POTENTIOMETRIC DETECTION IN CAPILLARY ELECTROPHORESIS WITH A METALLICCOPPER ELECTRODE

A copper metal electrode is used as potentiometric detector ibr capill ary electrophoresis. The detector response is based on the complexatio n of copper ions at the electrode surface, which leads to a decrease o f the electrode potential when the eluted analyte forms more stable co pper complexes than the running buffer. A mixture of nine underivatize d amino acids was separated within 7 min using basic carbonate and ber ate buffers as running electrolyte and detection was realised by poten tial measurement at a copper disk electrode in the wall-jet configurat ion. Calibration curves showed dynamic ranges of three orders of magni tude and detection limits of 5.9 x 10(-6) M for threonine and 3.2 x 10 (-6) M for lysine. (C) 1997 Elsevier Science B.V.