Dr. W.T. Chan

Metal speciation using capillary electrophoresis (CE) – ICP spectrometry: The project involves development of novel CE-ICP interfaces and method development for metal speciation. CE-ICP interfaces using concentric and cross flow nebulization have been developed. We have also developed a continuous-flow field-amplified sample stacking technique for chip-based CE for on-line analyte ion preconcentration and a microwave plasma treatment method for irreversible sealing of poly(dimethylsiloxane) (PDMS) chips using a microwave oven.
Spatial-preconcentration of trace metal for ICP-MS measurement: We have developed a preconcentration method using nano-particles of iron hydroxide and carbon nanotubes. Analyte metal ions are adsorbed onto the nano-particles and the mixture is introduced into the ICP by conventional nebulization method. The number density of the analyte ions in the ICP at the vicinity of the nano-particle is larger than that of the original sample solution. Analyte ions on each particle produce an ICP-MS current spike. Time-resolved measurement of the current spikes improves the ICP-MS detection limits by an order of magnitude or more.
Bottom-view ICP-AES spectrometry: We have developed a method to measure ICP emission via the bottom of the ICP torch. A conventional radial-viewing ICP can be readily adapted to bottom-viewing. Similar enhancement in sensitivity as the axial-viewing ICP was observed: signal-to-background ratio (SBR) was increased by 5 times or more for atomic lines and 2-4 times for ionic lines.
Direct sample insertion (DSI) for ICP-AES: The project involves development of novel DSI probes for one-step analyte preconcentration / matrix separation and fundamental studies of the effects of probe insertion on the excitation conditions of the ICP using conventional solid sample probe and hollow sample probe.

Dr. W.T. Chan　　　陳榮達博士 B.Sc. C.U.H.K.; Ph.D. Alberta


Office:			Room 305 Chong Yuet Ming Chemistry Building The University of Hong Kong Pokfulam Road Hong Kong
Office:				Tel. No.: E-Mail:	(852) 2859 2156 wtchan@hku.hk

	Research Interest

		Research interests are in the area of analytical spectroscopy and metal speciation, with emphasis on the development and application of atomic spectrochemical measurement systems. Current research projects include spatial preconcentration of trace metal for inductively coupled plasma-mass spectrometry (ICP-MS) measurement, tandem technique of capillary electrophoresis (CE)-ICP, bottom-view ICP-atomic emission spectrometry, and direct sample insertion (DSI) for ICP. Current Projects: Metal speciation using capillary electrophoresis (CE) – ICP spectrometry: The project involves development of novel CE-ICP interfaces and method development for metal speciation. CE-ICP interfaces using concentric and cross flow nebulization have been developed. We have also developed a continuous-flow field-amplified sample stacking technique for chip-based CE for on-line analyte ion preconcentration and a microwave plasma treatment method for irreversible sealing of poly(dimethylsiloxane) (PDMS) chips using a microwave oven. Spatial-preconcentration of trace metal for ICP-MS measurement: We have developed a preconcentration method using nano-particles of iron hydroxide and carbon nanotubes. Analyte metal ions are adsorbed onto the nano-particles and the mixture is introduced into the ICP by conventional nebulization method. The number density of the analyte ions in the ICP at the vicinity of the nano-particle is larger than that of the original sample solution. Analyte ions on each particle produce an ICP-MS current spike. Time-resolved measurement of the current spikes improves the ICP-MS detection limits by an order of magnitude or more. Bottom-view ICP-AES spectrometry: We have developed a method to measure ICP emission via the bottom of the ICP torch. A conventional radial-viewing ICP can be readily adapted to bottom-viewing. Similar enhancement in sensitivity as the axial-viewing ICP was observed: signal-to-background ratio (SBR) was increased by 5 times or more for atomic lines and 2-4 times for ionic lines. Direct sample insertion (DSI) for ICP-AES: The project involves development of novel DSI probes for one-step analyte preconcentration / matrix separation and fundamental studies of the effects of probe insertion on the excitation conditions of the ICP using conventional solid sample probe and hollow sample probe.
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	Selected Publications

		K.K.K. Lam, W.T. Chan, J. Analyt. At. Spect., 1997, 12, 7-12. W.T. Chan, H.H.C. Yip, Anal. Chem., 1997, 69, 4872-4877. G.C.Y. Chan, W.T. Chan, J. Anal. Atom. Spectrom., 1998, 13, 209-214. Y.Y. Chan, W.T. Chan, J. Chrom. A , 1999, 853, 141-149. B. Deng, W.T. Chan, J. Chrom. A, 2000, 891, 139-148. G.C.Y. Chan, W.T. Chan, Spectrochim. Acta Part B, 2002, 57, 1771-1787. G.C.Y. Chan, W.T. Chan, Spectrochim. Acta Part B, 2003, 58, 1301-1317. A.W.K. Cheung, W.T. Chan, J. Anal. At. Spectrom., 2004, 19, 1111-1118. A.Y.N. Hui, G. Wang, B. Lin, W.T. Chan, Lab. Chip., 2005, 5, 1173-1177. M.H.P. Yau, W.T. Chan, J. Anal. At. Spectrom., 2005, 20, 1197-1202.
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