Exam%203%202006%20+%20Answers

Exam%203%202006%20+%20Answers - Chem 454 Exam 3 April 19,...

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Chem 454 – Exam 3 – April 19, 2006 Show all work for full credit. 100 total points 1] What would be the relative advantages and disadvantages of using FT-IR as a HPLC detector? Discuss at least 2 advantages and 2 disadvantages. Comment on the universality (or lack of) of the detector (20 points) 2] What is meant by the term “population inversion” in its description of lasers? How is this phenomenon achieved? Contrast this to the Boltzmann distribution. Is it possible to reach population inversion based on the effects of heating? (20 points) 3] How does the capillary column configuration achieve its advantages over the packed column setup in gas chromatography? (10 points) 4] What is pulsed flow in HPLC, why does it occur, and why is this not a desirable feature? (10 points) 5] What is an FID and how does it work? What types of analytes does the FID respond to? (10 points) 6] Explain electroosmotic effect necessary for flow and separation in CE. What are the migration time trends for cations, anions, and neutral species? (10 points) 7] An HPLC analysis was conducted for caffeine on “Super-Extra-Energy Formula 2.2 with Hyper-Drive Now!” sports drink. A 10.1 ppm methanol IS standard was introduced both into the sample and a standardized solution of 304 ppm of caffeine. The measured by a diode-array detector at each λ max for the absorptions for methanol and for caffeine are summarized in the table below. What is the concentration of caffeine in that sports drink? (20 points) I S C a f f e i n e Sample 23141 52777 304 ppm Caffeine standard 28441 77313
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Answers 1] What would be the relative advantages and disadvantages of using FT-IR as a HPLC detector? Discuss at least 2 advantages and 2 disadvantages. Comment on the universality (or lack of) of
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Exam%203%202006%20+%20Answers - Chem 454 Exam 3 April 19,...

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