DETERMINATION OF THE DIOL CONTENT OF CHROMATOGRAPHIC SUPPORTS BY CAPILLARY ELECTROPHORESIS

A capillary electrophoresis (CE) method was developed for determining the diol content of supports used in high-performance affinity or size exclusion chromatography. This method involved oxidizing the diol-bon ded support with periodate, followed by the use of CE to separate and quantitate the iodate produced by this reaction. Both the oxidation an d separation conditions were considered in optimizing this assay. The final method was performed by reacting a known amount of support with a 20-fold excess of periodate in pH 4.0, 0.5 M acetate buffer, with py romellitic acid being used as an internal standard. After allowing 5-1 0 min for oxidation, the mixture was filtered and the filtrate was inj ected onto a 57 cmx50 mu m I.D. fused-silica capillary operated at 25 kV and containing pH 4.0, 0.5 M acetate as the running buffer. The tot al separation time was 5 min per run and gave a detection limit of 0.1 mM iodate (or 0.1 mu mol diol groups) for a 6-nl injection of a 1-ml reaction mixture. By varying the amount the support that was assayed, this method could be used with either porous or non-porous supports. T his technique showed good correlation with an iodometric titration but required much less sample and time to perform.