Thesis (M.Sc.)--Chulalongkorn University, 2012

Graphene (G) – a two dimensional sheet of sp2 carbon atom, has become an attractive materials in electrochemistry due to its high electrical conductivity, high mechanical strength and potentially low manufacturing cost. In this study, the nanocomposite of G and polyaniline (PANI) was prepared and was successfully modified on screen-printed carbon electrode by electrospraying technique. The G/PANI-modified electrode was compared with bare carbon and boron-doped diamond electrode and then applied for simultaneous determination of eight sulfonamides (SAs) using ultra fast liquid chromatography (UFLC). UFLC coupled with amperometric detection on G/PANI modified electrode offered high sensitivity and fast response with separation for all eight SAs within 7 minutes by using 70:25:5 (v/v/v) of potassium hydrogen phosphate solution (pH 3): acetonitrile: ethanol as mobile phase. Amperometric detection was performed at a detection potential of +1.4 V. The linearity of this system was obtained in a range of 0.01-10 µg mL-1with a 0.99 correlation coefficient, and the limit of detection was found in a range of 1.162-6.127 ng mL-1 for all SAs. Overall, this novel system provides high sensitivity and rapid analysis for selective determination of eight SAs.