4th Exam Spectroscopic Methods for Biological Molecules Flashcards
The Electromagnetic spectrum order from high energy, high frequency, short wavelength to low, long freq
X-ray
Ultraviolet (200 nm)
Visible
Infrared
Microwave
Radio
Nuclear magnetic resonance
has many different applications in organic and biological chemistry.
UV-Vis Spectroscopy
used to determine the concentration of a CHROMOPHORE
- one of the application of the UV-Vis spectroscopy
Beer-Lambert Law
law that is simply an application of the observation that, within certain ranges, the absorbance of a chromophore at a given wavelength varies in a linear fashion with its concentration: the higher the concentration of the molecule, the greater its absorbance.
Beer-Lambert Law
Beer-Lambert Law formula
A = εbc
A = -log T
T = I/I0
Spectrophotometric determination of organic compounds containing one or more of these groups is thus potentially feasible
Absorbing Species
T OR F
Only organic species can be absorbed.
False
A number of inorganic species also absorb. Many ions of the transition metals are colored in solution and can thus be determined by spectrophotometric measurement.
A number of other inorganic species show
characteristic absorption bands, including
nitrite, nitrate, and chromate ions, the oxides of nitrogen, the elemental halogens, and ozone.
non-absorbing analytes can be determined photometrically by causing them to react with___________ to produce products that absorb strongly in the ultraviolet and visible regions
chromophoric reagents / color -forming reagents
The successful application of these usually requires that their reaction with the analyte be forced to near completion unless methods such as kinetic methods. Typical inorganic reagents include the following:
▪ thiocyanate ion for iron, cobalt, and molybdenum;
▪ hydrogen peroxide for titanium, vanadium, and chromium;
▪ iodide ion for bismuth, palladium, and tellurium.
