Page 174 - An Introduction to Analytical Atomic Spectrometry - L. Ebdon

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12 'The ICP provides the most useful atom cell for atomic emission spectrometry'. Critically discuss
this statement with particular reference to the analysis of 'real' samples.

13 Discuss the relative advantages and disadvantages of:

(a) atomic emission and atomic mass spectrometry;
(b) flames and electrothermal atomizers;
(c) hydride generation.

14 'There have been claims that of ICP-AES and ICP-MS, one is superior to the other as an analytical
technique'. Discuss this statement critically.

15 Discuss in detail the origins and effects of interferences in ICP atomic emission and ICP mass
spectrometry, and describe how they may be minimized or eliminated in practice. Explain why some of
these interferences are common to both methods. Illustrate your answer with suitable examples where
appropriate.

16 Discuss, with appropriate reference to basic theory, the reasons for five of the observations in ICP
mass spectrometry listed below:
(a) Copper can be determined more sensitively than chloride.
(b) In the determination of arsenic in an effluent containing large amounts of sodium chloride, the
apparent arsenic signal at m /z 75 was reduced when the sample was pretreated by passing it through an
anion-exchange column.
(c) The lead 204/208 isotope ratio observed for an isotopic standard was 10% less than the certified
value.
(d) The determination of antimony in a lead sample gave a low result when compared with aqueous
standards, but improved when the sample was diluted.
(e) Far fewer spectroscopic interferences are observed with a magnetic sector compared to a quadrupole
mass analyser.
(f) The determination of iron in water is greatly improved by the use of 'cool plasma' conditions.

17 Outline methods for performing the following determinations (approximate levels of the analytes
are given in parentheses):
(a) sodium in soil extracts (50 mg 1 );
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(b) manganese in cast iron (0.1%);
(c) tetraethyllead in petrol (300 mg l );
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(d) arsenic in trade effluent (0.1 mg l );
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(e) magnesium in tap water (20 mg l );
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(f) cadmium in tap water (1 µg l );
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(g) lead in blood (30 µg 1 );
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(h) bismuth in nickel alloys (1 µg g );
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(i) mercury in seaweed (50 ng g ).
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