Surface chemical analysis of carbohydrate materials used for chromatography media by time-of-flight secondary ion mass spectrometry.

The surface chemical structure of two raw materials (agarose and dextran) and four base matrixes used in the manufacture of chromatography media were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results show that the small differences in molecular structure between these materials result in significant differences in the TOF-SIMS spectra and that these differences can be identified and quantified using either of two different approaches. In a novel approach, fragment ion distributions were extracted from the TOF-SIMS spectra for each material, providing an immediate and systematic overview of the spectral features. Difference fragment distributions were used to highlight spectral differences between the materials. The results of the fragment ion distribution analysis, in terms of identification and quantification of spectral variations between different materials, were found to be in agreement with the results from a principal component analysis using the same set of data. Both methods were found capable of (i) distinguishing between agarose and dextran and (ii) detecting and quantifying the degree of cross-linking present in the four base matrix materials. In addition, using a deuterated chemical cross-linker, it was possible to identify spectral features specifically connected to the cross-link molecular structure.