Atmospheric pressure chemical ionisation mass spectrometry for the routine analysis of low molecular weight analytes

Abstract

The routine analysis of low molecular weight analytes by mass spectrometry is often complicated by the lability of the analyte’s functional groups and/or the lack of moieties that can be easily charged. If a molecule is too labile this precludes analysis by techniques such as electron ionisation or chemical ionisation as the analyte will undergo thermal decomposition prior to ionisation as well as spontaneous fragmentation during the ionisation process. If the analyte has a low propensity to form ions in electrospray ionisation (i.e., lacks acidic or basic sites) then often no analyte related ions are observed. In this paper, the robustness and versatility of the established method of atmospheric pressure chemical ionisation is demonstrated for the analysis of low molecular weight analytes. The utility of the technique is demonstrated through the analysis of 30 reference standards of varying functionality, and further by the analysis of 75 synthetic samples which were problematic when analysed by electron or electrospray ionisation. The resulting spectra are dominated by intact molecular species ([M+H]+ and M+ in positive ion mode and [M − H]− and [M + Cl]− in negative ion mode) along with logical neutral losses reminiscent of what you might expect from the analyte’s structure (losses of H2O from alcohols or CO from aldehydes etc). This paper presents atmospheric pressure chemical ionisation as an essential tool for broadening the chemical space of successful analyses for any routine mass spectrometry service laboratory of facility.

Desorption of positive and negative ions from activated field emitters at atmospheric pressure

“…45 Finally, carbon fiber ionization 46,47 represents a technique closer related to atmospheric pressure chemical ionization (APCI). 48,49 All of these approaches [30][31][32][33][34]40,[42][43][44][45][46][47] demonstrate that the surface of essentially any object providing one or numerous sharp tips can potentially act as a means of sample supply and electric field enhancement enabling ion desorption from a liquid film into the gas phase provided this sampling device is at high potential relative to a counter electrode. Typically, this counter electrode is provided by the sampling cone at the entrance of an API interface.…”

“… 45 Finally, carbon fiber ionization 46 , 47 represents a technique closer related to atmospheric pressure chemical ionization (APCI). 48 , 49 …”

Heterometathesis of diphosphanes (R2P–PR2) with dichalcogenides (R′E–ER′, E = O, S, Se, Te)

“…The product was isolated in 92% yield and further characterised by 1 H and 13 C{ 1 H} NMR, and mass spectrometry (see ESI† for the data). 25 Crystals of 1 were grown from CH 2 Cl 2 / n -hexane via vapour diffusion and its X-ray crystal structure determined (see Fig. 1).…”

Don't sleep on sampling: if you don’t catch it, you can’t see it

“…API was chosen in order eliminate using a spray solvent and would be suitable to direct analysis of SERS substrates. However, API without a spray solvent does have application limitations that would point to utilizing PS-MS 13,14 . First, the analysis targets must be able to vaporize off the paper.…”