The key role of copper complexes adsorbed on a chemically endcapped diamine bonded phase for HPLC

Chromatographic silica (10 mum) was chemically modified with the organosila ne [3-(2-aminoethyl)aminopropyl]trimethoxysilane (AEAPTS) and further endca pped with trimethylchlorosilane (TMCS). Copper ions were complexed onto the modified silica surface through pendant amine groups. The purpose of the i mmobilized copper complexes is to provide new sites in the stationary phase that can interact strongly with basic organic compounds. A conventional te st mixture composed of dipolar compounds such as benzene, toluene, naphthal ene, anthracene, pyrene, and nitrobenzene was used to evaluate these new co lumns. A second mixture, composed of aromatic amines, N,N-diethylaniline, a nd aniline, was chosen to evaluate the effects caused by complexation of co pper ions on the modified silica.