1. Lecture 19 Spectrophotometry- III

2. Light Source Sample Monochromator (filter, wavelength selector) Detector Spectrometer Data Processing

3. Single beam Double beam

4. A tungsten lamp 3000 K

5. Deuterium Lamp Deuterium: higher intensity UV sources

6. Limits to Beer’s Law Incident light P0P0 Emergent light P1P1 Stray light

8. Solvents for UV/vis Spectrophotometry Solvent Lower Wavelength Limit Water180 nm Ethanol 220 nm Hexane and200 nm Cyclohexane Acetone320 nm

10. Beer’s law Bugert, Lambert and Beer A concentration Straight line!

11. Wavelength, nm A or  B Other components of the mixture Measure @ this wavelength!

12. Limits to Beer’s Law Polychromatic light (several wavelength)

13. Wavelength, nm A or  B Other components of the mixture Intensity is too low!

14. Wavelength, nm A or  B Other components of the mixture Measurement is difficult

15. Wavelength, nm A or  C Other components of the mixture Measure @ this wavelength! B + reagent  C Compound is chemically derivitized (transformed) prior to the measurement of absorbance

16. Cu 2+ Hg 2+