Generation of standard gas mixtures of halogenated, aliphatic, and aromatic compounds and prediction of the individual output rates based on molecular formula and boiling point

Abstract

In this work, we describe a simple diffusion capillary device for the generation of various organic test gases. Using a set of basic equations the output rate of the test gas devices can easily be predicted only based on the molecular formula and the boiling point of the compounds of interest. Since these parameters are easily accessible for a large number of potential analytes, even for those compounds which are typically not listed in physico-chemical handbooks or internet databases, the adjustment of the test gas source to the concentration range required for the individual analytical application is straightforward. The agreement of the predicted and measured values is shown to be valid for different groups of chemicals, such as halocarbons, alkanes, alkenes, and aromatic compounds and for different dimensions of the diffusion capillaries. The limits of the predictability of the output rates are explored and observed to result in an underprediction of the output rates when very thin capillaries are used. It is demonstrated that pressure variations are responsible for the observed deviation of the output rates. To overcome the influence of pressure variations and at the same time to establish a suitable test gas source for highly volatile compounds, also the usability of permeation sources is explored, for example for the generation of molecular bromine test gases.

Critical assessment of ionization patterns and applications of ambient desorption/ionization mass spectrometry using FAPA–MS

“…[16,17] Briefly, secondary OA particles were generated by limonene oxidation under dark and dry conditions (relative humidity (RH) < 30%) using a 100 l continuous-flow reaction vessel. Gaseous limonene was introduced into the chamber using a thermally controlled diffusion source, [18] leading to a gas-phase concentration of 290 ppb V . Ozone was generated by an ozone generator (1008-RS, Dasibi Environmental Corp., Glendale, CA, USA) and introduced into the chamber to give a concentration of roughly 1 ppm.…”

Online atmospheric pressure chemical ionization ion trap mass spectrometry (APCI-IT-MS&lt;sup&gt;n&lt;/sup&gt;) for measuring organic acids in concentrated bulk aerosol – a laboratory and field study

“…For this purpose gaseous (+)-α-pinene (Sigma-Aldrich, ≥ 99 %), generated in a thermally controlled diffusion source (Thorenz et al, 2012) was mixed with ozone (1 ppm) in the reaction chamber to produce organic aerosol particles. Ozone was generated with an ozone generator (1008-RS, Dasibi Environmental Corp., Glendale, CA, USA) and directly introduced into the reaction chamber.…”

Emission of iodine-containing volatiles by selected microalgae species

“…Therefore, we conclude that the lower iodocarbon emissions of the plankton concentrate compared to the diatom cultures is partly due to lower biomass density. The lower iodocarbon emission rates in the natural plankton concentrate could also be related to iodine uptake of naturally occurring microalgae (van Bergeijk et al, 2013). The emission flux summed for the three iodocarbons in the four samples' background, plankton concentrate, P. glacialis and M. helysia, was in the range 0.21-1.02, 0.14-0.58, 0.50-1.35 and 0.57-1,53 pmol min −1 m −2 , respectively.…”

“…Another possible reason for the low iodide concentration in the plankton concentrate could be iodine uptake by microalgae present in the natural plankton sample (van Bergeijk et al, 2013).…”