Effects of Different Waveforms on the Performance of Active Capillary Dielectric Barrier Discharge Ionization Mass Spectrometry.
Active capillary dielectric barrier discharge ionization (DBDI) is emerging as a compact, low-cost, and robust method to form intact ions of small molecules for detection in near real time by portable mass spectrometers. Here, we demonstrate that by using a 10 kHz, ~2.5 kVp-phigh-voltage square-wave alternating current plasma, active capillary DBDI can consume less than 1 μW of power. In contrast, the power consumed using a sine and triangle alternating current waveform is more than two orders of magnitude higher than that for the square waveform to obtain a similar voltage for plasma generation. Moreover, the plasma obtained using a square waveform can be significantly more homogenous than that obtained using sine and triangle waveforms. Protonated dimethyl methylphosphonate (DMMP) and deprotonated perfluorooctanoic acid (PFOA) can be detected at about the same or higher abundances using square-wave DBDI mass spectrometry compared with the use of sine and triangle waveforms. By use of benzylammonium thermometer ions, the extent of internal energy deposition using square, sine, or triangle waveform excited plasmas are essentially the same at the optimum voltages for ion detection. Using an H-bridge circuit driving a transformer optimized to reduce losses, square-wave active capillary DBDI can be continuously powered for ~50 h by common 9 V-battery (PP3). Graphical Abstract ᅟ.
School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia.
Morphy C
MC
Dumlao
School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia.
Dan
D
Xiao
School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia.
Daming
D
Zhang
School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia.
John
J
Fletcher
School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia. w.donald@unsw.edu.au.
William A
WA
Donald
Chemical warfare agents; Dielectric barrier discharge ionization; Dimethyl methyl phosphonate; Low temperature plasma ionization; Nerve agents; Perfluorooctanoic acid; Persistent organic pollutants; Portable mass spectrometry; Thermometer ions