High intensity ion source apparatus for mass spectrometry

An apparatus for providing gas phase ions in a relatively low pressure region from a liquid including a matrix material, the apparatus comprising:

• (a) a capillary tube, said capillary tube having an input receiving the liquid, a longitudinal bore, and an outlet for discharging said liquid at a preset flow rate into a first region at a relatively high pressure;
• (b) pulsing means coupled to the capillary tube for providing a series of pressure pulses to the liquid within the capillary tube to cause said capillary tube to expel a series of liquid stream droplets;
• (c) a first interface element with an aperture therein and separating said first region from a second region at a relatively low pressure;
• (d) desolvation means for desolvating the liquid stream droplets into gas phase ions in the second region,
• wherein the outlet of the capillary tube is aligned with the aperture of the first interface element and is positioned directly in front of, and in close proximity to, the aperture of the first interface element, whereby, in use, when said pulsing means provides sufficient pulsing action to the capillary tube to cause the liquid stream flowing through the outlet of the capillary tube at the preset flow rate to become pulsed liquid stream that originates at the outlet of the capillary tube and flows through the aperture of the first interface element into the second region, said desolvation means interacts with said matrix material to create reagent ions and to substantially desolvate said pulsed liquid stream into gas phase ions in the second region, and wherein the spacing between the outlet of the capillary tube and the aperture of the first interface element is such that the liquid stream issuing from the outlet of the capillary tube is substantially drawn through the aperture of the first interface element into the second region before dispersing into charged droplets in the second region.

A method of forming gas phase ions in a relatively low pressure region from a liquid, the method comprising the steps of:

• (a) directing the liquid through a capillary tube having an outlet to provide a liquid stream at a preset flow rate into a first region at a relatively high pressure;
• (b) providing an electrode downstream from the outlet;
• (c) providing a first interface element including an aperture and separating the first region from a second region at a relatively low pressure;
• (d) positioning the capillary tube such that the outlet of the capillary tube is aligned with the aperture of the first interface element and is positioned in front of, and inclose proximity to, the aperture of the first interface element;
• (e) applying an electric potential between the liquid within said capillary tube and the electrode to form an electric field sufficient to cause said liquid stream to form a liquid stream in the form of a Taylor cone having a jet region;
• and
• (f) locating the cutlet of the capillary tube at a such a close distance from the aperture such that said jet region of the Taylor cone is positioned within the aperture of the first interface element such that the liquid stream disperses into charged droplets substantially in the second region.

A method of forming gas phase ions in a relatively low pressure region from a liquid containing a matrix material, the method comprising the steps of:

• (a) directing the liquid through a capillary tube having an outlet to provide a liquid stream at a preset flow rate into a first region at a relatively high pressure;
• (b) providing a first interface element including an aperture and separating the first region from a second region at a relatively low pressure;
• (c) positioning the capillary tube such that the outlet of the capillary tube is aligned with the aperture of the first interface element and is positioned in front of, and in close proximity to, the aperture of the first interface element;
• (d) applying pressure pulses to the capillary tube to cause said capillary tube to expel a series of liquid charge stream droplets to cause the liquid stream flowing through the outlet of the capillary tube to become a pulsed liquid stream that originates at the outlet of the capillary tube and flows through the aperture of the first interface element into the second region;
• (e) locating the outlet of the capillary tube at a such a close distance from the aperture such that the liquid charge stream issuing from the outlet of the capillary the is substantially drawn through the aperture of the first interface element into the second region before dispersing into charged droplets in the second region;
• and
• (f) desolvation said droplets into gas phase ions in the second region.