Mass spectrometers are sensitive tools used to identify and quantify both small and large analytes using the mass-to-charge ratios ( m/ z) of ions generated by electrospray ionization (ESI) or other methods. Ionization typically generates protonated or deprotonated forms of the analytes or adducts with adventitious metal ions derived from the spray solvent. The formation of a variety of ionized forms of the analyte as well as the presence of cluster ions complicates the data and can have deleterious effects on the performance of the mass spectrometer, especially under high salt or buffer conditions. To address this, a method involving a dual-electrode nano-electrospray source has been implemented to rapidly and temporarily desalt the spray solution of interfering cationic and anionic species using electrophoretic transport from the spray tip. Peptides, proteins, and pharmaceutical drugs all showed improved results after the desalting process as measured by the quality of the mass spectra and the limits of detection achieved. Importantly ordinary phosphate buffers could be used to record protein mass spectra by nano-ESI.

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The naturally lackadaisical kinetics of oxygen reduction reaction (ORR) in the cathode is one of the important factors that restrict the development of air-cathode microbial fuel cells (MFCs). In this work, the iron-nitrogen-carbon hierarchically nanostructured materials had been successfully fabricated by pyrolyzing glucose, iron chloride, and dicyandiamide with the aim of solving the issue. The obtained catalyst with an ultrathin nanostructure demonstrated an idiosyncratic electrocatalytic activity caused by the high content introduction of nitrogen and iron atoms, large surface area, which will offer sufficient active sites for improving the charge/mass transfer and reducing the diffusion resistance. Furthermore, with the increase of N dopant in the catalyst, better ORR catalytic activity could be achieved. Illustrating the N doping was beneficial to the ORR process. The high content of N, BET surface area caused by the N increasing could be responsible for the superior performance according to results of X-Ray photoelectron spectroscopy (XPS), Raman and Brunner-Emmet-Teller (BET) analysis. The ORR on the Fe-N 3 /C material follows 4e − pathway, and MFCs equipped with Fe-N 3 /C catalyst achieved a maximum power density (MPD) of 912 mW/m 2 , which was 1.1 times of the MPD generated by the commercial Pt/C (830 mW/m 2 ). This research not only provided a feasible way for the fabrication of Pt-free catalyst towards oxygen reduction but also proposed potential cathode catalysts for the development of MFCs.

A rapid method is described for quantification of six illegal colorants in beverages, i.e., soft beverages, energy beverages, alcoholic beverages, teas, and fruit juices.