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Peptide/Protein Molecular Weight Determination


Peptide and/or  protein  molecular weight determination among other biopolymers can be determined at the mass spectrometry facility in IMSERC. An Agilent 6220A Time-of-Flight LCMS system (resolving power of ~10,000) is used to perform an online sample clean up by liquid chromatography followed by electrospray ionization, high resolution mass spectrometric analysis. The complexity of the raw data (due to significant contribution from adjacent molecular isotopes under each one of the charge state ion envelope) makes it nearly impossible to manually interpret the data. Maximum Entropy algorithm is utilized to deconvolute the data into a simple neutral spectrum where each unique molecule is assigned a single Mr. Relatively small biopolymers of up to 150 kDa has been successfully analyzed.

Typical Data

Below are spectra of raw (left), deconvoluted data (middle), and a zoomed inm spectrum showing potential modifications to the specific biopolymer.



  • Determine the molecular weight of a peptide or protein of interest.
  • Detect impurities in sample. These could be synthetic impurities or impurities that arise from purification or expression of the protein or peptide.
  • Identify / confirm modifications to peptide or protein. These could be expected, desired, or unknown.

If you are interested in utilizing any of these applications for your research Start a project