Enrichment of Amino and Carboxylic Acids Using Copper-loaded Silica Pre-columns Coupled On-line with HPLC

Abstract

A novel method for preconcentrating amino and carboxylic acids on silica surfaces has been described. Two different copper-loaded silica surfaces, bis-dithiocarbamate-copper silica (Bdtc-Cu-Si) and cyclam-copper silica (Cy-Cu-Si) were prepared for this purpose. Bdtc-Cu-Si proved to be selective for amino acids, whereas, Cy-Cu-Si proved to be selective for carboxylic acids. These newly prepared surfaces showed good stability and strong binding properties toward organic compounds. Inorganic anions did not seem to show interference with amino acids, whereas, an excess of these ions interfere with the carboxylic acid pre-concentration. These surfaces were packed in pre-columns and then were coupled on-line with HPLC. Nanogram quantities of the organic compounds of interest may be determined using this technique.