Reduction of matrix interference for MALDI mass spectrometry analysis

• US 6,995,363 B2
• Filed: 08/09/2004
• Issued: 02/07/2006
• Est. Priority Date: 08/21/2003
• Status: Active Grant

• Current Assignee: MDS Incorporated (Molecular Devices)
• Original Assignee: MDS Incorporated (Molecular Devices), Applera Corporation (Thermo Fisher Scientific Incorporated)
• Inventors: Tomlinson, Andrew J., Donegan, Michael P., Nair, Perumanath H., Juhasz, Peter
• Primary Examiner(s): Lee, John R.
• Assistant Examiner(s): Souw, Bernard E.
• Application Number:
  US10/914,395
• Publication Number:
  US 20050040328A1
• Time in Patent Office: 547 Days
• Field of Search: 250/281, 250/282, 250/287, 250/288, 250/292, 250/294, 250/299, 250/300, 428/411.1, 428/414, 428/416, 428/418, 428/420, 428428-430, 428432-435, 428438-442, 428444-450, 428/457, 428/461, 428/475.8, 4284761- 6
• US Class Current: 250/288
• CPC Class Codes: H01J 49/0418 for laser desorption, e.g. matrix-assisted laser desorption/ionisation [MALDI] plates or surface enhanced laser desorption/ionisation [SELDI] plates
• CPC Class Codes: Y10T 428/31522 Next to metal
• CPC Class Codes: Y10T 428/31529 Next to metal
• CPC Class Codes: Y10T 428/31536 Including interfacial reaction product of adjacent layers
• CPC Class Codes: Y10T 428/31612 As silicone, silane or siloxane
• CPC Class Codes: Y10T 428/31623 Next to polyamide or polyimide
• CPC Class Codes: Y10T 428/31634 Next to cellulosic
• CPC Class Codes: Y10T 428/31649 Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31659 With cellulosic layer
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane

Abstract

A MALDI plate suitable for MS or MS-MS analysis provided with a composite coating that comprises a hydrophobic coating and a thin layer coating of a mixture of a MALDI matrix material and an intercalating agent such as a polymer is disclosed. A MALDI plate produced in accordance with the present teachings is useful for suppression of matrix ions in the low mass region (<1,000 daltons) of a MALDI-MS spectrum.

Claims

1. A sample plate for MALDI analysis comprising:

an electrically conductive substrate having a first surface, at least a portion of the first surface coated with a composite coating that comprises a hydrophobic coating and a coating of a thin film mixture of a matrix and an intercalating polymer.

2. The sample plate of claim 1 wherein the substrate is made of stainless steel.

3. The sample plate of claim 1 wherein the matrix is α

cyano-4-hydroxycinnamic acid.

4. The sample plate of claim 1 wherein the intercalating polymer is nitrocellulose.

5. The sample plate of claim 1 wherein upon ionization by laser desorption matrix ions below a mass to charge ratio of 1,000 daltons are suppressed.

6. The sample plate of claim 1 wherein the hydrophobic coating comprises an integral coating of any one of a paraffin composition, lipid, fatty acid, ester, silicon oil or wax or combinations thereof, or a polish that comprises mixtures of the foregoing that are designed to clean and protect metal surfaces.

7. The process for making a sample plate for MALDI MS or MS-MS analysis comprising:

forming a hydrophobic coating on a first surface of an electrically conductive substrate; and

forming a second coating on the first surface and the hydrophobic coating with a mixture in solution containing a matrix and an intercalating polymer to form a composite coating on the substrate.

8. The process of claim 7 where the matrix and the intercalating polymer mixture is a mixture of α

cyano-4-hydroxycinnamic acid and nitrocellulose, both components of the mixture at a concentration of between about 1 and 2 mg/mL.

9. The process of claim 8 where the matrix and the intercalating polymer mixture is a mixture of α

cyano-4-hydroxycinnamic acid and nitrocellulose in acetone.

10. The process of claim 7 wherein the hydrophobic coating comprises an integral coating of any one of a paraffin composition, lipid, fatty acid, ester, silicon oil or wax or combinations thereof, or a polish that comprises mixtures of the foregoing that are designed to clean and protect metal surfaces.

11. The process of claim 7 wherein the electrically conductive substrate is stainless steel.

12. The process of claim 7 wherein upon ionization by laser desorption matrix ions below a mass to charge ratio of 1,000 daltons are suppressed.