Analytical Chemistry-ICP Mass Spectrometry

1. Module 18
INDUCTIVELY COUPLED PLASMA -
MASS SPECTROMETRY
AND FLAME EMISSION
SPECTROMETRY

2. Contents:
1. Overview / Principle
2. Mechanism / Instrumentation
3. Strengths / Limitations
4. Applications

3. 1. Overview / Principle

4. 1. Overview / Principle
❏ Inductively coupled plasma mass spectrometry is a type of mass
spectrometry which is capable of detecting metals at very low
concentrations.
❏ ICP-MS can detect about 80 elements with ppb and ppt levels with
liquid samples.
❏ Used for qualitative analysis, isotope ratio, semi-quantitative analysis
and quantitative analysis.

5. 2. Mechanism / Instrumentation

6. 2. Mechanism / Instrumentation
● ICP-MS combines a high temperature ICP source
with a mass spectrometer.
● The ICP source converts the atoms of the elements
in the sample to ions.
● These ions are then separated and detected by the
mass spectrometer.

7. 2. Mechanism / Instrumentation
● ICP is a plasma that is ionized by inductively heating
the gas with an electromagnetic coil.
● Argon (Ar) gas is electrically heated to a high
temperature (>6000 K) plasma.

8. 2. Mechanism / Instrumentation
The ions enter to an
electric field and are
separated according
to their mass/charge
(m/z) ratio.
The signal intensities
are directly
proportional to the
concentrations of the
elements in the
sample.

9. 2. Mechanism / Instrumentation
A. Sample Preparation

10. 2. Mechanism / Instrumentation
A. Sample Preparation
B. ICP Torch with Nebulizer
*ICP Torch: consists of a triple tube w/ a concentric circle made of
quartz.
A. Ion extraction from plasma
B. Quadrupole mass analyzer: Mass separation

11. 2. Mechanism / Instrumentation
E. Ion detection

12. 3. Strengths and Limitations
❏ Strengths:
❏ Fast: 30 elements for 1 minute
❏ Has low detection limit: 1-100 pg/mL
❏ Simple mass spectrum: qualitative analysis for each isotopes.
❏ Measure the isotopic ratio of an element.

13. 3. Strengths and Limitations
❏ Limitations:
❏ Total dissolved solids (TDS) <0.1-0.2 %
❏ Only small fraction of samples are introduced into the plasma.
❏ Polyatomic interference
❏ Isobaric interference
❏ Matrix interference

16. 4. Applications
❏

17. 4. Applications

18. 4. Applications

19. 4. Applications
Inductively Coupled Plasma Mass Spectrometry is becoming more
widely used in the analysis of trace metals because of its sensitivity,
wide range of elements covered, and relative freedom from
interferences. It is an elemental analysis technology capable of detecting
most of the periodic table of elements at milligram to nanogram levels per
liter. It is used in a variety of industries including, but not limited to,
environmental monitoring, geochemical analysis, metallurgy,
pharmaceutical analysis, and clinical research.

20. -END-

21. FLAME EMISSION SPECTROMETRY

22. Flame emission spectrometry
● Method that uses a flame to cause an atomized analyte to emit its
characteristic emission spectrum.
● Also known as flame photometry.
● It closely resembles other techniques of optical emission spectrometry in
principle and instrumentation. The difference lies in the substitution of a
chemical flame for the high temperature electric discharges or plasmas.
● It follows that the flame-induced emission spectrum of an element will be
much less complex than the corresponding spectrum resulting from an
electric discharge or plasma.
● Useful technique for the determination of volatile elements with low
excitation energies such as the alkali and alkaline earth metals.

23. CONTENTS:
1. Overview/Instrumentation
2. Strengths / Limitations
3. Applications

24. 1. Overview/Principle
Emission of electromagnetic radiation in the visible and ultraviolet
regions of the spectrum by atoms after electronic excitation in flames.
When metal ions are heated, they
emit light. And these light are
measured by their wavelengths.

25. 1. Overview/Principle

26. 1. Overview/Principle

27. 1. Overview/Principle

28. 2. Strengths/Limitations
● If a sample contains multiple different metal ions the spectrum will show
the lines for all of them.

29. 2. Strengths/Limitations
● Intensity of emission is very sensitive to changes in flame temperature.
Spectral interferences and self-absorption are common problems.

30. 3. Applications
○ Flame emission spectrometry is used extensively for the determination of trace metals in
solution and in particular the alkali and alkaline earth metals.
○ It also can be used to identify and quantify a variety of elements that are important to the
studies on enzymes and metalloproteins.
○ The most notable applications are the determinations of Na, K, Ca and Mg in body fluids
and other biological samples for clinical diagnosis.
○ Simple filter instruments generally provide adequate resolution for this type of analysis.
The same elements, together with B, Fe, Cu and Mn, are important constituents of soils
and fertilizers and the technique is therefore also useful for the analysis of agricultural
materials.
○ Although many other trace metals can be determined in a variety of matrices, there has
been a preference for the use of atomic absorption spectrometry because variations in
flame temperature are much less critical and spectral interference is negligible.
○ Detection limits for flame emission techniques are comparable to those for atomic
absorption, i.e. from < 0.01 to 10 ppm.
○ Flame emission spectrometry complements atomic absorption spectrometry because it
operates most effectively for elements which are easily ionized, whilst atomic absorption
methods demand a minimum of ionization.

31. -END-