Suport
All users should use these sample preparation guidelines in order to improve the quality of the results. If you have any questions, do not hesitate to contact the Mass Spectrometry Center
Mass Spectrometry of small molecules
- Mass spectrometry is a
powerful analytical tool. However, impurities and
contaminants are especially important as
signal intensity and spectra quality depends mainly on the quality
of samples.
Thus,
proper sample preparation is one of the keys to
maintain a successful mass spectrometric assay.
- It is important that you can estimate the
amount of sample submitted for MS analysis.
From a practical point of view,
for ESI experiments, we prefer
that you submit ~1 mg. However this is not
required.
- Check the solubility
the compound
you are submitting for MS analysis. Solvents
commonly used in Mass Spectrometry are dichloromethane, methanol,
acetonitrile and water. If
a preferred solvent is not mentioned, Methanol will be
used as solvent
for MS
analysis.
- The
presence of salts or surfactants can suppress the signal for other
components. If your sample contains salts,
contact the Mass Spectrometry Center.
Samples with phosphate salts can not be analyzed be ESI-MS.
Proteomic s
-Our proteomics service
includes in-gel and/or in-solution proteolytic digestion, ESI-QEXACTIVE
(MS and MS/MS) for the identification of proteins based on database
searching. Under request our services includes peptide separation
by liquid chromatography before MS analysis.
- By routine for in-gel proteins identification, samples submitted as
gel slices are de-stained using appropriate protocols and
proteins are digested with
trypsin overnight (other enzymes can be used, please contact the
Mass Spectrometry Center).
- Data obtained is searched against predicted fragments from the
trypsin digestion of proteins contained in a database using Protein discoverer.
- We encourage the use of Coomassie or colloidal blue stain.
Other stains are possible but please contact first the Mass
Spectrometry Center for advice.
- Please note that extreme caution has to be used to avoid
contamination with keratin, especially for low level protein sample. To avoid contamination with keratin wear powder free latex gloves
all the time when processing the samples.
Samples can be submitted:
In-gel:
an excised band from a gel. The band should be cut using extreme
caution to avoid keratin contamination. A band that can be
visualized by Coomassie stain, usually contains sufficient protein
for identification.
In solution:
samples can be submitted in solution (10-20 µl). Avoid any
detergents and unnecessary sample buffers.
Pre-digested samples:
a pre-digested sample can be submitted for analysis by using the
protocols used in the Mass Spectrometry Center.
-Sample submission procedure-
Gel samples submission:
- Minimize
keratin contamination.
Remember to work in a clean
air environment, clean the bench; always use powder free latex
gloves, brand new pipette tips, razor blades and tubes
- Gel bands
should be ~1 x 5mm; gel spots should be ~2mm
diameter.
- Place in
1.7mL eppendorf tube covering gel pieces with 0.01%
acetic acid.
- Specify
source organism and fill our request service form.
Protein solution sample
submission:
- Buffer
composition.
The solution background
should be water or < 50mM volatile salt (e.g. TEAB) and when
possible avoid detergents, surfactants and non-volatile salts.
- Ship
proteins refrigerated or lyophilized.
- Specify
source organism and fill our request service form.
