Instructions for Sample
Submission
Mass
range consideration
Electron impact (EI) MS: 50-800 Da,
Low resolution ESI MS: 50- 2000 Da.
High resolution ESI MS: 50-70,000 Da
High resolution MALDI MS: 600-40,000Da
High resolution MS/MS: 100-6000 Da
Selecting
an ionization method
EI: Stable, volatile samples (under high vacuum, up to heat at
350 degrees)
ESI: Complex (such as organometallic compounds), non-volatile,
thermally labile or unstable samples.
MALDI: organic polymers and biomolecules.
MS samples are normally analyzed in the positive ionization mode
because of high sensitivity, except some analyses of organic
acids, sugars, nucleic acids have to be performed in negative
ionization mode.
Solubility of
organic compounds
Although EI MS samples can be submitted in either solid or
liquid form, ESI MS analysis needs a soluble sample to be tested
prior to submission. The best solvents used in MS analyses are
recommended to be methanol, water,
acetonitrile, or their combination, and samples dissolved in
THF, methane chloride, DMSO are also acceptable.
Protein
samples
Proteins should be desalted with a dialysis in 10 mM ammonium
bicarbonate solution or centrifugal filter in an appropriate MW
cut-ff membrane tube. Coomassie stained gel bands of proteins
from SDS-PAGE gels are submitted in centrifugal tubes without
water, and labeling of sample names must be clearly present.
Please note the facility will
not accept Biohazardous or Radiolabeled samples.
