ICP (NOT MS)

Question 1

How Does ICP-OES work?

Answer 1

Uses an INDUCTIVELY COUPLED PLASMA SOURCE to dissociate sample into constituent atoms or ions. This excites them to a level where they emit light at a characteristic wavelength. Detector measures intensity of emitted light.

Question 2

Basic Schematic of ICP-OES

Answer 2

Sample introduced -> Plasma -> Monochromator -> Detector

Question 3

Strengths and Weaknesses of ICP-OES

Answer 3

Strengths:
Multi-element
Few chemical interferences
Excellent screening
Solid and organic samples
high total dissolved solids
very economical for lots of samples

Weaknesses:
Moderate to low detection limits
Spectral interferences possible
Some element limitations

Question 4

How is the ICP Plasma formed?

Answer 4

Gas (usually Ar) significantly ionised inside oscillating radio frequency field with tangential coolant flow to stop melting

Question 5

What are the two types of Plasma Mode?

Answer 5

Radial (90 degrees from axis of ICP) and Axial (same axis as ICP)

Question 6

Advantages and disadvantages of Radial and Axial?

Answer 6

RADIAL
Strengths:
excellent LOD and reduced interferences

Axial
Strengths:
High sensitivity
Weaknesses:
More interference than radial view.

Question 7

More advanced schematic of ICP-OES?

Answer 7

Sample -> pump -> Nebulizer -> ICP Torch -> Spectrometer -> Detector -> Data processor

Question 8

Overall strengths and weaknesses of ICP-OES?

Answer 8

Strengths:
Low detection limits
large linear dynamic range
few chemical interferences

Weaknesses:
Interferences because of easily ionizable elements
Spectroscopic interferences
Sample transport effects