Flow Injection Analysis of Kojic Acid in Cosmetics by a Carbon-Nanotube Modified Screen-Printed Electrode
YING SHIH1*, JYH-MYNG ZEN2, JYH-HARNG KE2, JAW-CHERNG HSU1 AND PEI-CHI CHEN1
1.Department of Applied Cosmetology, Hung Kuang University, Taichung 433, Taiwan, R.O.C.
2.Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan, R.O.C.
(Received: October 11, 2006; Accepted: January 12, 2007)
Abstract
A novel carbon-nanotube modified screen-printed electrode (CNT/SPE) was successfully prepared and validated to be a useful detector in the flow injection system. Compared to a bare screen-printed electrode (SPE), CNT/SPE improved the detection limit for kojic acid (KA). The detection limit on S/N = 3 was as low as 0.01 ppm. Furthermore, several factors, including the pH, applied potential, flow rate and coating quantity of CNT, were assessed. The attractive response of CNT/SPE has allowed it to be used for constant-potential FIA (Flow-Injection Analysis) of KA and indicates great potential for monitoring chromatographic effluents. The linear relationship between KA concentration (0.1-120 ppm) and the current response was established. Meanwhile five different CNT/SPEs for the detection KA of 20 ppm yielded a RSD value of 4.43%, indicating acceptable reproducibility of the present analysis. Finally, two real samples on the market were analyzed using the proposed system with appreciable results.
Key words: carbon nanotubes, screen-printed electrode, kojic acid, flow injection analysis, cosmetics