Micro-plasma: a novel ionisation source for ion mobility spectrometry.
Ion mobility spectrometry is an analytical method for identification and quantification of gas-phase analytes in the ppb(v)-ppt(v) range. Traditional ionisation methods suffer from low sensitivity (UV light), lack of long-term stability (partial discharge), or legal restrictions when radioactive sources are used. A miniaturised helium plasma was applied as ionisation source in an ion mobility spectrometer (IMS). Experiments were carried out to compare plasma IMS with beta-radiation IMS. It could be demonstrated that the plasma IMS is characterised by higher sensitivity and selectivity than beta-radiation ionisation. Plasma IMS is approximately 100 times more sensitive than the beta-radiation IMS. Furthermore, variable sensitivity can be achieved by variation of the helium flow and the electric field of the plasma, and variable selectivity can be achieved by changing the electric field of the IMS. The experimental arrangement, optimisation of relevant conditions, and a typical application are presented in detail.
Vautz
Wolfgang
W
ISAS - Institute for Analytical Sciences, Bunsen-Kirchhoff-Strasse 11, 44139, Dortmund, Germany. vautz@isas.de
Michels
Antje
A
Franzke
Joachim
J