A new approach for the detection of a nonfluorescent compound by CE-resonance Raman spectroscopy based on the sweeping-MEKC mode

• Published in: Electrophoresis 2006-12, Vol.27 (23), p.4688-4693
• Main Authors: Tsai, Chih-Hsin, Chan, Po-Han, Lin, Cheng-Huang, Chang, Ta-Chau, Chia, Chih-Ta
• Format: Article
• Language: English
• Subjects: Chromatography, Micellar Electrokinetic Capillary - methods; Colloids - chemistry; Coloring Agents - analysis; Electrophoresis, Capillary - methods; Lasers; Malachite green; Raman spectroscopy; Rosaniline Dyes - analysis; Silver - chemistry; Spectrum Analysis, Raman - methods; Surface enhanced-resonance Raman spectroscopy; Sweeping-MEKC
• ISSN: 0173-0835; 1522-2683
• DOI: 10.1002/elps.200600393

A CE‐resonance Raman spectroscopy (CE‐RRS) method based on MEKC and sweeping‐MEKC modes is described. A nonfluorescent compound, malachite green (MG), and a doubled Nd:YAG laser (532 nm, 300 mW) were selected as model compound and light source, respectively. In order to carry out a quantitative analysis of MG, a monochromator (effective bandwidth, 0.4 nm) was used to collect the specific Raman line at 1616 cm−1 (N‐ϕ and C–C stretch, corresponding to 582 nm when the wavelength of the exciting source was 532 nm). As a result, the LOD for MG was 10 ppm, based on the MEKC/RRS mode. This could be improved to 5 ppb when the sweeping‐MEKC/RRS mode was applied. Furthermore, with the addition of nano‐size silver colloids to the CE buffer the detection limits can be further improved, but the data obtained with surface‐enhanced resonance Raman spectroscopy (SERRS) are less useful for quantitative purposes.