What buffer should I use for MALDI mass spectrometry analysis of my protein sample?

Question:

What buffer should I use for MALDI Mass Spectrometry analysis of my protein sample?

Answer:

Although MALDI is more tolerant to contamination than other MS methods, the salts and detergents commonly used in biomolecular science can still interfere with either crystallisation or ionisation or both. Particular attention should therefore be paid to using sample purification and storage solvents which do not utilise buffers, salts or detergents such as SDS.

It is best to remove buffer salts and detergents (e.g. by dialysis) prior to analysis and to dissolve the sample in a suitable solvent (e.g. 0.1% TFA/water) which will not degrade the spectrum. If there is too much salt in a sample, the salt signal intensity is so large that it effectively suppresses out the sample signal, giving no sample spectrum. In cases where it is not possible to remove these contaminants the sample should be in a higher concentration. It may then be possible to dilute the sample to the point where the contaminants will have little effect on the spectrum.

One would normally like to have any sample in a volatile buffer not containing any salts and detergents. Examples of volatile buffer are ammonium acetate, acetonitrile, ammonium formate, TFA (trifluoroacetic acid) or formic acid in water.

Buffers not compatible with MALDI Mass Spec analysis of proteins include:

• TRIS
• PBS

 

Buffer components that will not work with Mass Spec analysis include:

• Tween 80
• Tween 20
• Triton X
• Glycerol
• DMSO
• SDS
• Sodium Azide

Learn more about all of our protein analysis and characterization services on our website: www.alphalyse.com

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