Increasing ionization efficiency in mass spectrometry

• US 7,276,378 B2
• Filed: 02/23/2004
• Issued: 10/02/2007
• Est. Priority Date: 05/31/2000
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Myerson, Joel
• Primary Examiner(s): KETTER, JAMES S
• Application Number:
  US10/785,621
• Publication Number:
  US 20040166586A1
• Time in Patent Office: 1,317 Days
• Field of Search: None
• US Class Current: 436/86
• CPC Class Codes: H01J 49/0431 for liquid samples interfaces to liquid chromatographs G01N30/7233
• CPC Class Codes: Y10T 436/143333 Saccharide [e.g., DNA, etc.]
• CPC Class Codes: Y10T 436/24 Nuclear magnetic resonance, electron spin resonance or other spin effects or mass spectrometry
• CPC Class Codes: Y10T 436/25 including sample preparation

Abstract

A system for the analysis of polyionic molecules by mass spectrometry is provided. The polyionic molecule is attached to a charged tag which neutralizes some of the charge on the polyionic analyte. The formed adduct with a reduced net charge is then analyzed by mass spectrometry, and the determined molecular weight of the adduct can be used to calculate the molecular weight of the analyte. Mass spectrometric analyses of polynucleotides and proteins are particularly amenable to this method.

Claims

1. A method of analyzing a polyionic molecule by mass spectrometry, the method comprising steps of:

providing a polyionic molecule;

attaching at least one non-charged tag to the polyionic molecule to produce a polyionic molecule/tag adduct;

modifying the tag to create charges on the tag, wherein the net charge on the adduct differs from that of the polyionic molecule; and

analyzing the adduct by mass spectrometry.

3. A method of claim 1 wherein the step of providing comprises incorporating a charged tag into the polyionic molecule during synthesis of the molecule.

4. A method of claim 1 wherein the step of providing comprises providing a polynucleotide.

5. A method of claim 1 wherein the step of providing comprises providing a protein.

6. A method of claim 1 wherein the step of attaching comprises attaching at least one positively charged tag.

7. A method of claim 1 wherein the step of attaching comprises attaching at least one negatively charged tag.

8. A method of claim 1 wherein the step of attaching comprises attaching at least one tag having both negatively and positively charged groups.

9. A method of claim 1 wherein the step of attaching comprises attaching a tag having at least one quaternary ammonium group.

10. A method of claim 1 wherein the step of attaching comprises attaching the tag by a covalent bond.

11. A method of claim 1 wherein the step of attaching comprises attaching more than one tag.

12. A method of claim 1 wherein the step of attaching comprises attaching the tag to anywhere on the molecule.

13. A method of claim 1 wherein the step of attaching comprises attaching the same number of tags to each molecule.

14. A method of claim 1 wherein the step of attaching comprises resulting in the net charge on the adduct being selected from the group consisting of +3, +2, +1, 0, −

1, −

2, or −

3.

15. A method of claim 1 wherein the step of attaching comprises resulting in the net charge on the adduct being a value other than +1 or −

1.

16. A method of claim 1 wherein the step of attaching comprises reducing the net charge on the adduct.

18. A method of claim 1 wherein the step of the modifying comprises steps of:

deprotecting functional groups on the tag; and

creating charges on tag after deprotection.

2. A method of analyzing a collection of polyionic molecules by mass spectrometry, the method comprising steps of:

providing a collection of polyionic molecules, wherein the molecules have different charges;

attaching at least one non-charged tag to each polyionic molecule to produce a collection of polyionic molecule/tag adducts;

modifying the tag to create charges on the tag, wherein the net charge on each adduct differs from that of each corresponding polyionic molecule; and

analyzing the collection of adducts by mass spectrometry.

17. A method of claim 2 wherein the step of attaching comprises reducing the net charge on at least one of the adducts to a value of 0.