Miniaturation or downscaling of mass spectrometer is a growing field, especially in the space and military sector. Operators should be able to carry the devices around to do on-site analysis of various substances, such as toxins, pesticides or explosives. Within this project students from University Purdue took their portable gadgets to the grocery stores to proof the real life application.
Such projects are awesome - I wonder how customers reacted?
In this case two ionization methods were performed - plasma ionization and paperspray ionization. During paperspray ionization a sample is wiped with an solvent-wetted tissue, which is later cut into a small triangle in order to produce a electrospray at the tip when HV is applied to it.
The second method, called low temperature plasma ionization (LTP). The LTP probe produces long lasting meta-ions (plasma) from reagent gas (He,N2) via a low frequency AC voltage induced discharge afterglow. The afterglow is usually a sign of the presence of excited particle species. These particle ionize molecules on the sample surface, which are then desorbed by the MS. LTP ionization causes less radical formation and analyte fragmentation compared to APCI. In contrast to DART, LTP plasma is not heated up to facilitate sample desorption.
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