For 2 of the 3 cases below, choose an analytical method or methods that would al

Question

For 2 of the 3 cases below, choose an analytical method or methods that would allow you to perform the analysis described Give SPECIFIC DETAILS on experimental parameters (including justification). You may also comment on sample preparation. (a) Coal-fired power plants are notorious for releasing mercury (in its elemental form Hg (l) because North American coal deposits tend to have large mercury concentrations. Describe a method to identify and quantify (i.e. show that it's mercury and how much there is) mercury emissions from a coal plant smoke stack. b) Robots have been exploring the surface of Mars since the Soviet Union's Mars 3 pro in Currently, the American opportunity is operating on the Martian surface and the Mars Science scheduled to land in August 2012. One primary of all these to for water. Describe an instrument that might work in a Martian rover: it would have to be rugged, lightweight, and able to detect water. (c) For recent archaeological samples (e.g. a few hundred years old), 14^C dating is unreliable. A more technique is to determine the L-to-D isomerisation of DNA. Basically, all living accurate After organism death, it gradually isomerises to racemic in the L-form. (50/50 L/D ratio) DNA over time. Assuming the isomerisation rate is known, how would you determine the age of some human remains found frozen on a mountain?

Explanation / Answer

a) Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) can be used for the detection and qantification of mercury. The sample is nebulised i.e broken down into a spray like form and directed onto a plasma generated by the radio frequency excitation of argon gas. The hot plasma ionises the Hg atoms in the sample, and the Hg ions are brought into the mass spectrometer where they are detected based on their m/z ratio.

b) Raman spectrometer can be used for identification of water in Mars. The method involves shining a laser light onto a sample and detecting the scattered light. The laser excites the material in the sample. For eg: if the sample contains water, charcteristic frequencies corresponding to the H2O molecular vibrations will be absobed accompanied by emission at particular frequencies, which can be used for sample identification and quantitation.

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