Devices and methods for MAI ionization
Mass spectrometry systems and methods including ionization devices are provided. The ionization device includes either a gas pulse valve or a piezoelectric striker. The ionization device is configured to direct force to the back of a substrate, where an analyte of interest is deposited on the front of the substrate. The impact ionizes the analyte and the ions are directed into a mass spectrometer for analysis.
1. A mass spectrometer system comprising:
a sample mount configured to hold a sample substrate, wherein the sample substrate has an opposing front side and a back side, wherein a sample is on the front side of the sample substrate;
an ionization device configured to direct a force at the back side of a sample substrate to propagate a shockwave, wherein the ionization device is at a first distance adjacent the sample mount; and
a mass spectrometer having an inlet, wherein the sample mount is positioned a second distance from the inlet.
2. The mass spectrometer system of claim 1 , wherein the ionization device comprises:
a pulsed valve having a first gas flow port, wherein the first gas flow port has a closed position and an open position, wherein the first gas flow port has an inlet and an exit, wherein the pulsed valve has a gas inlet in gaseous communication with the inlet of the first gas flow port, wherein when the first gas flow port is in the closed position, the first gas flow port is configured so that gas does not flow through the first gas flow port, wherein when the first gas flow port is in the open position, the first gas flow port is configured so that gas flows through the inlet and out of the exit of the first gas flow port; and
the gas exiting the first gas flow port impacts the sample mount having a sample positioned thereon; and
wherein ions of the sample are produced upon impact of gas on the sample mount, and the ions pass into the inlet.
3. The mass spectrometer system of claim 2 , wherein the pulsed valve is a solenoid valve having an orifice diameter of about 0.25 to about 1 mm.
4. The mass spectrometer system of claim 2 , further comprising a pulsing system that is configured to use a pulse to move the first gas flow port from the closed position to the open position, wherein the pulse has a pulse duration of about 250-100 μs.
5. The mass spectrometer system of claim 2 , further comprising a gas input system in gaseous communication with the gas inlet of the pulse valve, wherein the gas from the gas input system is discharged at a pressure of about 500 kPa to about 700 kPa.
6. The mass spectrometer system of claim 1 , wherein the mass spectrometer is selected from an ion trap mass spectrometer, a time-of-flight mass spectrometer, a quadrupole mass filter mass spectrometer, an ICR mass spectrometer, a sector mass spectrometer, and a quadrupole time-of-flight hybrid mass spectrometer.
7. The mass spectrometer system of claim 1 , wherein the ionization device comprises:
a piezoelectric cantilever having a precision striker positioned to impact a rear side of a metal foil attached to the sample mount; and
wherein ions of a sample are produced upon impact of the striker on the metal foil, and the ions pass into the inlet.
8. The mass spectrometer system of claim 7 , wherein the piezoelectric cantilever is a bimorph piezoelectric cantilever with a frequency of about 300 Hz.
9. The mass spectrometer system of claim 7 , wherein the sample mount is placed so that the rear side of the metal foil is about 250 μm from the a tip of the precision striker when the piezoelectric cantilever is in an unactuated position, and front side of the metal foil is about 4 mm from the inlet of the mass spectrometer.
10. A method for mass spectrometer ionization comprising:
directing a force at a back side of a sample substrate, wherein a sample is disposed on a front side of the sample substrate opposite of where the force is directed, wherein the sample includes at least one analyte; and
forming ions of one or more of the analytes upon impact of the force on the back side of the sample substrate.
11. The method of claim 10 , wherein the force is selected from piezoelectric force or a pulsed gas.
12. The method of claim 11 , wherein the force is a piezoelectric force generated by a piezoelectric cantilever, and the sample substrate is disposed on a sample mount adjacent the piezo electric cantilever so that a strike of the piezoelectric cantilever impacts the back side of the sample substrate.
13. The method of claim 12 , wherein the piezoelectric cantilever has a frequency of about 200 Hz.
14. The method of claim 10 , wherein directing includes:
opening a first gas flow port of a pulsed valve so that gas flows through the first gas flow port toward the back side of the sample substrate.
15. The method of claim 14 , wherein the force is a pulsed gas, and the sample substrate is disposed on a sample mount adjacent the exit of the first gas flow port so that the gas exiting the first gas flow port impacts the back side of the sample substrate.
16. The method of claim 14 , wherein the pulsed valve is a solenoid valve having an orifice diameter of about 0.25 to about 1 mm, a pulse duration of about 250-100 μs, and wherein the pulse of gas is discharged at a pressure of about 500 kPa to about 700 kPa.
17. The method of claim 10 , further comprising:
sampling the ions of the one or more analytes using a mass spectrometer, wherein the ions enter the mass spectrometer, wherein the sample mount is positioned a first distance from the inlet of the mass spectrometer.
18. The method of claim 10 , wherein the mass spectrometer is selected from an ion trap mass spectrometer, a time-of-flight mass spectrometer, a quadrupole mass filter mass spectrometer, an ICR mass spectrometer, a sector mass spectrometer, and a quadrupole time-of-flight hybrid mass spectrometer.