
Preparing Samples
Voyager
™
Biospectrometry
™
Workstation User’s Guide 3-19
3
3.1.5 Sample Cleanup
Cleaning
techniques
Use the following techniques to clean samples:
• Washing
• Drop dialysis (floating membrane)
• Cation exchange
•ZipTips
®
When to clean
samples
Sample cleanup is needed if samples:
• Are prepared in phosphate buffers. Ammonium salts or
derivatives of organic amines (ammonium bicarbonate,
TRIS HCl) do not usually cause a problem in low
concentrations (less than 50mM).
• Contain salt, for example, from cation or anion exchange
purification.
• Are contaminated with detergent.
Symptoms that indicate the need for sample cleanup include:
• Poor crystallization on the sample plate.
• Large tail on the high mass side of peaks, which may be
unresolved salt or buffer adducts.
• Poor sensitivity with a sample concentration that should
yield a strong signal. To detect this condition, mix the
sample with a standard that you know yields a strong
signal. If the standard no longer exhibits the expected
signal, a contaminant in the sample is affecting sensitivity.
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