Enrichment of nitrophenols in water by off- and on-column concentration for capillary electrophoresis

Abstract

A method based on the combined use of off-column solid phase extraction (SPE) using C18 membrane disk and on-column field amplified injection (FAI) was developed to isolate, recover, and concentrate nitrophenols in river water prior to analysis by capillary electrophoresis (CE). The effect of eluent, sample pH, and volume in SPE, sample solvent and injection volume in FAI, and the combination of SPE and FAI was investigated in order to find optimal conditions for overall enrichment. With the use of SPE combined with FAI, extraction time was reduced, most interferences were removed, limit of detection was decreased to 5-10 ppb, and recovery of each nitrophenol was > 80%. Combination of off-column SPE and on-column FAI provides a rapid and selective approach for quantitatively concentrating nitrophenols in river water at ppb level prior to CE analysis.