The application of this new methodology to the analysis of a DOM is illustrated by the isolation of the molecular ion [C18H18O10-H]- in the presence of other isobars at nominal mass 393. Five IMS bands were assigned to the heterogeneous ion mobility profile of [C18H18O10-H]-, and candidate structures from the PubChem database were screened based on their ion mobility and the MS/MS matching score.  https://www.selleckchem.com/products/ly2606368.html  This approach overcomes traditional challenges associated with the similarity of fragmentation patterns of DOM samples (e.g., common neutral losses of H2O, CO2, and CH2-H2O) by narrowing down the isomeric candidate structures using the mobility domain.Glycine (Gly), an achiral amino acid, has never been reported for enantioselective recognition owing to the absence of chiral sites. Herein, a facile strategy of chirality transfer is proposed to endow Gly with chirality. Optically active CuO, L-CuO, is first prepared, which can be used for the decoration of Gly through the formation of the Cu(Gly)2 complex. Successful chirality transfer from L-CuO to Gly is confirmed by circular dichroism (CD) spectra. The formation of the Cu(Gly)2 complex is further confirmed by Fourier transform infrared spectra and X-ray photoelectron spectroscopy. Next, the resultant L-CuO-Gly is used for chiral analysis of the isomers of tryptophan (Trp). Because of the higher affinity of L-CuO-Gly toward L-Trp than its isomer, the Trp isomers exhibit significant differences in their oxidation peak currents at the L-CuO-Gly-modified glassy carbon electrode (GCE) (IL-Trp/ID-Trp = 5.24). Finally, the practicability of the developed L-CuO-Gly/GCE is assessed, and the results indicate that it could be a reliable chiral sensor for the quantitative analysis of Trp isomers in nonracemic mixtures.Single-cell analysis contributes to the understanding of cellular heterogeneity and behaviors. Nitric oxide (NO) is an important intracellular and intercellular signaling molecule, and the functions of NO are closely related to the balance between intra- and extracellular NO levels. In this manuscript, a convenient and reliable method based on a dual-labeling strategy using capillary electrophoresis (CE) separation with laser-induced fluorescence (LIF) detection has been presented for quantifying intra- and extracellular NO simultaneously in single cells. Followed by single-cell injection, a plug of HEPES buffer containing 1,3,5,7-tetramethyl-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacene and disodium 2,6-disulfonate-1,3-dimethyl-5-hexadecyl-8-(3,4-diaminophenyl)-4,4'-difluoro-4-bora-3a,4a-diaza-s-indacene as the labeling reagents for intra- and extracellular NO, respectively, was aspirated from the inlet of the capillary. The on-line derivatization was carried out on the tip of the capillary at room temperature for 20 min. Then, the cell was lysed and NO derivatives were well separated within 14 min, producing mass detection limits (S/N = 3) of 2.4 and 8.1 amol for intra- and extracellular NO, respectively. The proposed method was validated by simultaneous analysis of intra- and extracellular NO in single macrophage cells. The dual labeling-based CE-LIF method holds great promise for research on the functions of NO as well as other bioactive molecules at the single-cell level.This work reports the development of an oil-immersed scanning micropipette contact method, a variant of the scanning micropipette contact method, where a thin layer of oil wets the investigated substrate. The oil-immersed scanning micropipette contact method significantly increases the droplet stability, allowing for prolonged mapping and the use of highly evaporative saline solutions regardless of ambient humidity levels. This systematic mapping technique was used to conduct a detailed investigation of localized corrosion taking place at the surface of an AA7075-T73 aluminum alloy in a 3.5 wt % NaCl electrolyte solution, which is typically challenging in the conventional scanning micropipette contact method. Maps of corrosion potentials and corrosion currents extracted from potentiodynamic polarization curves showed good correlations with the chemical composition of surface features and known galvanic interactions at the microscale level. This demonstrates the viability of the oil-immersed scanning micropipette contact method and opens up the avenue to mechanistic corrosion investigations at the microscale level using aqueous solutions that are prone to evaporation under noncontrolled humidity levels.Photoactivation and photodissociation have long proven to be useful tools in tandem mass spectrometry, but implementation often involves cumbersome and potentially dangerous configurations. Here, we redress this problem by using a fiber-optic cable to couple an infrared (IR) laser to a mass spectrometer for robust, efficient, and safe photoactivation experiments. Transmitting 10.6 μm IR photons through a hollow-core fiber, we show that such fiber-assisted activated ion-electron transfer dissociation (AI-ETD) and IR multiphoton dissociation (IRMPD) experiments can be carried out as effectively as traditional mirror-based implementations. We report on the transmission efficiency of the hollow-core fiber for conducting photoactivation experiments and perform various intact protein and peptide analyses to illustrate the benefits of fiber-assisted AI-ETD, namely, a simplified system for irradiating the two-dimensional linear ion trap volume concurrent with ETD reactions to limit uninformative nondissociative events and thereby amplify sequence coverage. We also describe a calibration scheme for the routine analysis of IR laser alignment and power through the fiber and into the dual cell quadrupolar linear ion trap. In all, these advances allow for a more robust, straightforward, and safe instrumentation platform, permitting implementation of AI-ETD and IRMPD on commercial mass spectrometers and broadening the accessibility of these techniques.Digital PCR (dPCR) is a promising method for performing liquid biopsies that quantifies nucleic acids more sensitively than real-time PCR. However, dPCR shows large fluctuations in the fluorescence intensity of droplets or wells due to insufficient PCR amplification in the small partitions, limiting the multiplexing capability of using the fluorescence intensity. In this study, we propose a measurement method that combines dPCR with melting curve analysis for highly multiplexed genotyping. A sample was digitized into a silicon chip with up to 2 × 104 wells in which asymmetric PCR was performed to obtain more single-stranded amplicons that were complementary to molecular beacon probes. Fluorescence images were captured while controlling the temperature of the chip, and the melting curve was measured for each well. Then, genotyping was performed by using the fluorescence intensity, the dye color of the probe, and the melting temperature (Tm). Because the Tm of the PCR products is not highly dependent on the amplification efficiency of PCR, genotyping accuracy is improved by using Tm values, enabling highly multiplexed genotyping.