Modification and cross-linking parameters in hyaluronic acid hydrogels--definitions and analytical methods.

Definitions and methods for the quantification of degree of modification and cross-linking in cross-linked hyaluronic acid (HA) hydrogels are outlined. A novel method is presented in which the HA hydrogel is degraded by the enzyme chondroitinase AC and the digest product analyzed by size exclusion chromatography combined with electrospray ionization mass spectrometry (SEC-ESI-MS). This method allows for the determination of effective cross-linker ratio (CrR) which together with the degree of modification (MoD), determined by, e.

Fingerprinting metal-containing biomolecules after reductive displacement of iron by gallium and subsequent column-switched LC-ICPMS analysis applied on siderophores.

Column-switching liquid chromatography followed by low-resolution ICPMS was evaluated as a tool for speciation analysis of metal-containing biomolecules. The strategy was applied on siderophores, strong iron chelators of low molecular weight (M(w) < 1500). Prior to the LC-ICPMS analysis, reductive displacement of iron by gallium was performed using ascorbate as the reducing agent to increase the sensitivity.