Studies of tris(2,2'-bipyridyl)ruthenium(II) electrogenerated chemiluminescence for detection in flowing streams
This research has involved the characterization and application of tris(2,2$\sp\prime$-bipyridyl)ruthenium(II) (Ru(bpy)$\sb3\sp{2+}$) electrogenerated chemiluminescence (ECL) for detection in flowing streams. Three approaches were comparatively evaluated for use of Ru(bpy)$\sb3\sp{2+}$ as a chemiluminescent reagent in flowing streams. The three approaches evaluated are external generation of the Ru(bpy)$\sb3\sp{3+}$ followed by contact with analyte, in-situ generation of the Ru(bpy)$\sb3\sp{3+}$ on the electrode surface from the solution phase Ru(bpy)$\sb3\sp{2+}$, and in-situ generation of the Ru(bpy)$\sb3\sp{3+}$ from the Ru(bpy)$\sb3\sp{2+}$ immobilized within the observation cell. The external generation mode yields the most intense emission but working curves have poor linearity and emission intensities have large dependence on solution flow rate. The in-situ/solution mode is superior for the detection of amino acids and has time, convenience, and reliability advantages. The in-situ/immobilized mode results in lower intensities, but yields the widest linear dynamic ranges, and is most conservative of reagent. Ru(bpy)$\sb3\sp{2+}$ ECL was employed for the determination of dansyl amino acids in HPLC. The Ru(bpy)$\sb3\sp{2+}$ can be added to post-column effluent via a mixing-tee or the Ru(bpy)$\sb3\sp{2+}$ can be directly placed in the mobile phase. In the latter approach, the pump, tubing, and mixer necessary for post-column addition are eliminated although the retention times change. The effect of organic solvents on Ru(bpy)$\sb3\sp{2+}$ CL was characterized with oxalate and proline as model analytes. As acetonitrile, methanol, and acetone percentages increase, the ECL intensities also increase. This leads to enhanced sensitivity, but would also lead to variation in sensitivity with retention times for separations done by gradient elution. Use of 2-propanol, in contrast, led to ECL of reduced intensity, but more constant with composition. Preliminary work on the effect of flow rate, spacer thickness, and linear velocity on Ru(bpy)$\sb3\sp{2+}$ ECL was performed in the in-situ/solution mode. Also, preliminary planning and work involving Ru(bpy)$\sb3\sp{2+}$ ECL detection in CE were performed.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign