INTERFACE FOR COUPLING CAPILLARY ELECTROPHORESIS TO INDUCTIVELY-COUPLED PLASMA AND ON-COLUMN CONCENTRATION TECHNIQUE

A new interface for coupling capillary electrophoresis (CE) to inducti vely coupled plasma (ICP) was developed. The interface was built outsi de and independent of the nebulizer and could be easily connected with a microconcentric nebulizer (MCN) as well as conventional pneumatic n ebulizers. An on-column concentration technique was used to increase t he sensitivity and to enhance the resolution of the system of capillar y electrophoresis-inductively coupled plasma atomic emission spectrome try (CE-ICP-AES). By doing this, it was possible to analyze 1 mu g/mL of total chromium (prepared with K2Cr2O7 and CrCl3) and 1 mu g/mL of c opper consisting of CU2+ and Cu(EDTA)(2-) with good spectroscopic inte nsity and efficient separation. Detection limits of 18 elements for MC N-ICP-AES coupled with CE were assessed by continuous sample introduct ion without applying high voltage and were found to be 1-4 times highe r than those typically obtained by using MCN-ICP-AES for elemental ana lysis (without connection to the CE interface). When the on-column con centration technique was used, the sensitivities and separations were further improved by increasing the amount of sample. A simple electrol yte (0.05 M HNO3) and a large inner diameter capillary (150 mu m) coul d also be used to attain efficient separation.