A new ion mobility (IM) spectrometer, enabling mobility measurements in the pressure range between 5 and 500 mbar and in the reduced field strength range E/N of 5-90 Td, was developed and characterized. Reduced mobility (K0) values were studied under low E/N (constant value) as well as high E/N (deviation from low field K0) for a series of molecular ions in nitrogen. Infrared matrix-assisted laser desorption ionization (IR-MALDI) was used in two configurations a source working at atmospheric pressure (AP) and, for the first time, an IR-MALDI source working with a liquid (aqueous) matrix at sub-ambient/reduced pressure (RP). The influence of RP on IR-MALDI was examined and new insights into the dispersion process were gained. This enabled the optimization of the IM spectrometer for best analytical performance. While ion desolvation is less efficient at RP, the transport of ions is more efficient, leading to intensity enhancement and an increased number of oligomer ions. When deciding between AP and RP IR-MALDI, a trade-off between intensity and resolving power has to be considered. Here, the low field mobility of peptide ions was first measured and compared with reference values from ESI-IM spectrometry (at AP) as well as collision cross sections obtained from molecular dynamics simulations. The second application was the determination of the reduced mobility of various substituted ammonium ions as a function of E/N in nitrogen. The mobility is constant up to a threshold at high E/N. Beyond this threshold, mobility increases were observed. This behavior can be explained by the loss of hydrated water molecules.Highly polar trace organic compounds, which are persistent, mobile, and toxic (PMT) or are very persistent and very mobile (vPvM) in the aquatic environment, may pose a risk to surface water, ground water, and drinking water supplies. Despite the advances in liquid chromatography-mass spectrometry, there often exists an analytical blind spot when it comes to very polar chemicals. This study seeks to make a broad polarity range analytically accessible by means of serially coupling reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) to high-resolution mass spectrometry (HRMS). Moreover, a workflow is presented using optimized data processing of nontarget screening (NTS) data and subsequently generating candidate lists for the identification of very polar molecules via an open-access NTS platform and implemented compound database. First, key input parameters and filters of the so-called feature extraction algorithms were identified, and numerical performance indieening data is available for addressing new (very) polar substances in the aqueous environment.Honey is a complex mixture of carbohydrates, in which the monosaccharides glucose and fructose are the most abundant compounds. Currently, more than 20 oligosaccharides have been identified in different varieties of honey normally at quite low concentration. A method was developed and validated using high-performance anion-exchange chromatography coupled to a mass spectrometry detector to investigate the composition of carbohydrates in honey samples. The method was tested for linearity range, trueness, instrumental and method detection and quantification limits, repeatability, and reproducibility. It was applied to determine seven monosaccharides, eight disaccharides, four trisaccharides, and one tetrasaccharide in various honey samples. The present work describes the composition of sugars in unifloral, multifloral, and some honeydew honey, which were produced and collected by beekeepers in the Trentino Alto-Adige region. Statistical techniques have been used to establish a relationship based on levels of carbohydrates among different Italian honey. The results emphasize that mono- and oligosaccharide profiles can be useful to discriminate different honeys according to their floral characteristics and inter-annual variability.In this work, a duplex-specific nuclease (DSN)-resistant triplex-helix DNA nanoswitch was designed for assays of single-base differentiation of the let-7a family in lung cancer cells. Initially, although a 10-bp duplex stem in the nanoswitch was cleaved to pieces, a 10-bp triplex stem was resistant to DSN. Consequently, a triple-stranded DNA structure resistant to DSN was obtained. find more The pH-dependent formation of the triplex structure then produced the pH-related nanoswitch/miRNA hybrid, and the metastable nanoswitch generated an obvious signal increase at pH 6.8. Surprisingly, the pH condition at 6.8 for the best nanoswitch/miRNA hybrid is consistent with the optimal DSN catalysis, which paves the way for a first-rank DSN signal amplification (DSNSA) strategy for the single-base selective capacity of the homologous let-7a family with a limit of detection of 0.26 pM. The cyclic strategy based on the DSN-mediated triplex-helix DNA nanoswitch was verified in lung cancer cell samples and exhibited better discriminatory ability without user-unfriendly nucleotide modification or extra probe-mediated assistance, showing excellent potential for application in biomedical sensing and clinical diagnosis. Graphical abstract Based on the discovery that a triple-helix DNA nanoswitch is resistant to DSN and that the nanoswitch/miRNA hybridization was pH-related, pH at 6.8, which is suitable for the optimal nanoswitch/miRNA hybrid and DSN catalysis, reinforced the DSNSA strategy for the single-base selective capacity of the homologous let-7a family with a limit of detection of 0.26 pM.Histamine (HA) is a biogenic amine associated with allergies and food poisoning. It is an important indicator of food freshness and quality. In recent years, a series of medical negligence cases have been reported to be related to the intravenous injection of antibiotics produced via fermentation with fish peptone due to HA contamination. To detect HA efficiently, mouse monoclonal antibody was developed. An enzyme-linked immunosorbent assay (ELISA) and a chemiluminescence enzyme immunoassay (CLEIA) were developed and compared with conventional HPLC analysis. Both immunoassays showed low cross-reactivity, low 50% inhibitive concentration (IC50; 1.2 μg/mL and 1.1 μg/mL), low limits of detection (LODs, IC10; 89.0 ng/mL and 73.4 ng/mL), and appreciable recoveries in spiked foods and drugs (from 73.4 to 131.0% and from 77.0 to 119.0%, espectively), demonstrating that the developed methods are sensitive, specific, fast, and reliable for HA detection in complicated real samples. Graphical abstract.