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ps1_MSHistory_C613Spr08 - paper(W Bleakney Phys Rev 1929 34...

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Chemistry C613 Mass Spectrometry Spring 2008 Problem Set 1 – MS History Due Jan 16, 2008 (at the beginning of class) Q1. The first report of using nitrogen isotopes in studying proteins came from a group at Columbia University in 1939. (In fact the report came as a ten part series, for that year). The second paper in the series describes a “simple” mass spectrometer (by today’s standards). Find the article and draw a rough sketch of the N 2 + spectrum (Fig.4) obtained for nitrogen gas and list the precision reported in the paper (any sensible units will work but the standard is parts-per-million (ppm)). Q2. Draw a rough sketch of the apparatus. How is the spectrum generated (i.e., what is the mode of separating ions)? Details could be obtained from the reference cited in the
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Unformatted text preview: paper (W. Bleakney, Phys. Rev., 1929 , 34, 157) but the schematic and x-axis on Fig. 4 should give it way. Q3. How are the ions generated in the source of this mass spectrometer? Q4. The method of generating ions in this device was a modification of a procedure discovered by A.J. Dempster. ( Phys. Rev. , 1917 , 11(4), p.316). In this report Dempster derived a merit of resolving power which is similar to what we use today. What was the resolution calculated by Dempster for the H 2 + ion? Q5. Why does the peak corresponding to the N14N15 + ion come out at a lower potential than the one from the N14N14 + ion? Based on equation 1 in the Nitrogen Isotopes paper, what is the field strength of the magnet?...
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