Phosphonium-based ionic liquids and uses

1. A matrix for matrix-assisted laser desorption ionization mass spectrometry, said matrix comprising a composition of the formula [PR 4 ] m [X] n , said composition being a molten salt with a melting temperature below 100° C., wherein m is 1 or 2 and n is 1, wherein each R is a group that comprises 4-22 carbons and is independently selected from alkyl, alkenyl, alkynyl, phenyl, and aryl, wherein X is an anion selected from 2,5-dihydroxybenzoate, α-cyano-4-hydroxycinnamate, ferulate, and a dye anion selected from

2. A matrix for matrix-assisted laser desorption ionization mass spectrometry, said matrix comprising a composition of the formula [PR 4 ] m [X] n , said composition being a molten salt with a melting temperature below 100° C., wherein m is 1 or 2 and n is 1, wherein [PR 4 ] is selected from trihexyltetradecylphosphonium, triisobutyl(methyl)phosphonium, tributyl(methyl)phosphonium, tributyl(hexadecyl)phosphonium, tetrabutylphosphonium, tetraoctylphosphonium, tetradecyl(tributyl)phosphonium, ethyl(tributyl)phosphonium), tributyl(methyl)phosphonium, triisobutyl(methyl)phosphonium, triisobutyl(ethyl)phosphonium, triethyl(methoxyethyl)phosphonium, tri(isobutyl)methylphosphonium, triethyl[2-(2-methoxyethoxy)ethyl]phosphonium, tetraphenylphosphonium, butyltriphenylphosphonium, trihexylmethylphosphonium, and trihexyl(ethyl)phosphonium, wherein X is an anion selected from 2,5-dihydroxybenzoate, α-cyano-4-hydroxycinnamate, ferulate, and a and a dye anion selected from

3. The matrix of claim 1 , wherein [PR 4 ] is trihexyltetradecylphosphonium.

4. A kit for preparing a sample of a soluble analyte in a matrix for analysis by matrix-assisted laser desorption ionization mass spectrometry, said kit comprising a compound of the formula [PR 4 ] m [X] n wherein m is 1 or 2, wherein n is 1, and wherein each R is a group that comprises 4-22 carbons and is independently selected from alkyl, alkenyl, alkynyl, phenyl, and aryl, wherein X is an anion selected from 2,5-dihydroxybenzoate, α-cyano-4-hydroxycinnamate, ferulate, and a dye anion, the dye anion selected from

instructions for preparing a sample of a soluble analyte in a matrix for analysis by matrix-assisted laser desorption ionization mass spectrometry, wherein said compound is the matrix for the soluble analyte.

5. A kit for preparing a sample of a soluble analyte in a matrix for analysis by matrix-assisted laser desorption ionization mass spectrometry, said kit comprising a compound of the formula [PR 4 ] m [X] n wherein m is 1 or 2 wherein n is 1 and wherein [PR 4 ] is selected from trihexyltetradecylphosphonium, triisobutyl(methyl)phosphonium, tributyl(methyl)phosphonium, tributyl(hexadecyl)phosphonium, tetrabutylphosphonium, tetraoctylphosphonium, tetradecyl(tributyl)phosphonium, ethyl(tributyl)phosphonium), tributyl(methyl)phosphonium, triisobutyl(methyl)phosphonium, triisobutyl(ethyl)phosphonium, triethyl(methoxyethyl)phosphonium, tri(isobutyl)methylphosphonium, triethyl[2-(2-methoxyethoxy)ethyl]phosphonium, tetraphenylphosphonium, butyltriphenylphosphonium, trihexylmethylphosphonium, and trihexyl(ethyl)phosphonium, wherein X is an anion selected from 2,5-dihydroxybenzoate, α-cyano-4-hydroxycinnamate, ferulate, and a dye anion, the dye anion selected from

instructions for preparing a sample of a soluble analyte in a matrix for analysis by matrix-assisted laser desorption ionization mass spectrometry, wherein said compound is the matrix for the soluble analyte.

6. The kit of claim 4 , wherein PR 4 is trihexyltetradecylphosphonium.

7. A composition of the formula [PR 4 ] m [X] n wherein m is 1 or 2, wherein n is 1, wherein each R is a group that comprises 4-22 carbons and is independently selected from alkyl, alkenyl, alkynyl, phenyl, and aryl, wherein X is an anion selected from 2,5-dihydroxybenzoate, α-cyano-4-hydroxycinnamate, ferulate, and a dye anion, the dye anion selected from

8. A composition of the formula [PR 4 ] m [X] n (wherein m is 1 or 2, wherein n is 1, wherein [PR 4 ] is selected from trihexyltetradecylphosphonium, triisobutyl(methyl)phosphonium, tributyl(methyl)phosphonium, tributyl(hexadecyl)phosphonium, tetrabutylphosphonium, tetraoctylphosphonium, tetradecyl(tributyl)phosphonium, ethyl(tributyl)phosphonium), tributyl(methyl)phosphonium, triisobutyl(methyl)phosphonium, triisobutyl(ethyl)phosphonium, triethyl(methoxyethyl)phosphonium, tri(isobutyl)methylphosphonium, triethyl[2-(2-methoxyethoxy)ethyl]phosphonium, tetraphenylphosphonium, butyltriphenylphosphonium, trihexylmethylphosphonium, and trihexyl(ethyl)phosphonium, wherein X is an anion selected from 2,5-dihydroxybenzoate, α-cyano-4-hydroxycinnamate, ferulate, and a dye anion, the dye

9. The composition of claim 7 , wherein PR 4 is trihexyltetradecylphosphonium.

10. A composition of the formula [PR 4 ] m [X] n wherein m is 1 or 2, wherein n is 1, wherein each R is a group that comprises 4-22 carbons, wherein each R is independently selected from linear alkyl, branched alkyl, cycloalkyl, linear alkenyl, branched alkenyl, cycloalkenyl, phenyl, aryl, linear alkynyl, and branched alkynyl, wherein X is selected from all-trans-retinoate, iodate, anthraquinone-2-carboxylate, 7-hydroxycoumarinyl-4-acetate, aurintricarboxylate, 3,6-dihydroxyflavone, 9-hydroxy-9-fluorenecarboxylate, 2-(4-hydroxyphenylazo)benzoate, mellitate, 2,3-napthalenedicarboxylate, curcuminate, sinapate, succinate, 2-(4-hydroxyphenylazo)benzoate, caffeate (3,4-dihydroxycinnamate), nicotinate, anthranilate, trans-3-indoleacrylate, picolinate, or 3-hydroxypicolinate, said composition having a melting temperature of less than 100° C.