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Advanced Instrumental Analysis Question Paper

Advanced Instrumental Analysis

Course:Master Of Science

Institution: Kenyatta University question papers

Exam Year:2010

KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2009/2010
INSTITUTIONAL BASED PROGRAMME (IBP)
EXAMINATION FOR THE DEGREE OF MASTER OF SCIENCE
SCH 501: ADVANCED INSTRUMENTAL ANALYSIS
DATE: Wednesday, 28th April, 2010 TIME: 9.00 a.m. – 12.00 p.m.
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INSTRUCTIONS:
Answer ALL questions.
Q.1 a) Differentiate between
i) Optical rotatory and circular dichroism (4 marks)
ii) Chemical and spectral interference (3 marks)
iii) Wideline and high resolution spectra (2 marks)
iv) Single and double beam instruments (4 marks)
b) In structural investigations its advantageous to obtain spectra with both
field ionization (FI) and electron impact (EI) source. Explain this
statement and hence the working of EI source. (4 marks)
Q.2 a) State the reason(s) for the following observations in instrumentations:
i) Its possible to obtain pure vibrational absorption in the IR – region
ii) Spectrofluorometry is potentially more sensitive than
spectrophotometry.
iii) A deuterium lamp produces a continuous rather than a line
spectrum in the uv – region.
iv) Atomic emission is more sensitive to flame instability than atomic
absorption.
v) Molecular fluorescence often occurs at a wavelength that is larger
than that of the exciting radiation.
Page 2 of 2
vi) Uv/visible absorption spectrometry if more useful in quantitative
analysis than for qualitative analysis.
(12 marks)
b) What analytical technique would be most appropriate for multi-element
analysis of a small sample? What are the advantages and limitations of
this technique? (4 marks)
Q.3 a) Explain the working of the following:
i) an interference filter
ii) cross-coil detector
iii) consumption burner
(7 marks)
b) A photomultiplier detector is used in uv/visible spectroscopy but not in IR
spectroscopy. The monochromator is placed between the source of
radiation and the sample in uv/visible while it is placed between the
sample and detector in IR instruments. Explain these observations and the
working of the uv/visible detector. (7 marks)
c) Define a “temperature profile”. What is the effect of temperature on
emission and absorption? (4 marks)
Q.4 a) List two advantages of the following:
i) Narrow bandwidth
ii) Gratings
iii) Laser sources
(4½ marks)
b) i) Explain why it is difficult to obtain NMR of solid samples.
(2 marks)
ii) Explain the environmental effects on an NMR spectra.
(3 marks)
c) i) Explain two requirements for molecules to absorb IR radiations.
(2 marks)
ii) EMR is emitted when excited particles return to ground state.
What causes excitation? (4 marks)
iii) The output of radiation services should be stable. How is
instability catered for? (3 marks

Advanced Instrumental Analysis Question Paper

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