1. 5.4 Notes

2. Objectives
Describe the utility of ultraviolet and infrared spectroscopy for the identification of organic compounds
Describe the concept and utility of mass spectrometry for identification analysis

3. Beer’s Law
The relationship exists between absorption and concentration
A = kc
Where A is the absorption or quantity of light, c is the concentration of the absorbing material and k is a proportionality constant

4. FT-IR
Fourier transport infrared spectrometer using a Michelson interferometer
The current laboratory approach.
It uses a prism and two mirrors to direct light to a sample
As light passes through the sample it is detected by an instrument that measures all wavelengths simultaneously
Then uses a mathematical operation (FT) to decode the signals and record the wavelength.

5. FT-IR It is calculated by a computer and prepares a printout.
Samples have been dissolved in a solvent.
Glass cells used to measure the visible region
Quartz to measure the UV region
Sodium chloride or potassium bromide used to measure the rest

6. UV & Visible Spectrophotometry
measures the absorbance of UV and visible light based on wavelength or frequency.
Heroin has a wavelength of 278 nm.
Sugar and starch are often the dilutants for heroin and do not absorb UV light.

7. Absorption in IR Region
is more specific and can be the equivalent of a fingerprint based on the spectra.
Thousands of organic compounds have been indexed and catalogued.

8. GC-Mass Spec
Use of gas chromatography and mass spectrometry can now be used identify specifically
Substance is passed through a GC then flows into a Mass Spec
Material is ionized and decomposes
Smaller fragments are separated by their masses
NO TWO SUBSTANCES PRODUCE THE SAME FRAGMENTED PATTERN.

9. In-Class Assignment/Homework