The following guidelines will be helpful and should be followed when you prepare samples for mass spectrometric analysis.

Solvents:

  • In general, volatile, low MW protic solvents are preferred, such as acetonitrile, methanol, isopropanol, ethanol and water. In the LC-ESI-MS analysis, methanol/water (1:1) is the default solvent.
  • If water is required for solubility, up to 50% water may be added.
  •  Avoid using:
    * Tris, phosphates, citrates and HEPES
    * Urea and guanidinium salts
    * Trifluoroacetic acid (TFA) causes signal supression, and should be kept below 0.1%. Commonly used alternatives to high concentrations of TFA are mixtures of either 1% acetic or 0.1% formic acid with 0.025% TFA.
    * Detergents such as SDS, CHAPS, PEG, Tween, and Triton
    * DMSO, DMF, THF, acetates and glycerol
    * Hydrocarbon solvents, such as hexane and benzene, are not amenable to ESI

Concentration and Volume:

A reasonable sample concentration is critical to a successful analysis, and extremely low or extremely high concentrations have detrimental effects. For electrospray analysis, please submit 50ul of (at least) 10pmol/ul sample solution. For MALDI analysis, please submit at least 1mg of purified solid sample or 50ul of (at least) 10pmol/ul sample solution. The samples should be submitted in polypropylene microcentrifuge tubes/vials or deactivated glass vials with teflon-lined screw caps. Use a small volume insert if a limited amount of sample is available. All sample tubes/vials must be labeled with a sample ID and be accompanied by a Sample Submission Form (PDF or MS-Word) .

 

How to Choose an Appropriate Ionization Method for Your Compounds:

Please refer to the following descriptions of the ion sources:

MALDI

ESI

APCI

DART

EI

CI

FAB

Ionization Mechanism

Ionization Method Comparison

 

Please contact the facility if you have any questions or concerns regarding preparation and analysis of your samples.

 

Print Friendly