UV-Vis Spectroscopy http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy/UV-Vis/spectrum.htm

HPLC: Peak Area vs Detector setting UV-Vis Spectroscopy HPLC: Peak Area vs Detector setting Excedrin ES 250 mg aspirin; 250 mg acetaminophen; 65 mg caffeine Detector set at 240 nm Area % Aspirin 19.5% Acetaminophen 50.0% Caffeine 20.5% Detector set at 254 nm Area % Aspirin 7.3% Acetaminophen 81.9% Caffeine 10.8% Detector set at 280 nm Area % Aspirin 24.8% Acetaminophen 39.3% Caffeine 35.9%

UV-Vis Spectroscopy: lmax 240 nm Acetaminophen (1.6 x 10-3 g/L) lmax = 248 nm, Abs. = 0.61 254 nm 280 nm Aspirin (1.6 x 10-3 g/L) lmax = 296 nm, Abs. = 0.18 Caffeine (1.6 x 10-3 g/L) lmax = 272 nm, Abs. = 0.34

UV-Vis Spectroscopy: lmax and molar absorbtivity (e) Acetaminophen (1.6 x 10-3 g/L) lmax = 248 nm, Abs. = 0.61 Caffeine (1.6 x 10-3 g/L) lmax = 272 nm, Abs. = 0.34

UV-Vis Spectroscopy: Chromophores http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy /UV-Vis/spectrum.htm

Methyl bromide Methyl Iodide UV-Vis: Chromophores Chromo-phore Example Excitation λmax, nm ε Solvent C=C Ethene π  __>   π* 171 15,000 hexane C≡C 1-Hexyne 180 10,000 C=O Ethanal n  __>  π* π  __>  π* 290 180 15 10,000 hexane hexane N=O Nitro-methane 275 200 17 5,000 ethanol ethanol C-X   X=Br X=I Methyl bromide Methyl Iodide n  __>  σ* n  __>  σ* 205 255 200 360 http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy/UV-Vis/spectrum.htm

UV-Vis Spectroscopy: Chromophores Table 7.3, p 362 Intro to Spectroscopy, 3rd ed., Pavia et al.

UV-Vis Spectroscopy: Solvents p 358-9 Intro to Spectroscopy, 3rd ed., Pavia et al.

UV-Vis Spectroscopy: CONJUGATION p 363 Intro to Spectroscopy, 3rd ed., Pavia et al. http://www.cem.msu.edu/~reusch/VirtualText/ Spectrpy/UV-Vis/spectrum.htm

UV-Vis Spectroscopy: Aromatic Compounds p 375-76 Intro to Spectroscopy, 3rd ed., Pavia et al.

UV-Vis: Aromatics p 379 Intro to Spectroscopy, 3rd ed., Pavia et al.

UV-Vis: Acid/Base p 377 Intro to Spectroscopy, 3rd ed., Pavia et al.

UV-Vis: Acid/Base Terminology for Absorption Shifts Nature of Shift Descriptive Term To Longer Wavelength Bathochromic To Shorter Wavelength Hypsochromic To Greater Absorbance Hyperchromic To Lower Absorbance Hypochromic

UV-Vis: Acid/Base

UV-Vis: Empirical Rules   p 380 Intro to Spectroscopy, 3rd ed., Pavia et al.

UV-Vis: Empirical Rules   p 380 Intro to Spectroscopy, 3rd ed., Pavia et al.