Means of introducing an analyte into liquid sampling atmospheric pressure glow discharge
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).
1. A liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device comprising:
an electrolyte solution source;
a first hollow tube extending from the electrolyte solution source to a first discharge end of the first hollow tube, the first hollow tube comprising an inside diameter of from about 0.1 millimeter to about 2 millimeters, the first hollow tube comprising a conductive element, the first hollow tube being in fluid communication with the electrolyte solution source and being configured to carry a flow of a liquid electrolyte solution within the first hollow tube and deliver the electrolyte solution out of the first discharge end;
an analyte source;
a second hollow tube extending from the analyte source to a second discharge end of the second hollow tube, the second hollow tube comprising an inside diameter of from about 0.1 millimeter to about 2 millimeters, the second hollow tube being in fluid communication with the analyte source and being configured to carry a flow of an aerosol including an analyte within the second hollow tube and deliver the aerosol out of the second discharge end, the first and second hollow tubes being located with respect to one another such that a flow that exits the first discharge end of the first hollow tube intersects with a flow that exits the second discharge end of the second hollow tube;
a counter electrode disposed at a distance of from about 0.1 millimeter to about 5 millimeters from the first discharge end of the first hollow tube, a terminal portion of the second hollow tube comprising the counter electrode;
a power source in electrical communication with the conductive element of the first hollow tube and with the counter electrode such that the conductive element of the first hollow tube and the counter electrode are in electrical communication with one another via the power source, the power source being configured to establish a voltage difference between the conductive element and the counter electrode across the distance; and
a glow discharge space within the distance.
2. The LS-APGD device of claim 1 , wherein one or both of the first discharge end of the first hollow tube and the second discharge end of the second hollow tube is selectively moveable.
3. The LS-APGD device of claim 1 , wherein the power source is a direct current source, a radio frequency power source, or a microwave frequency power source.
4. The LS-APGD device of claim 1 , wherein the first discharge end of the first hollow tube is formed of an electrically conductive material that forms the conductive element.
5. The LS-APGD device of claim 1 , wherein the first discharge end of the first hollow tube is formed of a non-conductive material, the conductive element of the first hollow tube being upstream of the first discharge end of the first hollow tube.
6. The LS-APGD device of claim 1 , wherein the power supply Is configured for placing a voltage difference between the conductive element and the counter electrode of from about 200 volts to about 1,000 volts direct current.
7. The LS-APGD device of claim 1 , further comprising a conduit surrounding the first discharge end of the first hollow tube.
8. The LS-APGD device of claim 1 , wherein a longitudinal axis of the first hollow tube and a longitudinal axis of the second hollow tube are aligned at about 180° with one another.
9. The LS-APGD device of claim 1 , wherein a longitudinal axis of the first hollow tube and a longitudinal axis of the second hollow tube define an angle of about 90° or greater between one another.
10. The LS-APGD device of claim 1 , wherein a longitudinal axis of the first hollow tube and a longitudinal axis of the second hollow tube define an angle of less than 90° between one another.
11. The LS-APGD device of claim 1 , wherein the analyte source comprises a laser ablation device.
12. The LS-APGD device of claim 11 , further comprising an analysis instrument in fluid or optical communication with the glow discharge space.
13. The LS-APGD device of claim 12 , wherein the analysis instrument is a mass spectrometer.
14. The LS-APGD device of claim 12 , wherein the analysis instrument is a monochromator.
15. The LS-APGD device of claim 12 , wherein the analysis instrument is a polychromator.
16. The LS-APGD device of claim 11 , wherein the laser ablation device comprises a femtosecond pulsed laser.
17. The LS-APGD device of claim 11 , wherein the laser ablation device comprises a nanosecond pulsed laser.
18. The LS-APGD device of claim 11 , wherein the laser ablation device comprises a yttrium aluminum garnet based laser.