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

A rapid and accurate means of quantifying mixtures of diastereomeric N-acet ylhexosamine monosaccharides using MS3 product ions is introduced. The meth od involves derivatizing the monosaccharides with [Co(DAP)(2)Cl-2]Cl (where DAP is diaminopropane), and subjecting the derivatized products to collisi on-induced dissociation (CID) in a quadrupole ion trap mass spectrometer. E ach 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 equ ations is quite advantageous, as it is the only mass spectrometric method t hat has been shown to successfully quantify mixtures of more than two isome rs. The utility of the method is demonstrated by successfully quantifying v arious two and three component mixtures of the diastereomeric monosaccharid es. Furthermore, the method is used to quantify the recovery of a single di astereomeric monosaccharide from an acidic resin. Although the multicompone nt quantification method described herein is used to quantify mixtures of N -acetylhexosamine diastereomers, it could be applied to any group of isomer s, provided distinguishing CID spectra are obtained. This is the first know n report of utilizing MS3 product ions for quantification of structural iso meric mixtures. (J Am Soc Mass Spectrom 2000, 11, 1086-1094) (C) 2000 Ameri can Society for Mass Spectrometry.