Utilization of MS3 spectra for the multicomponent quantification of diastereomeric N-acetylhexosamines.

A rapid and accurate means of quantifying mixtures of diastereomeric N-acetylhexosamine monosaccharides using MS3 product ions is introduced. The method involves derivatizing the monosaccharides with [Co(DAP)2Cl2]Cl (where DAP is diaminopropane), and subjecting the derivatized products to collision-induced dissociation (CID) in a quadrupole ion trap mass spectrometer. Each diastereomer provides unique MS3 product ion abundances. The abundances for the pure monosaccharide standards are used in a system of equations in order to quantify mixtures of these diastereomers. Using the system of equations is quite advantageous, as it is the only mass spectrometric method that has been shown to successfully quantify mixtures of more than two isomers. The utility of the method is demonstrated by successfully quantifying various two and three component mixtures of the diastereomeric monosaccharides. Furthermore, the method is used to quantify the recovery of a single diastereomeric monosaccharide from an acidic resin. Although the multicomponent quantification method described herein is used to quantify mixtures of N-acetylhexosamine diastereomers, it could be applied to any group of isomers, provided distinguishing CID spectra are obtained. This is the first known report of utilizing MS3 product ions for quantification of structural isomeric mixtures.