Thesis (M.Sc.)--Chulalongkorn University, 2009

In this research, a method for the simultaneous determination of Pb (II), Cd (II), and Zn (II) at low mug L[superscript -1] concentration levels by sequential injection analysis-anodic stripping voltammetry (SIA-ASV) using screen-printed carbon nanotube electrode (SPCNTE) was developed. A bismuth film was prepared by in situ plating of bismuth on the screen-printed carbon nanotubes electrode. Operational parameters such as ratio of carbon nanotubes to carbon ink, bismuth concentration, deposition time and flow rate during preconcentration step were optimized. Under the optimal conditions, the linear ranges were found to be 2-100 L[superscript -1]for Pb (II) and Cd (II), and 12-100 L[superscript -1]for Zn (II). The limits of detection (Sbl/S=3) were 0.2 μg L-1 for Pb (II), 0.8 L[superscript -1]for Cd (II) and 11 L[superscript -1]for Zn (II). The measurement frequency was found to be 10-15 stripping cycle h-1. The present method offers high sensitivity and high throughput for on-line monitoring of trace heavy metals. The practical utility of our method was also demonstrated with the determination of Pb (II), Cd (II), and Zn (II) by spiking procedure in herb samples.