Multilayer flow electrospray ion source using improved sheath liquid

• US 5,122,670 A
• Filed: 05/17/1991
• Issued: 06/16/1992
• Est. Priority Date: 05/17/1991
• Status: Expired due to Fees

• Current Assignee: Finnigan Corporation (Thermo Fisher Scientific Incorporated)
• Original Assignee: Finnigan Corporation (Thermo Fisher Scientific Incorporated)
• Inventors: Hail, Mark E., Mylchreest, Iain C.
• Primary Examiner(s): Berman, Jack I.
• Assistant Examiner(s): NGUYEN, KIET TUAN
• Application Number:
  US07/702,235
• Time in Patent Office: 396 Days
• Field of Search: 250/423 R, 250/288 R, 250/288 A, 250/281, 250/282, 204/299 R
• US Class Current: 250/423.00R
• CPC Class Codes: G01N 30/38 Flow patterns
• CPC Class Codes: G01N 30/7266 by electric field, e.g. electrospray
• CPC Class Codes: G01N 30/7293 Velocity or momentum separators
• CPC Class Codes: H01J 49/165 Electrospray ionisation

Abstract

An electrospray ion source in which the liquid sample is sheathed with a sheath liquid which reduces the formation of water droplets and minimizes formation of high energy neutrals, resulting in improved signal-to-noise ratios.

Claims

1. An electrospray ion source of the type which includes an ionization chamber into which sheathed liquid sample is introduced and an adjacent low pressure region with means communicating between the ionization chamber and the lower pressure region whereby ions and gases in said ionization chamber flow into said region, the improvement comprising

using a sheath liquid which has low surface tension, is compatible with liquid samples having high water percentage, is miscible with water, methanol and acetonitrile, and has a boiling point higher than water.

2. An electrospray ion source as in claim 1 in which said sheath liquid is 2-methoxyethanol.