Circular dichroism thermal lens microscope in the UV wavelength region (UV-CD-TLM) for chiral analysis on a microchip |
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Authors: | Kazuma Mawatari Shun Kubota Takehiko Kitamori |
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Affiliation: | (1) Microchemical Group, Kanagawa Academy of Science and Technology, 3-2-1 Sakado, Takatsu, Kawasaki Kanagawa, 213-0012, Japan;(2) Department of Applied Chemistry, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan |
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Abstract: | We have developed a circular-dichroism thermal lens microscope for UV wavelengths (UV-CD-TLM), for the first time, to realize sensitive chiral analysis on a microchip. Quasi-continuous-wave phase modulation of a pulsed UV laser was used to generate left-circularly polarized light and right-circularly polarized light and to detect the generated TL signal amplitude and phase with a lock-in amplifier. The amplitude and phase were used to determine the concentration and chirality, respectively, of a sample. The basic principle of UV-CD-TLM for chiral analysis on a microchip was verified by measuring aqueous solutions of optically active camphorsulfonic acids (CSA). Lower limits of detection (LOD) were calculated at S/N = 2 and were 8.7 × 10−4 mol L−1 (ΔA = 5.2 × 10−6 Abs.) for (+)-CSA and 8.4 × 10−4 mol L−1 (ΔA = 5.0 × 10−6 Abs.) for (−)-CSA. In terms of number of molecules, LODs for UV-CD-TLM were calculated to be 8.7 fmol and 8.4 fmol, respectively. This is at least three orders of magnitude lower than previously obtained. The applicability of UV-CD-TLM for chiral analysis on a microchip was verified. Figure Sensitive chiral analysis by thermal lens microscope (TLM) |
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Keywords: | Thermal lens microscope Circular dichroism effect Nonfluorescent molecules Microchip Chiral analysis |
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