Compositional analysis and quantification of heparin and heparan sulfate by electrospray ionization ion trap mass spectrometry

A new method using a combination of electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MSn) was developed for the identification and quantitative analysis of eight heparan sulfate (HS)- and heparin-derived delta-disaccharides obtained by enzymatic depolymerization. The compositional analysis of nonisomeric disaccharide constituents of heparin/HS was achieved from full-scan MS1 spectra using an internal standard and a calculated response factor for each disaccharide. Diagnostic product ions from MSn spectra of isomeric disaccharides were used for the quantitative analysis of the relative amounts of each of the isomers in mixtures. The protocol was validated using several quality control samples and showed satisfactory accuracy and precision. The analysis is rapid, accurate, and uses no purification or separation steps prior to analysis by MS, thus reducing sample consumption and analysis time of traditional methods. Using this quantitative analysis procedure, percentages of disaccharide compositions for heparins from porcine and bovine intestinal mucosa and heparan sulfate from bovine kidney were determined.