ANION SELECTIVITY OF A SAPPHYRIN-MODIFIED SILICA-GEL HPLC SUPPORT

A sapphyrin-modified silica gel support for use in highperformance liq uid chromatography was prepared by attaching a sapphyrin monocarboxyli c acid to aminopropyl silica gel through an amide bond. The anion rete ntion characteristics of this modified silica gel were tested by explo ring the extent to which a specific anion in the mobile phase would ac t to affect the rate at which AMP was eluted from an HPLC column conta ining this functionalized stationary phase. In general, it was found t hat phosphate and arsenate anions were more effective as eluents than carboxylic acids and halides, a result that was interpreted in terms o f these former species binding better to sapphyrin (and hence being mo re effective in terms of displacing AMP) than other anions tested. Sup port for the contention that phosphate anions will bind to sapphyrin s ubunits covalently tethered to the silica gel came from solid state P- 31 NMR spectroscopic analyses. These revealed that the P-31 nucleus un dergoes a 5 ppm upheld shift, relative to control, when allowed to int eract with the sapphyrin-containing support.