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The impacts of pH, amount of adsorbent, sample volume, desorption solvent volume, and salt concentration on the recovery of AFs were precisely investigated and optimized by central composite design (CCD). Under the optimal conditions, the introduced method demonstrated good linearity in the range of 0.4-5.4, 0.08-1.08, 0.4-5.4, and 0.08-1.08 ng g^-1 for AFs B₁, B₂, G₁ and G₂, respectively. The limits of detection and quantification for the four AFs were obtained in the range of 0.06-0.53 and 0.20-1.62 ng g^-1, respectively. The accuracy of the method was evaluated using recovery measurements in spiked real samples such as rice, bean, and ginger samples, and satisfactory recoveries were obtained in the range of 83.5-109.0% with good precision (RSDs between 2.4 and 8.6%). The results of this research revealed that our developed method is sensitive, highly effective, and convenient to perform for the trace analysis of AFs in different real samples.

Fourier self-deconvolution is an effective method for resolving overlapping spectra. However, the selection of the half-width for the deconvolving function is often subjective, which can lead to either excessive convolution or insufficient resolution enhancement. Additionally, ion mobility peaks exhibit tailing effects, which may be misinterpreted as new peaks when the deconvolving function is modelled with a Gaussian function. This paper proposes an improved Fourier self-deconvolution method based on continuous wavelet transform. The proposed method determines the signal half-width by calculating the horizontal distance between the peaks and troughs of the wavelet coefficients, offering a more accurate estimation. Furthermore, an asymmetric function is employed to optimize the peak shape of the deconvolving function, significantly reducing the likelihood of peak misidentification. The effectiveness of the proposed method is validated using both simulated and experimental ion mobility spectrometry data. Experimental results demonstrate that the proposed method effectively enhances peak resolution and resolves overlapping peaks. Moreover, compared with other peak segmentation algorithms based on Fourier self-deconvolution, the proposed method demonstrates lower parameter estimation error and higher computational efficiency, particularly for severely overlapping peaks.

The transformation of renewable feedstocks into aromatic chemicals holds immense potential for advancing a green, low-carbon economy and fostering sustainable development. Herein, we present a novel approach for the conversion of isoeugenol, a renewable lignin derivative, into the valuable flavoring agent vanillin, utilizing ozone as an environmentally benign oxidant. The process optimization was significantly enhanced by the integration of in situ Attenuated Total Reflectance Infrared (ATR-IR) monitoring. The introduction of H₂O not only accelerated the decay of carbonyl oxides (Criegee intermediates) but also mitigated safety hazards stemming from the vigorous decomposition and heat release of secondary ozonides. Compared to the conventional Thin Layer Chromatography (TLC) method, ATR-IR monitoring demonstrated superior sensitivity and precision in determining the reaction endpoint, leading to a remarkable vanillin yield of 96.86% upon complete conversion of isoeugenol. Additionally, a comparative assessment of the sustainability of our approach with existing methods was undertaken, and valuable recommendations for safety assessments were provided to ensure the inherent safety of chemical engineering reactions. The present study serves as a pioneering effort in facilitating the implementation of a scalable, economically feasible and environmentally sustainable strategy for biomass flavor production, while contributing to the broader adoption of in situ spectroscopic technology within the larger economy.

Correction for 'Establishment and characterization of noro-VLP measurement by digital ELISA' by Takema Hasegawa et al., Anal. Methods, 2024, 16, 7089-7094, https://doi.org/10.1039/D4AY01012D.

Food quality is a crucial issue for producers and consumers, either dealing with commodities according to basic standards or with top quality products. Among the parameters contributing to quality, the place of origin is considered to be one of the most relevant, especially for protected denomination of origin and protected geographical indication foods, PDO and PGI, respectively. These labels have been designed by the EU to protect and valorise high quality foodstuff produced in limited areas and to ensure higher incomes to farmers. Such economic interest has prompted the use of several analytical techniques for the traceability issue. Here we proposed the multivariate HRMAS-NMR (i.e. High-Resolution Magic Angle Spinning-Nuclear Magnetic Resonance) data analysis for the traceability of PGI Chianina meat, specifically for the semitendinosus muscle. The metabolic profile of Chianina meat assessed by HRMAS-NMR spectroscopy was analysed by means of PCA (Principal Component Analysis), PLS-DA (Partial Least Square-Discriminant Analysis) and OPLS-DA (Orthogonal Partial Least Square-Discriminant Analysis) in order to classify samples according to the geographical origin. The built models provided an excellent separation between PGI and non-PGI, and the use of the VIP (Valuable Influence on Projection) values allowed us to identify metabolites contributing significantly to classification. Specifically, we found molecules such as amino acids, carnosine, some nucleosides, and fatty acids to be responsible for the discrimination: the fatty acid profile of meat is affected by the different feeding systems, while the other metabolites are involved in the ageing process of meat (ATP degradation during post mortem and proteolysis).

