What Is the Opposite of Pandora’s Box? Direct Analysis, Ambient Ionization, and a New Generation of Atmospheric Pressure Ion Sources

Abstract

The introduction of DART and DESI sources approximately seven years ago led to the development of a new series of atmospheric pressure ion sources referred to as "ambient ionization" sources. These fall into two major categories: spray techniques like DESI or plasma techniques like DART. The selectivity of "direct ionization," meaning analysis without chromatography and with little or no sample preparation, depends on the mass spectrometer selectivity. Although high resolution and tandem mass spectrometry are valuable tools, rapid and simple sample preparation methods can improve the utility of ambient ionization methods. The concept of ambient ionization has led to the realization that there are many more ways to form ions than might be expected. An interesting example is the use of a flint-and-steel spark source to generate ions from compounds such as phenolphthalein and Gramicidin S.

Source identification of western Oregon Douglas‐fir wood cores using mass spectrometry and random forest classification

“…DART-TOFMS provides an instantaneous small molecule profile for solid samples in an open-air environment, removing the labor-intensive requirement of material preparation in chemical solvent and the potential for sample preparation biases (Cody et al, 2005; Cody, 2013). Differentiation provided by DART-TOFMS metabolite profiles has been used to discriminate wood from many closely related tree species (Cody et al, 2012; Lancaster and Espinoza, 2012a, 2012b; Espinoza et al, 2014, 2015).…”

Metabolic chemotypes of CITES protected Dalbergia timbers from Africa, Madagascar, and Asia

“…[12] A new advance in wood metabolic profiling is the use of an open-air atmospheric ionization tool called Direct Analysis in Real Time (DART) Time-Of-Flight Mass Spectrometry (TOFMS). A detailed description of the scientific principles of DART TOFMS has been given by Cody et al [13][14][15] DART TOFMS is particularly useful for analyzing solid materials; a thin wood specimen can be analyzed directly and the resulting spectrum shows all the phytochemicals extracted from the sample. DART TOFMS metabolic profiles, previously used to classify two species of American oak (Quercus spp.)…”

High-Mass Capabilities of Positive-Ion and Negative-Ion Direct Analysis in Real Time Mass Spectrometry

“…[2][3][4] DART is generally employed for analytes having molecular weights up to about 1000 Da, and thus it presents an efficient tool for analysis of a plethora of types of samples. [5][6][7][8][9] Provided thermal decomposition is not an issue, compounds of higher molecular weight can also be analysed by DART-MS, for example polydimethylsiloxanes, either as silicone oil, silicone grease or silicone rubber. [10][11][12] Positive-ion DART spectra of this compound class for the first time exhibited signals due to organic ions beyond m/z 3000.…”