Surfactant-coated graphitized multiwalled carbon nanotubes as the pseudostationary phase in electrokinetic chromatography for the analysis of phytochemical compounds in biological fluids.

This report describes the use of surfactant-coated graphitized multiwalled carbon nanotubes (SC-GMWNTs) as a novel pseudostationary phase in CE with diode array detection for the determination of phenolic acids and tanshinones in herbal and urine samples. Several parameters influencing the separation were studied, such as the concentrations of SDS, GMWNTs, and isopropanol; choice of carbon nanotubes; sodium borate content; and buffer pH. The results revealed that the presence of SC-GMWNTs in buffer enhanced the separation efficiency for the target analytes relative to conventional micelles due to the strong interaction between the surface of the GMWNTs and the target compounds. Under the optimum conditions, the method showed good linearity, with correlation coefficients higher than 0.9950. LODs were in the range of 0.71-3.10 μg/mL. Furthermore, satisfactory separations were achieved with good recovery values in the range of 89.97 and 103.30% when 10 mM borate, 30 mM SDS, 10% isopropanol, and 6 μg/mL SC-GMWNTs were introduced into the buffer solution.