Pseudomonas aeruginosa (P. aeruginosa, PA) is a rod-shaped Gram-negative opportunistic bacterium capable of causing nosocomial infections during nursing, such as burn wound infections and meningitis. However, sensitive and rapid PA detection remains a huge challenge. Herein, a new fluorescent biosensor was developed for the sensitive detection of PA using a three-way junction (TWJ) probe for specific identification and CRISPR/Cas14a1 for enhanced exponential amplification. The interaction between PA and its aptamer on a DNA TWJ structure probe triggered the migration of the double-stranded DNA branch, inducing DNA polymerase/endonuclease assisted chain displacement and the generation of single-stranded DNA sequences. The amplification products have the ability to activate CRISPR/Cas14a1, resulting in effective trans-cleavage and the subsequent release of fluorescence from the reporter probes. Under optimized conditions, the proposed biosensor was able to detect a wide range of bacterial concentrations, ranging from 10 to 10⁵ cfu mL^-1 within 30 min. The limit of detection, which is the lowest concentration that can be reliably detected, was determined to be 3.4 cfu mL^-1 according to the 3δ rule. The results of the recovery test suggest that the biosensor shows significant potential for clinical applications. The established biosensor utilizing the TWJ probe generated multiple isothermal exponential amplification and the CRISPR/Cas14a1 biosensor is an excellent platform for rapidly detecting pathogenic bacteria in postoperative infection.

In this study, we present three different approaches for the colorimetric detection of Ni²⁺ ions using a specifically designed benzothiazole-quinoline dyad (L) synthesized via the Knoevenagel condensation reaction in high yield. The unique properties of L enable a rapid and selective response to Ni²⁺ ions, making it an ideal probe for practical applications. The probe L shows a pale yellow color under normal conditions. Upon interaction with Ni²⁺ ions, L undergoes a significant color change from pale yellow to bright orange, allowing for visual detection in semi-aqueous media. This rapid colorimetric response enables real-time monitoring of Ni²⁺ concentrations. The absorption maximum of L undergoes a bathochromic shift in the presence of Ni²⁺ ions due to ligand-to-metal charge transfer (LMCT). The probe L could form a 2 : 1 [L : Ni²⁺] stoichiometric complex, confirmed through Job's plot and ESI mass analysis with an estimated association constant of 2.61 × 10⁶ M^-2. The probe L could detect Ni²⁺ concentration down to 61 nM, 106 nM, and 129 nM via a UV-Vis spectrophotometer, smartphone-assisted RGB method, and test paper strip analysis. The binding mechanism of probe L with metal ions was studied using ¹H NMR, ESI mass spectrometry, and DFT calculations. The zeta potential analysis showed a potential of -28.38 mV for the free ligand and +12.09 mV upon complexation with Ni²⁺. More importantly, the potential application of probe L includes the quantification of Ni²⁺ ions in various water samples through all three sensing approaches.

In recent years, multifunctional cell regulation on a single chip has become an imperative need for cell research. In this study, a novel multi-functional micro-platform integrating wireless electrical stimulation, mechanical stimulation and electrical response recording of cells was proposed. Controlling cell fate by photoexcited radio stimulation of cells on photosensitive films can precisely orchestrate biological activities. This is the first report of combining hydrogenated amorphous silicon (a-Si:H) photosensitive films and a 532 nm green laser for cell stimulation and electrical response recording. Remote wireless electrical stimulation of nerve cells through photoelectric effects based on photosensitive films evoked a change in membrane potential and promoted the neurite growth and neuronal differentiation. These effects were confirmed in a cell model of the human neuroblastoma cell line. The electrical response of cells demonstrated that the photocurrent generated by laser irradiation of the photosensitive film induced a redistribution of ions inside and outside the cell. Furthermore, a mechanical stimulus was applied to cells using a probe placed above them. The chip was used as a signal output to simultaneously obtain the electrical response of cells. The ability of photosensitive films to precisely excite cellular activity offers a novel prospect for wireless electrical stimulation. This work provides a promising strategy for the design of multi-functional biological devices based on a single chip.