Ionization Technique Choices
Our lab’s instruments are capable of the following modern ionization techniques:
- Electrospray Ionization (ESI)
- Electron Ionization (EI)
- Chemical Ionization (CI)
- Matrix-Assisted Laser Desorption/Ionization (MALDI)
- Atmospheric Pressure Chemical Ionization (APCI)
- Dual Ion Source with ESI and APCI (DUIS)
Depending upon your sample type, one or more ionization techniques may be appropriate for your sample. If you have difficulty deciding on an ionization technique for your specific sample type, please do not hesitate to contact Dr. Kevin Tucker (email kevtuck@siue.edu).
Spectrum Choices
Full Scan
It may show the molecular ion and/or fragment ions. Masses are generally accurate to within a few tenths of a Da. A low resolution full scan is often the only mass spectrum you need. If you choose this type of mass spectrum, you should be sure to provide the mass range that you are interested in or the molecular weight that you are targeting.
MS/MS
If your compound does not fragment in the mass spectrometer and you wish to obtain fragmentation for structural determination, you need MS/MS (ESI and MALDI only). The most common use of MS/MS is for the sequencing of peptides. Prior to having MS/MS analysis performed, we require that you have a Low Resolution Scan done first. To provide MS/MS analysis, you need to indicate what peak(s) from your low resolution scan you would like to have fragmented.
Mixture
If your sample is a mixture and you want a mass spectrum of one or more components, you will need GC/MS (EI or CI) or LC/MS (ESI). In these techniques, the effluent is directed into the mass spectrometer, where a mass spectrum of each component is obtained as it elutes from the column.
Learn More About Gas Chromatography/Mass Spectrometry (GCMS) Learn More About Liquid Chromatography/Mass Spectrometry (LCMS)If you are not sure about your analysis needs, please contact Dr. Kevin Tucker (email kevtuck@siue.edu).
