Simultaneous Determination of Five Bioactive Constituents in Rhizoma Chuanxiong by Capillary Electrophoresis with a Carbon Nanotube-polydimethylsiloxane Composite Electrode

A carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite electrode was developed for the capillary electrophoretic determination of the bioactive constituents in Rhizoma Chuanxiong, a traditional Chinese medicine. The novel composite electrode was fabricated on the basis of the in situ polyaddition of curing agent-containing dimethyl siloxane oligomer in the presence of CNTs in the inner bore of a piece of fused silica capillary under heat. It was coupled with capillary electrophoresis for the separation and detection of vanillin, ferulic acid, vanillic acid, caffeic acid, and protocatechuic acid in Rhizoma Chuanxiong to demonstrate its feasibility and performance. The five phenolic constituents were well separated within 13min in a 45cm long capillary at a separation voltage of 15kV using a 50mM borate buffer (pH 9.2). The CNT-based detector offered higher sensitivity, significantly lower operating potential, satisfactory reproducibility, and lower expense of operation, indicating great promise for a wide range of analytical applications.