CEC with tris (2,2′-bipyridyl) ruthenium (II) electrochemiluminescent detection

For the first time, CEC was coupled with tris(2,2-bipyridyl) ruthenium(II) (Ru(bpy)₃²⁺ electrochemiluminescence detection. Efficient CEC separations of proline, putrescine, spermidine and spermine were achieved when the pH of the mobile phase is in the range of 3.5-7.0. The optimum mobile phase for CEC separation is much less acidic than that for CZE separation, which matches better with the optimum pH for Ru(bpy)₃²⁺ electrochemiluminescence detection and dramatically shortens the analysis time because of larger EOF at higher pH. The time for CEC separation of the polyamines is less than 12.5 min, which is about half as much as the time needed for CZE. The detection limits were 1.7, 0.2, and 0.2 μM for putrescine, spermidine, and spermine, respectively. The RSD of retention time and peak height of these polyamines were less than 0.85 and 6.1%, respectively. The column showed good long-term stability, and the RSD of retention time is below 5% for 150 runs over one-month use. The method was successfully used for the determination of polyamines in urine samples.