Intact protein mass analysis 0-50 kDa

Molecular Weight Determination by MALDI-MS

MALDI-MS analysis is a very good and fast technique for molecular weight determination. We use it to determine the intact mass weight for proteins up to 50 kDa. The main advantage of MALDI-MS intact mass analysis is you can interpret the full mass spectrum without any deconvolution step. The analysis therefore gives a good indication of purity and complexity of protein and peptide samples. Contrarily, we use ESI-MS analysis for proteins up to 250 kDa.

Choose your service

Our Fast Protein Analysis Services are without customization. You get quality results in easy to understand standard reports, at fixed prices.

Option 1

Intact mass by MALDI-MS

  • Mass range 0-50 kDa
  • Accuracy within 50 ppm
  • Sample amount >5 ug
Per sample
Results in 4-8 days
Option 2

Intact mass by MALDI-MS (compared to theoretical MW)

  • Mass range 0-50 kDa, accuracy within 1-2 Da
  • Sample amount >5 ug
  • Comparison with theoretical MW
Per sample
Results in 4-8 days
Service includes
  • The accuracy on this service lies within 50 ppm (+/- 1 Dalton for a 20 kDa protein).
  • Results in 4-8 days.
  • The report lays out the data in a way that is easy to read and understand.


Graph showing intact mass curve

Intact mass (MW determination) of protein by MALDI-MS



Our customers typically use this analysis for the following applications:

Compare samples – for example batch to batch variation

Determine the purity of your sample

Look for modification such as glycosylations, acetylations, oxidations, etc.

Compare with theoretical MW

Sample requirements

Protein and peptide samples can be submitted in liquid or as lyophilized material.

The chromatographic protein/peptide purity should be >90%
Avoid detergents and keep buffer concentration at a minimum. MALDI-MS analysis can be done on samples containing small amounts of salts, urea or detergent, but the best result are obtained with low buffer strength in volatile solvents without detergents
Minimum amount ~ 10-50 micrograms

Please note that MW determination of intact proteins by mass spectrometry CANNOT be conducted on samples from SDS gels or from PVDF membranes!

Technical details

In MALDI-MS, the dissolved sample is deposited on a metal target and the peptides and proteins are co-crystallized with a light-absorbing matrix. A laser beam is directed at the dry matrix sample, the sample molecules are desorbed and ionized and the masses are measured in a time-of-flight (TOF) mass analyzer. Proteins are observed in the mass spectrum (mass-over-charge spectrum, m/z) as singly (m/z MH+) as well as multiple charged ions.

Sample preparation and data analysis
Sample is mixed with 2,5-dihydroxyacetonphonone/diammonium hydrogen citrate (DHAP/DAHC) matrix and spotted onto a Big Anchor target from Bruker. Mass spectra are acquired on an Autoflex Speed MALDI TOF/TOF mass spectrometer in linear mode using Compas 1.4 control and processing software. The mass spectra are calibrated by external quadratic calibration using Bruker Protein Calibration Standard 1. The sample mass is calculated from the least charged ion within the calibrated range of the mass spectrum.

Have questions? We'd love to help.

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