Electrospray ion source and interface apparatus and method
AssigneesFinnigan Corporation, Analytica of Branford, Inc.
InventorsMark E. Hail, Iain C. Mylchreest
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Abstract
An electrospray interlace apparatus is disclosed. The apparatus includes an inner needle for transferring a liquid sample to an ionizing region at one end of the needle. A first outer tube surrounds and is spaced apart from the needle to form a cylindrical space through which a flowing liquid may pass. The tube has one end extending beyond the end of the needle to define a mixing volume where the sample and liquid can mix. A second outer tube surrounds the first tube to define a second cylindrical space for flowing a gas past the end of the first tube and needle to focus the electrospray. A voltage is also provided between the tips of the needle and the tubes and an adjacent surface.
Claims23
An electrospray interface apparatus for supplying and ionizing a sample bearing fluid comprising
- an ionization chamber,
- an inner hollow electrically conductive needle for conveying the sample fluid having its exit end extending into said ionization chamber,
- a first conductive tube surrounding and spaced from said needle to define a first cylindrical annular space and having the exit end extending into the ionization chamber beyond the exit end of the needle to define a mixing volume between the inner surface of said first tube and the exit end of said needle, said first cylindrical annular space serving to convey a sheath liquid to said mixing volume for mixing with said sample bearing fluid,
- means for applying a high voltage between said ionization chamber and said inner hollow needle and first tube to form an electrospray, and
- a second tube surrounding and spaced from said first tube to define therebetween a second cylindrical annular space for conveying a focusing gas to the exit end of said first tube to sheath said electrospray.
An electrospray ion source comprising:
- an ionization chamber,
- an electrospray interface apparatus for supplying sample bearing fluid to said ionization chamber and for ionizing the same to form sample ions, said electrospray interface apparatus comprising
- an inner hollow conductive needle having an exit end extending into said ionization chamber,
- a first conductive tube surrounding and spaced from said needle to form a first cylindrical annular space, the exit end of said first tube extending into said ionization chamber beyond said exit end of said needle to define a mixing volume between the inner surface of said first tube and the exit ends of said needle and first tube, said first cylindrical annular space serving to convey a sheath liquid to said mixing volume for mixing with said sample bearing fluid,
- a second tube surrounding and radially spaced from said first tube to define therewith a second cylindrical annular space,
- means for supplying a sample bearing fluid through said needle to cause fluid exiting said needle to flow into said ionization chamber,
- means for supplying a sheathing liquid through said first cylindrical annular space to flow into said mixing volume to mix with the sample bearing fluid to form a mixture,
- means for applying a voltage between the walls of said ionization chamber and said ends of said needle and first tube to form an electrospray of said mixture, and
- means for supplying a focusing gas through said second cylindrical annular space to sheath said electrospray.
The method of ionizing a sample bearing fluid in an ionization chamber by electrospray ionization which comprises the steps of
- introducing the sample bearing fluid into the ionization chamber through a hollow conductive needle whose exit end extends into said ionization chamber,
- introducing a sheathing liquid into said ionization chamber through an annular space formed between a surrounding conductive first tube and said needle, the said exit end of said tube extending beyond the exit end of said needle so that said sheathing liquid surrounds the exit end of said needle,
- mixing in a mixing volume defined between the exit ends of said needle and said first tube said sheathing liquid and the sample bearing fluid to form a mixture,
- applying a high voltage between the walls of said ionization chamber and said exit ends of said conductive needle and said first tube to form an electrospray, and
- introducing a focusing gas through the annular space defined between said first tube and a surrounding second cylindrical tube to sheath the electrospray.
A method of ionizing a sample bearing fluid in an electrospray ionization source including an ionization chamber, which comprises the steps of
- introducing said sample bearing fluid into said ionization chamber through a hollow conductive needle whose exit end extends into said ionization chamber,
- introducing a sheathing liquid into said ionization chamber through a first annular space between said needle and a surrounding first conductive tube whose exit end extends beyond the exit end of said needle so that said sheathing liquid surrounds the end of said hollow needle,
- mixing said sheathing liquid and said sample bearing fluid to form a mixture in a mixing volume, said mixing volume defined as the region between said exit of said needle and said exit end of said first tube,
- applying a voltage between the walls of said ionization chamber and said ends of said needle and first tube to form an electrospray, and
- introducing a focusing gas through a second annular space defined between said first tube and a surrounding second cylindrical tube to sheath said electrospray.
Dependencies are inferred from the claim text.