Low/High Resolution - Accurate Mass Measurement (AMM)

Pechar

According to IUPAC, the resolution is defined by the formula:

Where DM is the resolving power (commonly, it is the width of the peak at 50 % of its height or FWHM Full Width at Half Maximum) and M the mass of the second peak or peak adjacent to the peak of interest. This indicates that the higher the resolution, the better the separation of the m/z peaks, thus distinguishing compounds with the same nominal mass, compounds with high molecular mass or with multiple charge, such as proteins, since the higher the charge, the smaller the distance between peaks.

The accuracy of the mass goes hand in hand with the resolution. At low resolution, an m/z ratio with an accuracy of up to one decimal place is obtained; at high resolution, an accuracy of up to four decimal places is obtained. Thus, with high resolution it is possible to perform the additional service of Accurate Mass Measurement (AMM), only available in this type of resolution, except in the MALDI technique, as they are not suitable for this task even though they can measure in high resolution.