Spectroscopy Ii- Hplc & Raman

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UNIVERSITI TUNKU ABDUL RAHMAN Faculty Course Year/ Semester Session : : : : Faculty of Science Bac. of Science (Hons) Chemistry Year 3 Semester 1 201105 or May 2011 Unit Code Unit Title Lecturer Assignment : : : : UDEC3254 Spectroscopy and Chromatography II Dr. Lim Chan Kiang 2 Answer all questions 1. A mixture of steroid hormones consisting of cortisone, cortexone and corticosterone was separated using a HPLC silica column eluted with a binary mixture of acetone and hexane (20:80). (i) What is the order of elution time for the above compounds from the HPLC column? (3 marks) (ii) What is the chromatographic mechanism involved? Describe how the mechanism effects separation to the three compounds. (8 marks) (iii) With explanation, describe what would happen to the peaks in the chromatogram when the packing silica with a larger pore size and smaller surface area is used in the above separation. (6 marks) 2. A mixture of Br-, Cl- and PO43- ions was subjected to an anionic column packed with polym-N(CH3)3+OH-, eluted with 9mM sodium carbonate. (i) Arrange the above analyte ions in order of increasing retention time in the anionic column. (3 marks) (ii) Describe how the analyte ions were separated in the anionic column according to order of retention time answered in part (2)(i). (8 marks) 3. An unknown compound is irradiated with an excitation photon. An anti-Stokes line is observed at 439.3 nm corresponding to shift of – 2270 cm-1. i) What is the excitation photon used in the irradiation above? (2 marks) ii) Find the wavenumber and wavelength of the Stokes line and anti-Stokes line with shifts of 3270 cm-1 and – 1170 cm-1, respectively. (6 marks) iii) A Stokes line supposed to be found in the region 490 nm to 500 nm in the Raman spectrum was swamped by fluorescent band. Describe how to solve the problem so that the Raman shift for the Stokes line can be

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