Capillary Electrophoresis of Polyamines with Universal Indirect Chemiluminescence Detection, Using Cobalt (II) as a Probe Ion

Abstract

Highly sensitive indirect chemiluminescence detection for capillary electrophoresis (CE) of polyamines was demonstrated in this paper. In the indirect chemiluminescence (CL) detection system, a strong and stable background CL signal can be generated by the luminol‐hydrogen peroxide reaction catalyzed by cobalt (II) probe ion in the running buffer. Displacement of the cobalt (II) probe ion in the running buffer, by migrating polyamine cations, results in a decrease in the background signal. Some factors affecting the separation of polyamines, such as buffer pH, buffer concentration, and additives, were systematically investigated using a commercial CE instrument with an in‐house‐built CL detector. Under the optimal conditions, three polyamines, putrescine (PUT), spermidine (SPD), and spermine (SPM) were well separated in less than 4.5 min. The detection limits of the concentration for PUT, SPD, and SPM were 1.0 × 10⁻⁸, 5 × 10⁻⁹, and 1.2 × 10⁻⁸ mol/L (S/N = 3), respectively. This sensitivity is about three orders better than that in the UV detection, and is almost the same as in the laser induced fluorescence detection. Our data further demonstrated that CE with indirect CL detection was a powerful tool for analysis of organic cations.

Keywords:

• Capillary electrophoresis
• Indirect luminescence
• Probe ion