Intact Molecular Weight Analysis

Intact molecular weight analysis is used for quick confirmation of peptide or protein identity, or for detecting potential modifications, disulfide bonds, impurities or degradants within a sample.

The Proteomics Core's mass spectrometry approach utilizes electrospray ionization (ESI) combined with a time-of-flight (TOF) detector to provide high-accuracy — plus or minus 0.01 to 0.02 percent — mass measurement over a wide molecular weight range at a nominal level of sample consumption (only 1 to 10 picomoles).

There are two sample-introduction platforms available: direct infusion, which is used for a purified peptide or protein sample, and in-line liquid chromatography (LC) separation, which is used for a complex mixture.


  • Direct infusion ESI-TOF. A purified sample is introduced into the ESI source in a liquid stream containing an organic modifier and an acid delivered from a syringe pump or as an LC effluent.

    Samples can be submitted in dry or liquid form and must be void of nonvolatile salts, detergents and glycerol, as these will interfere with the detection of the peptide or protein. For an additional fee, the core can conduct sample preparation.

  • LC-ESI-TOF. Multiple components in a complex mixture are separated on a reversed-phase LC column prior to introduction into the ESI source. Retention time and assigned molecular weight of the eluting peaks are used to identify the peptide or protein of interest, as well as impurities or degradants.

    The length of the analysis depends on the complexity of the sample. Samples can be submitted in dry form or with amenable LC solvents.


For this service, costs are determined on a fee-per-sample basis. Sample preparation may result in additional costs.


For more information or to initiate a service or project request, email the Proteomics Core.