Means of introducing an analyte into liquid sampling atmospheric pressure glow discharge

Inventors

Marcus, R. Kenneth • Quarles, JR., Charles Derrick • Russo, Richard E. • Koppenaal, David W. • Barinaga, Charles J. • Carado, Anthony J.

Assignees

Pacific Northwest National Laboratory • Clemson University • Battelle Memorial Institute Inc • Lawrence Berkeley National Laboratory • University of California San Diego UCSD

Abstract

A liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device as well as systems that incorporate the device and methods for using the device and systems are described. The LS-APGD includes a hollow capillary for delivering an electrolyte solution to a glow discharge space. The device also includes a counter electrode in the form of a second hollow capillary that can deliver the analyte into the glow discharge space. A voltage across the electrolyte solution and the counter electrode creates the microplasma within the glow discharge space that interacts with the analyte to move it to a higher energy state (vaporization, excitation, and/or ionization of the analyte).

Core Innovation

The invention relates to a liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device and systems that incorporate the device. The LS-APGD device includes a first hollow capillary delivering an electrolyte solution to a glow discharge space and a second hollow capillary serving as a counter electrode that delivers an aerosol containing the analyte into the glow discharge space. A voltage applied across the electrolyte solution and the counter electrode establishes a microplasma within the glow discharge space that interacts with the analyte to raise it to a higher energy state, i.e., vaporizing, exciting, and/or ionizing the analyte.

The background problem addressed is the need for smaller, low power, compact sources for elemental analysis that match the small size of samples produced by laser ablation, contrasting with the large, high power inductively coupled plasma (ICP) sources. Conventional ICP sources are not cost efficient or physically sized appropriately for the nano- or micro-scale samples generated by laser ablation, and they consume large amounts of gas and sample solution. There is a recognized need for secondary sources capable of vaporization, excitation, and ionization of analytes suitable for small sample sizes with lower operational costs, smaller footprints, and lower energy consumption.

This invention innovatively solves these problems by introducing an LS-APGD device with a hollow capillary counter electrode to directly deliver an analyte-containing aerosol into a microplasma glow discharge space maintained between the first and second hollow capillaries. The device facilitates interaction of the microplasma with solid, liquid, or gaseous analytes, efficiently vaporizing and exciting or ionizing them. Such direct analyte introduction into the microplasma is particularly advantageous for analyzing small-volume samples such as those from femtosecond laser ablation and allows coupling to analysis instruments like monochromators or mass spectrometers.

Claims Coverage

The patent includes one independent claim that discloses a liquid sampling atmospheric pressure glow discharge device with distinct structural and functional features.

These features collectively define a device capable of maintaining a glow discharge at atmospheric pressure by flowing electrolyte and analyte-containing aerosols through two hollow tubes with a controlled spacing, and facilitating analysis of the excited or ionized analyte emitted from the glow discharge space.

Stated Advantages

Documented Applications