The structure-giving role of Rb ions for water-ice nanoislands supported on Cu(111).

We characterize the effect of rubidium ions on water-ice nanoislands in terms of area, fractal dimension, and apparent height by low-temperature scanning tunneling microscopy. Water nanoislands on the pristine Cu(111) surface are compared to those at similar coverage on a Rb pre-covered Cu(111) surface to reveal the structure-giving effect of Rb. The presence of Rb induces changes in the island shape, and hence, the water network, without affecting the nanoisland volume.

Studies pertaining to the monitoring of volatile halogenated anaesthetics in breath by proton transfer reaction mass spectrometry.

Post-operative isoflurane has been observed to be present in the end-tidal breath of patients who have undergone major surgery, for several weeks after the surgical procedures. A major new non-controlled, non-randomized, and open-label approved study will recruit patients undergoing various surgeries under different inhalation anaesthetics, with two key objectives, namely (1) to record the washout characteristics following surgery, and (2) to investigate the influence of a patient's health and the duration and type of surgery on elimination. In preparation for this breath study using proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS), it is important to identify first the analytical product ions that need to be monitored and under what operating conditions.

Selective Reagent Ion Mass Spectrometric Investigations of the Nitroanilines.

This paper presents an investigation of proton and charge transfer reactions to 2-, 3- and 4-nitroanilines (CHNO) involving the reagent ions HO·(HO) (n = 0, 1 and 2) and O, respectively, as a function of reduced electric field (60-240 Td), using Selective Reagent Ion-Time-of-Flight-Mass Spectrometry (SRI-ToF-MS). To aid in the interpretation of the HO·(HO) experimental data, the proton affinities and gas-phase basicities for the three nitroaniline isomers have been determined using density functional theory. These calculations show that proton transfer from both the HO and HO·HO reagent ions to the nitroanilines will be exoergic and hence efficient, with the reactions proceeding at the collisional rate.

Compendium of the Reactions of HO With Selected Ketones of Relevance to Breath Analysis Using Proton Transfer Reaction Mass Spectrometry.

Soft chemical ionization mass spectrometric techniques, such as proton transfer reaction mass spectrometry (PTR-MS), are often used in breath analysis, being particularly powerful for real-time measurements. To ascertain the type and concentration of volatiles in exhaled breath clearly assignable product ions resulting from these volatiles need to be determined. This is difficult for compounds where isomers are common, and one important class of breath volatiles where this occurs are ketones.

Enhancement of Compound Selectivity Using a Radio Frequency Ion-Funnel Proton Transfer Reaction Mass Spectrometer: Improved Specificity for Explosive Compounds.

A key issue with any analytical system based on mass spectrometry with no initial separation of compounds is to have a high level of confidence in chemical assignment. This is particularly true for areas of security, such as airports, and recent terrorist attacks have highlighted the need for reliable analytical instrumentation. Proton transfer reaction mass spectrometry is a useful technology for these purposes because the chances of false positives are small owing to the use of a mass spectrometric analysis.