Problem_Set_V_-_High-Performance_Liquid_Chromatography

Problem_Set_V_High - of 2-8 6 HPLC peaks generally should not have an asymmetry factor outside the range of 0.9-1.5(a Sketh the shape of a peak

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Problem Set V – High-Performance Liquid Chromatography 1. Why does eluent strength increase as solvent becomes less polar in reversed phase chromatography, whereas eluent strength increases as solvent becomes more polar in normal phase chromatography? 2. (a) Why is high pressure needed in HPLC? (b) What is a bonded phase in liquid chromatogrphy? 3. Why does small particles give better resolution? 4. If a 15 cm long column has a plate height of 5 μ m, what will be the half-width (in seconds) of a peak eluted at 10 min? If the plate height is 25 μ m, what will be w 1/2 ? 5. Why are silica stationary phases generally limited to operating in the pH range
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Unformatted text preview: of 2-8? 6. HPLC peaks generally should not have an asymmetry factor outside the range of 0.9-1.5. (a) Sketh the shape of a peak with an asymmetry factor of 1.8. (b) What might you do to correct the asymmetry? 7. (a) Nonpolar aromatic compounds were separated by HPLC on an odtadecyl (C18) bonded phase. The eluent was 65% methanol in water. How would the retention times be affected if 90% methanol were used instead? (b) Octanoic acid and 1-aminooctane were passed through the same HPLC column described in part (a), using an eluent of 20% methanol/80% buffer (pH 3.0). State which compound is expected to be eluted first and why....
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This note was uploaded on 05/09/2008 for the course PHARM.CHEM 306 taught by Professor Hu during the Spring '08 term at Rutgers.

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