Methods and apparatus for the ion mobility based separation and collection of molecules
This invention describes an apparatus and method with a combined primary electrospray and secondary electrospray ionization source used to enhance ionization efficiency. The solid phase as well as liquid phase sampling, ionization, and detection is described.
1. An apparatus for the ionization of a sample comprising:
(a) at least one primary electrospray ionization source that substantially ionizes at least one portion of the sample into gas phase ions;
(b) at least one secondary electrospray ionization source that is spatially separated from the primary electrospray ionization source, and which ionizes an un-ionized portion of the same sample into gas phase ions;
(c) a ionization chamber containing an independent electric field having a first direction along a longitudinal axis of the ionization chamber that guides charged particles in the ionization chamber along the axis
(d) a gas flow that is confined by the ionization chamber transporting the portion of the sample that is not ionized by the primary electrospray ionization source along a second direction to separate that portion from the ionized portion, where the angle between the first and second directions is substantially greater than zero; and
(e) at least one analyzer in fluid communication with the ionization chamber for the analysis of all ionized portions of the sample.
2. The apparatus of claim 1 , wherein the analyzer is an ion mobility separator or a mass analyzer.
3. The apparatus of claim 2 , wherein the mass analyzer is a quadrupole, an ion trap, or a time of flight mass analyzer.
4. The apparatus of claim 1 , wherein the analyzer is interfaced to the ionization chamber between substantially zero and substantially one hundred eighty degrees from the direction of the electric field.
5. The apparatus of claim 1 , wherein the secondary electrospray ionization source further comprises chemical modifiers.
6. A method for the ionization of samples comprising the steps of:
(a) introducing a sample into a ionization chamber that has an independent electric field along a first axis with a first direction, where said independent electric field is independent from that generated by the ion source;
(b) ionizing a portion of the sample by a primary electrospray ionization source;
(c) guiding the ionized portion of the sample using the independent electric field along the first direction;
(d) carrying the un-ionized portion of the same sample using a gas flow along a second axis with a second direction; where the angle between the first and second axis is substantially greater than zero;
(e) ionizing a portion of the un-ionized sample by a secondary electrospray ionization source that is spatially separated from the primary electrospray ionization source; and
(f) extracting the ionized sample from the ionization chamber into an analyzer for the analysis of all ionized portions of the sample.
7. The method of claim 6 , wherein the step of ionizing further comprises introducing a chemical modifiers into the ionization source.
8. The method of claim 6 , wherein the step of introducing the sample comprises a continuous or pulsed sample flow.
9. The method of claim 6 , wherein the step of ionizing the un-ionized portion of the sample comprises bringing charged particles generated by the secondary electrospray ionization source into the ionization chamber continuously or as pulses.
10. The method of claim 6 , wherein the steps of (c) (d) and (e) are repeated.