Development of sequential online extraction electrospray ionization mass spectrometry for accurate authentication of highly-similar Atractylodis Macrocephalae.

The accurate and rapid authentication techniques and strategies for highly-similar foods are still lacking. Herein, a novel sequential online extraction electrospray ionization mass spectrometry (S-oEESI-MS) was developed to achieve spatio-temporally resolved ionization and comprehensive characterization of complex foods with multi-components (high, medium, and low polarity substances). Meanwhile, a characteristic marker screening method and an integrated research strategy based on MS fingerprinting, characteristic marker and chemometrics modeling were established, which are especially suitable for the accurate and rapid authentication of highly-similar foods that are difficult to be authenticated by traditional techniques (e.

Combinatorial optimization and spatial remodeling of CYPs to control product profile.

Activating inert substrates is a challenge in nature and synthetic chemistry, but essential for creating functionally active molecules. In this work, we used a combinatorial optimization approach to assemble cytochrome P450 monooxygenases (CYPs) and reductases (CPRs) to achieve a target product profile. By creating 110 CYP-CPR pairs and iteratively screening different pairing libraries, we demonstrated a framework for establishing a CYP network that catalyzes six oxidation reactions at three different positions of a chemical scaffold.

Polarity-Specific Profiling of Metabolites in Single Cells by Probe Electrophoresis Mass Spectrometry.

Sensitive analysis of metabolites in a single cell is of fundamental significance for the better understanding of biological variability, differential susceptibility in disease therapy, and cell-to-cell heterogeneity as well. Herein, polarity-specific profiling of metabolites in a single cell was implemented by probe electrophoresis mass spectrometry (PEMS), which combined electrophoresis sampling of metabolites from a single cell and nanoelectrospray ionization-mass spectrometry (nanoESI-MS) analysis of the sampled metabolites. Enhanced extraction of either negatively or positively charged metabolites from a single cell was achieved by applying a DC voltage offset of +2.

Enrichment of Surface-Active Compounds in Bursting Bubble Aerosols.

The pronounced enrichment of surface-active compounds in the aerosols produced by bubble bursting plays a central role in the chemical transfer from the ocean into the atmosphere and has an important impact on the global Earth's climate. However, the mechanism of chemical enrichment in bursting bubble aerosols remains poorly understood and controversial due to the high complexity and diversity of experimental behaviors. Contrary to the common belief, here we show that the major share of surfactants in the jet droplets produced by individually bursting bubbles at a calm solution surface is released directly from the bubble surface rather than from the solution surface or subsurface microlayer.

Chemical Profiling of Bulk Alloys Using Micro-Electrochemical Probe Mass Spectrometry.

Micro-electrochemical probe mass spectrometry (μECP-MS) is demonstrated as a method for the direct profiling of chemical composition of bulk alloy samples without tedious sample pretreatment. The spatial distribution of Zn and Cu components of a Cu/Zn alloy sample was successively identified by scanning the electrolysis potential from -0.6 V to 0.

Rapid detection of metal impurities on the surfaces of intact objects with irregular shapes using electrochemical mass spectrometry.

New approaches are demanded in daily life and industry for the rapid inspection of chemical impurities on various objects, particularly those with irregular shapes. Herein, an analytical strategy combining electrochemistry (EC) and mass spectrometry (MS) has been developed for the direct inspection of metal impurities on various objects which are commonly used in daily life and industry. An intact object (e.

Deciphering the chemical origin of the semen-like floral scents in three angiosperm plants.

The chemical origin and biological role of distinct semen-like odor occasionally found in some flowers are very curious but remain scarcely studied. Here, we used direct ambient corona discharge ionization mass spectrometry (MS) to study the volatile chemical composition behind the semen-like odor emitted by the fresh flowers of Photinia serrulata, Castanopsis sclerophylla and Stemona japonica without any chemical pretreatment. Chemical identification was performed using high-resolution MS analysis in combination with tandem MS analysis and whenever possible was confirmed by the analysis of standard reference compounds.

On the chemistry of 1-pyrroline in solution and in the gas phase.

1-Pyrroline has a highly characteristic odor, which is employed by living organisms for chemical signaling and other purposes, but the mechanism whereby this odor is formed remains poorly understood. Here we used a combination of ambient mass spectrometry (AMS) and nuclear magnetic resonance (NMR) spectroscopy to experimentally address the mechanistic aspects of 1-pyrroline volatility and other controversies regarding the chemistry of this compound. Our results indicate that in solution the volatility of the monomer species is significantly higher than that of the trimer species, and 1-pyrroline is evaporated mainly in its monomer state.