Services Overview

Mass spectrometry service

Knowledge of the molecular weight and molecular formula are the two most important pieces of information when an unknown compound must be identified. The molecular weight as well as the molecular formula can be determined by mass spectrometry but a confident identification of the molecular formula will typically require measurements at higher resolution than that required for a molecular weight determination..
The molecular formula is determined from an accurate mass measurement of a monoisotopic peak. However, the number of different molecular formulas within a given mass window increases rapidly with the molecular weight which means that as the molecular weight of the unknown increases, the resolution of the measurement must also be increased.
With ESI the high resolution measurements at epiZell are carried out with a Waters Q-Tof Premier which has a resolving power of 3 ppm and where the accuracy is ensured by alternating measurements of sample and standard (lock spray).
The validity of the results, and the mass range over which the molecular formulas can be determined are enhanced by doing the data analysis with MassWorks, in which analyses of the isotopic patterns and the peak-shapes are included in the selection of the unknown molecular formula.
Our MALDI analyses are carried out on a Waters Q-Tof Global.
MS-MS analyses with collisional activation can be carried out with both MALDI and ESI ionization.