Morphine and morphine 3--D-glucuronide were separated on two different 4.6-mm-diameter 50-mm-long columns with 3-m particles.39 Column A was C18-silica run at 1.4 mL/min, and column B was bare silica run at 2.0 mL/min. (a) Estimate the volume, Vm, and time, tm, at which unretained solute would emerge from each column. The observed times are 0.65 min for column A and 0.50 min for column B. (b) Column A was eluted with 2 vol% acetonitrile in water containing 10 mM ammonium formate at pH 3. Morphine 3--D-glucuronide emerged at 1.5 min and morphine at 2.8 min. Explain the order of elution. (c) Column B was eluted with a 5.0-min gradient beginning at 90 vol% acetonitrile in water and ending at 50 vol% acetonitrile in water. Both solvents contained 10 mM ammonium formate, pH 3. Morphine emerged at 1.3 min and morphine 3--D-glucuronide emerged at 2.7 min. Explain the order of elution. Why does the gradient go from high to low acetonitrile volume fraction? (d) Find the retention factor k for each solute on column A, using tm 0.65 min. (e) From Equation 24-10 in Box 24-4, estimate k*, assuming S 4 and with tm 0.50 min. NCH3 HO H HO HO2C HO HO OH O O Morphine Morphine 3--D-glucuronide NCH3 O H HO O O C6H5 CH3 CO2H OH CH3 N N 632 CHAPTER 24 High-Performance Liquid Chromatography 24-21. The rate at which heat is generated inside a chromatography column from friction of flowing liquid is power (watts, W J/s) volume flow rate (m3 /s) pressure drop (pascals, Pa kg/[m s 2 ]). (a) Explain the analogy between heat generated in a chromatography column and heat generated in an electric circuit (power current voltage). (b) At what rate (watts J/s) is heat generated for a flow of 1 mL/min with a pressure difference of 3 500 bar between the inlet and outlet? You will need to convert mL/min to m3 /s. Also 1 bar 105 Pa.
Chemistry week 5 9/ 28 • Water is amphiprotic, can donate or accept protons • Water can be acid or base • pH + pOH = 14 + o example: H O + 2H O 2 H3O + OH § arrows going both ways show: • equilibrium • rate of going forward is equal to the rate of