1. ATOMIC ABSORPTION AND ATOMIC FLUORESCENCE SPECTROMETRY Chap 9

2. Absorption and fluorescence by atoms in a flame.

3. ATOMIC ABSORPTION AND ATOMIC FLUORESCENCE SPECTROMETRY Chap 9 Atomization Flame Flame Electrothermal (“furnace”) Electrothermal (“furnace”)

4. SAMPLE INTRODUCTION METHODS Common Types of Atomizers (from SHN, 5e, Table 8-1) Flame1700 – 3100 °C Flame1700 – 3100 °C Electrothermal (“furnace”)1200 – 3000 °C Electrothermal (“furnace”)1200 – 3000 °C Inductively coupled plasma (ICP)4000 – 6000 °C Inductively coupled plasma (ICP)4000 – 6000 °C Electric arc 4000 – 5000 °C Electric arc 4000 – 5000 °C (e.g., Vreeland spectroscope)

5. Table 9-1 Properties of Flames

6. Regions in a Flame Fig. 9-2 (most useful)

7. Temperature profiles for a natural gas - air flame Fig. 9-3

8. Laminar Flow Burner Fig 9-5 Advantages: quiet flame quiet flame long path length long path length (usually 10 cm) (usually 10 cm) superior superior reproducibility reproducibility compared to all compared to all other methods other methods Disadvantages: poor efficiency poor efficiency short residence time short residence time hv source

9.  Flame Atomization Laminar flow burner head hνhνhνhν Fig. 9-13 (a) ( acetylene) 2100 -2400 °C

10. Electrothermal Atomization Electrothermal Atomization (graphite furnace) Fig. 9-6 (a) Advantages: highly sensitive down highly sensitive down to pg of analyte to pg of analyte long residence time long residence time more efficient than more efficient than flame flame use with solid samples use with solid samples Disadvantages: poor reproducibility poor reproducibility small analytical range small analytical range h ν in h ν out

11. The L’vov platform Fig. 9-6 (b)

12. Graphite tube hv sourcedetector Graphite Furnace

13. Correct position for injecting sample into graphite furnace sample into graphite furnace If injection is too high, sample splatters and precision is poor

14. Heating profiles comparing analyte vaporization from walls and from platform (note constant T) not reliablereliable

15. Atomic Absorption Instrumentation The Source

16. Atomic Absorption Instrumentation Hollow-Cathode Lamp Hollow-Cathode Lamp Fig. 9-11 Ne or Ar at 1 – 5 torr Atoms sputter off cathode 300 V at 5 – 15 mA

17. Typical output from an Fe HCL

18. Atomic Absorption Instrumentation Electrodeless Discharge Lamp Electrodeless Discharge Lamp Fig. 9-12 Higher intensity than HCL Higher intensity than HCL Performance less reliable Performance less reliable EDL

19. Typical Flame Spectrophotometer Fig. 9-13 (b) Double-beam