Preparation enhancements and methods of use for MALDI mass spectrometry
Provided herein are compositions and methods useful for preparing and analyzing a sample on a substrate by matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS). In some embodiments, compositions provided herein comprise a substrate, matrix and nanoparticles, and sometimes comprise one or more additives and sometimes an analyte. Compositions provided herein sometimes comprise nanoparticles that include or are made up of silicon dioxide.
1. A composition comprising a matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) matrix and nanoparticles, wherein:
there is substantially no ionic, hydrophobic, hydrogen bond or van der Walls association between the matrix and the nanoparticles, whereby the nanoparticles are not in association with the matrix and do not interfere with a signal generated by an analyte; and
the nanoparticles are not in association with a peptide or protein.
2. The composition of claim 1 , wherein there is substantially no covalent association between the matrix and the nanoparticles.
3. The composition of claim 2 , comprising substantially no component or components that covalently link the matrix with the nanoparticles.
4. The composition of claim 1 , wherein the matrix and the nanoparticles are in a liquid form.
5. The composition of claim 1 , wherein the matrix and the nanoparticles are in a solid form.
6. The composition of claim 5 , wherein the solid is crystalline.
7. The composition of claim 6 , wherein the crystals of the crystalline solid are substantially homogeneous.
8. The composition of claim 1 , wherein the matrix is suitable for mass spectrometry analysis of a nucleic acid.
9. The composition of claim 8 , wherein the matrix is 3-HPA.
10. The composition of claim 9 , wherein the matrix consists essentially of 3-HPA.
11. The composition of claim 1 that consists essentially of a single matrix component.
12. The composition of claim 1 , comprising multiple matrix components.
13. The composition of claim 1 , further comprising one or more additives.
14. The composition of claim 13 , wherein at least one additive is ascorbic acid.
15. The composition of claim 1 , wherein at least one additive is ammonium oxalate.
16. The composition of claim 14 , further comprising ammonium oxalate.
17. The composition of claim 16 , wherein the composition consists essentially of 3-HPA, ascorbic acid, ammonium oxalate and the nanoparticles.
18. The composition of claim 1 , wherein the nanoparticles have an average, mean, median, nominal, minimum or maximum diameter of about 5 nanometers to about 30 nanometers.
19. The composition of claim 18 , wherein the nanoparticles have an average, mean, median, nominal, minimum or maximum diameter of about 10 nanometers to about 20 nanometers.
20. The composition of claim 19 , wherein the nanoparticles have an average, mean, median, nominal, minimum or maximum diameter of about 15 nanometers.
21. The composition of claim 1 , wherein the nanoparticles substantially do not give rise to MALDI MS signals.
22. The composition of claim 1 , wherein the nanoparticles comprise SiO 2 .
23. The composition of claim 1 , wherein the nanoparticles comprise fumed silica particles.
24. The composition of claim 1 , wherein the nanoparticles are at a concentration of about 75 micrograms per milliliter to about 300 micrograms per milliliter in the solution.
25. The composition of claim 24 , wherein the nanoparticles are at a concentration of about 125 micrograms per milliliter to about 250 micrograms per milliliter in the solution.
26. The composition of claim 25 , wherein the matrix to nanoparticle mole ratio is about 225:1, 250:1 or 300:1.
27. The composition of claim 17 , wherein:
the nanoparticles have an average, mean, median, nominal, minimum or maximum diameter of about 5 nanometers to about 30 nanometers,
the nanoparticles comprise SiO 2 or fumed silica particles; and
the matrix to nanoparticle mole ratio is about 250:1 or 300:1.