Dicationic liquid salts and methods of use thereof
Dicationic liquid salts and methods of using such dicationic liquid salts in techniques such as ESI-MS are provided.
1. A method of detecting at least one charged analyte in a sample by ESI-MS, the method comprising:
adding to the sample at least one dicationic liquid salt comprising a dicationic species corresponding in structure to Formula I:
and at least one counter-anion, wherein the at least one counter-anion comprises OH − , and
detecting a complex formed between the at least one charged analyte and the dicationic species of the at least one dicationic liquid salt using ESI-MS,
wherein:
X is phosphonium substituted with one or more substituents independently selected from the group consisting of methyl, ethyl, propyl and butyl; and
B is C 1 -C 12 -alkylene or —CH 2 -phenyl-CH 2 —, wherein C 1 -C 12 -alkylene optionally contains in the chain one or more oxygen atom.
2. The method of claim 1 , wherein the dicationic species is selected from the group consisting of:
3. The method of claim 1 , wherein the ESI-MS is carried out in the positive ion mode.
4. The method of claim 1 , wherein the charged analyte comprises an anion having a charge of −1, wherein the charged analyte pairs with the dicationic species to form a complex having a net positive charge.
5. The method of claim 1 , wherein the dicationic liquid salt is added to a carrier flow solvent.
6. The method of claim 5 , wherein a dicationic liquid salt solution of about 1 μM to about 200 μM is added to the carrier flow solvent.
7. The method of claim 5 , wherein the carrier flow solvent is a water-miscible organic solvent or a mixture of water and the water-miscible organic solvent.
8. The method of claim 7 , wherein the water-miscible organic solvent is selected from the group consisting of methanol, ethanol, propanol, acetonitrile, tetrahydrofuran and dioxane.
9. The method of claim 1 , further comprising coupling ESI-MS with a separation technique.
10. The method of claim 9 , wherein the separation technique is selected from the group consisting of liquid chromatography, HPLC, ion chromatography, ion-exchange chromatography, SPE, SPME, TS-SPME and SPME/MALDI.
11. The method of claim 9 , wherein the dicationic liquid salt is added to the carrier flow solvent following the separation technique.
12. A method of detecting at least one charged analyte in a sample by ESI-MS, the method comprising:
adding to the sample at least one dicationic liquid salt comprising a dicationic species selected from the group consisting of:
and at least one counter-anion; and
detecting a complex formed between the at least one charged analyte and the dicationic species of the at least one dicationic liquid salt using ESI-MS.
13. The method of claim 12 , wherein the at least one counter-anion is F − .
14. The method of claim 12 , wherein the at least one counter-anion is OH − .
15. The method of claim 12 , wherein the ESI-MS is carried out in the positive ion mode.
16. The method of claim 12 , wherein the charged analyte comprises an anion having a charge of −1, and wherein the charged analyte pairs with the dicationic species to form a complex having a net positive charge.
17. The method of claim 12 , wherein the dicationic liquid salt is added to a carrier flow solvent.
18. The method of claim 17 , wherein a dicationic liquid salt solution of about 1 μM to about 200 μM is added to the carrier flow solvent.
19. The method of claim 17 , wherein the carrier flow solvent is a water-miscible organic solvent or a mixture of water and the water-miscible organic solvent.
20. The method of claim 19 , wherein the water-miscible organic solvent is selected from the group consisting of methanol, ethanol, propanol, acetonitrile, tetrahydrofuran and dioxane.
21. The method of claim 12 , further comprising coupling ESI-MS with a separation technique.
22. The method of claim 21 , wherein the separation technique is selected from the group consisting of liquid chromatography, HPLC, ion chromatography, ion-exchange chromatography, SPE, SPME, TS-SPME and SPME/MALDI.
23. The method of claim 21 , wherein the dicationic liquid salt is added to the carrier flow solvent following the separation technique.