Liquid Sampling-Atmospheric Pressure Glow Discharge (LS-APGD) Ionization Source for Elemental Analysis
EMSL Project ID
44090
Abstract
The development of a novel low power, low flow 'elemental' ionization source for applications in the areas of metallomics and transportable mass spectrometry is proposed. The liquid sampling-atmospheric pressure glow discharge (LS-APGD) has been shown to be an effective excitation source for optical (atomic) emission spectroscopy, also exhibiting appreciable photon emission from ionized metal atoms. The luminescent microplasma is struck between the surface of the analyte containing solution flowing (<0.1 mL/min) from a 100 micrometer inner diameter fused silica capillary and a 2 mm diameter metallic counter electrode. The practical volume of the plasma is ~1 mm3. The operating parameters of the discharge are 10-50 mA and 200-500 V dc (i.e., <25 W). These values are in stark contrast to inductively-coupled plasma (ICP) sources commonly used in elemental mass spectrometry. In fact, the size and power requirements are more on scale with electrospray ionization (ESI) sources used in proteomics; thus the source is proposed as an elemental complement for those instruments. These characteristics also bode well for applications as elemental ionization sources for transportable mass spectrometry where size, power, and operation simplicity are at a premium. Studies are proposed to couple the LS-APGD to a ThermoScientific Exactive OrbitrapTM instrument within the Biological Separations and Mass Spectrometry Group at EMSL, under the direction of Dr. David Koppenaal. The implementation of the microplasma on the Orbitrap will proceed by directly replacing the existing ESI source on that instrument. It is not expected that the temperature or gas and liquid loads of the plasma will be a challenge to the current ion sampling interface. Successful implementation in this manner would yield a valuable complementary set of experimental capabilities that does not exist with current proteomics instruments. By the same token, the ultrahigh mass resolving powers of the Orbitrap would provide unparalleled performance in the area of elemental mass spectrometry. Finally, the MS/MS capabilities of that mass analyzer provide the greatest experimental versatility as the collisional dissociation of metal oxides, hydroxides, and hydrates could be performed as needed. It is believed that the LS-APGD represents the first viable 'miniaturized' alternative to the venerable ICP-MS, and thus would have great potential across a broad range of EMSL programs.
Project Details
Project type
Exploratory Research
Start Date
2011-05-19
End Date
2012-05-20
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Carado AJ, CD Quarles, AM Duffin, CJ Barinaga, R Russo, RK Marcus, GC Eiden, and DW Koppenaal. 2012. "Femtosecond Laser Ablation Particle Introduction to a Liquid Sampling-Atmospheric Pressure Glow Discharge Ionization Source." Journal of Analytical Atomic Spectrometry 27(3):385-389. doi:10.1039/C2JA10331A