Trivalent copper chelate-luminol chemiluminescence system for highly sensitive CE detection of dopamine in biological...

A transition metal chelate unstable at a high oxidation state, diperiodatocuprate (III) (K₅[Cu(HIO₆)₂], DPC), was synthesized and applied in the luminol-based chemiluminescence (CL) system for highly sensitive CE end-column detection of dopamine (DA). This method was based on the fact that DA enhanced the CL emission resulting from the reaction between luminol and DPC in alkaline medium. The DPC-luminol-DA CL system showed very intensive emission and very fast kinetic characteristics, thus resulting in a high sensitivity in flow-through detection mode for CE. Under optimal conditions, the linear range was 1.0 × 10⁻⁸-5.0 × 10⁻⁵ g/mL (R² = 0.9984) with a limit of detection of 6.0 × 10⁻⁹ g/mL (S/N = 3). The RSDs of the peak height and the migration time were about 4.2 and 2.4% for a standard sample at 3.0 × 10⁻⁶ g/mL (n = 5), respectively. The presented method has been successfully used for the determination of DA in commercial preparation and human urine samples after clean-up using SPE.