1 / 13

UV-vis

UV-vis. Applications. Quantitative analysis Organics (if composition is simple and known) Specific binding to chromaphore Metal-ligand absorption (d-orbital splitting), (Co2+ experiment in gen chm). cuvette. slit. source. detector. Beer’s Law. A = -logT = log(P 0 /P) = e bc

ban
Download Presentation

UV-vis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. UV-vis

  2. Applications • Quantitative analysis • Organics (if composition is simple and known) • Specific binding to chromaphore • Metal-ligand absorption (d-orbital splitting), (Co2+ experiment in gen chm)

  3. cuvette slit source detector Beer’s Law • A = -logT = log(P0/P) = ebc • T = Psolution/Psolvent = P/P0 • Works for monochromatic light • Compound x has a unique e at different wavelengths

  4. Beer’s Law Analysis • Choice of wavelength • Typically choose wavelength of maximum absorbance • May deviate from this to avoid an interference

  5. Common UV-vis instuments Scanning Instrument monochromator slit Tungsten Filament (vis) Photomultiplier tube slit cuvette Deuterium lamp Filament (UV)

  6. sources • Tungten lamp (350-2500 nm) • Deuterium (200-400 nm) • Xenon Arc lamps (200-1000 nm)

  7. Monochromator • Braggs law, nl = d(sin i + sin r) • Angular dispersion, dr/dl = n / d(cos r) • Resolution, R = l/Dl = nN, resolution is extended by concave mirrors to refocus the divergent beam at the exit slit

  8. Sample holder • Visible; can be plastic or glass • UV; you must use quartz

  9. Single beam vs. double beam • Source flicker

  10. Diode array Instrument mirror Diode array detector 328 individual detectors Tungsten Filament (vis) slit slit cuvette Deuterium lamp Filament (UV) monochromator

  11. Advantages/disadvantages • Scanning instrument • High spectral resolution (63000), l/Dl • Long data acquisition time (several minutes) • Low throughput • Diode array • Fast acquisition time (a couple of seconds), compatible with on-line separations • High throughput (no slits) • Low resolution (2 nm)

  12. HPLC-UV HPLC Pump HPLC column 6-port valve Mobile phase Sample loop UV detector syringe Solvent waste

More Related