Chapter 20 - Atomic Spectroscopy

Question 0

What are some applications of atomic spectroscopy?

Answer 0

• forensics (toxicological)
• biological (metal speciation)
• environmental (water hardness)
• manufacturing (chemical purity)

Question 1

At what temperature are samples vaporized in atomic spectroscopy?

Answer 1

Samples are vaporized at 2000 K - 8000 K and decomposed into atoms.

Question 2

How does flame atomization work?

Answer 2

Sample solution is drawn into the pneumatic nebulizer by the rapid flow of oxidant past the tip of the sample capillary. Liquid breaks into fine mist as it leaves the capillary. The spray is directed against a glass bead, upon which the droplets break into smaller particles. The nebulizer creates an aerosol from the liquid sample. The mist, oxidant, and fuel flow past the baffles that promote further mixing and block large droplets of liquid. Excess liquid collects at the bottom of the spray chamber and flows out the drain.

Question 3

Which is a hotter flame, fuel “lean” or fuel “rich”?

Answer 3

Fuel “lean” flames are hotter.

Question 4

Which is more sensitive, flame atomization or furnace atomization?

Answer 4

Furnace atomization is more sensitive because it has longer residence times and requires less sample.

Question 5

What is a matrix modifier?

Answer 5

A matrix modifier is a substance added to a sample to reduce the loss of analyte during charring by making the matrix more volatile or the analyte less volatile.

Question 6

Why are inductively coupled plasma a more sensitive method of atomization?

Answer 6

Inductively coupled plasmas are about 2x as hot as a combustion flame reaching up to 10,000 K. This high temperature:

• eliminates interfering molecules
• allows more complete atomization
• does not lead to metal oxides or hydroxides
• reduces background radiation