Effects of aliphatic amines on capillary electrochromatographic performance of tricyclic antidepressants on octadecylsilica

Adding aliphatic amines to the mobile phase improves peak symmetry and effi ciency in capillary electrochromatography of tricyclic antidepressants on o ctadecylsilica. The most hydrophobic aliphatic amine studied, dimethyloctyl amine (DMOA), was the most efficient. Despite the fact that the amine addit ives substantially reduced the electroosmotic flow, the retention of the an alytes decreased indicating a strong competitive effect of the additives. D MOA gave the largest retention decrease, and simultaneously reduced the res olution, indicating that silanophilic interaction is significant to the sep aration. Highest efficiencies were obtained at the lowest pH (2.8). Acetoni trile influenced both efficiency and peak symmetry, and best results were o btained at 60%. (C) 2000 Elsevier Science B.V. All rights reserved.