Separation and direct UV detection of sugars by capillary electrophoresis using chelation of copper(II)

A new method for the capillary electrophoretic separation of neutral sugars with direct UV detection based on the chelation reaction with copper (II) is demonstrated. Using an electrolyte consisting of copper(II) sulphate and ammonia, UV absorption at 245 nm results from the chelation of Cu(II) by the sugars under alkaline conditions. In addition, the sugar mobility increases with increasing Cu(II) concentration in the electrolyte. Thus, the chelation with Cu(II)provides both separation and direct UV detection of neutral sugars. Detection limits for sugars in the range of 50-100 mu M are achieved. Linearity over two orders of magnitude is observed. Furthermore, using the same electrolyte, the simultaneous detection of amino acids due to complexation with Cu(II) and the indirect detection of inorganic cations is possible. (C) 1998 Elsevier Science B.V.