Open Access Philosophy

Our intension is to make mass spectrometry available to as many people as possible on a 24/7 basis.
 
We cannot promise you success but one thing is certain: if you do not give it a try you are guaranteed not to get a result!
 
Mass spectrometry has long been a technique of last resort, particularly in synthetic chemistry, as a result of the need for specialized instrument operators and the slow turn around time that was often encountered. This meant that MS was often relegated to the end of a sample characterization sequence that included TLC, NMR, IR and finally MS, with the requirement to obtain an accurate mass measurement for the data to be publishable being the driving force for the analysis.
 
The advent of ESI, autosamplers and appropriate software has meant that MS can be moved to the front of the analytical chain, even ahead of TLC. As such the instrumentation can be used by anybody with relatively little training.

Open Access Small Molecule Analysis

The facility specializes in offering an ‘Open Access’ format for many users. This format is based on a combination of specific software and the use of autosamplers for sample introduction. Instruments in this format are available on a 24/7 basis.
 
Open Access instruments include:
ESI-TOF-MS (2 instruments) in flow injection mode (FIA)
ESI-TOF-MS with reversed phase (C18) LC
ESI-QqQ-MS/MS with reversed phase (C18) UPLC
GC-MS (2 instruments) with EI and CI (Ammonia reagent gas)
MALDI-TOF/TOF

Small molecule sample preparation – polar molecules:
Polar molecules are analyzed using ESI (usually one or two heteroatoms are sufficient to obtain an adequate response)
Approximately the amount used in a TLC analysis can be used to prepare an ESI sample.
For FIA the sample should be dissolved in methanol in a 7 x 40 mm ‘mass spec’ vial. We recommend obtaining a bag of vials from PS stores and a bottle of high purity methanol (that you keep hidden so that it does not get contaminated).
For LC-MS try to have a more aqueous solvent mix if possible, e.g. 1:1 acetonitrile:water

ESI results:
For the most part ESI generates molecular weight information usually as [M + Na]+, i.e., a sodiated ion. Other ions may also occur including [M + H]+, [M + NH4]+, [M + K]+,  

Small molecule sample preparation – non-polar molecules:
Non-polar molecules are analyzed using GC-MS (‘one polar group good, two polar groups bad and don’t run acids’ is a reasonable indicator of when GC-MS is applicable with –OH and NH2 as the relevant polar groups).
Samples should be dissolved in a non-polar solvent, e.g., alkanes, ether, benzene, dichloromethane, chloroform or ethyl acetate. Do NOT use acetonitrile, any alcohol, or water.
Sample concentration should be about 50µg/mL. This is pretty concentrated but usually is a good starting point.

GC-MS results:
EI (electron ionization) is an energetic process that uses 70 eV electrons with a consequence that there is often extensive fragmentation of the analyte even to the point that the molecular ion may not be observed. When seen the molecular ion occurs as [M]+, i.e. the molecular weigh of the ion without any adducted species.
CI (chemical ionization). We use ammonia as the reagent gas so ions formed are typically [M + H]+ or [M + NH4]+ with minimal fragmentation. 
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