Q5 lon Chromatography A 20 L sample solution, containing approximately 3 mM sodium nitrate and 2...

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Q5 lon Chromatography A 20 μL sample solution, containing approximately 3 mM sodium nitrate and 2 mM calcium sulfate in water, was injected into an anion exchange chromatograph and eluted with 8.0 mM KOH at a flow of 1.2 mL/min. The column had a capacity of 30 ueq and void volume of 2.0 mL. The system and resulting chromatograph is shown below. a) Explain why the peaks in the top chromatogram are negative, whereas the peaks in the bottom chromatogram are positive. (2) b) According to theory, which peak should be the broadest. Why? (4) c) How would an AERS suppressor work in this system? (3) d) Calculate the effective ion exchange site concentration of the column, Ca, in meq/L. (1) Calculate the width of the sample plug at injection, in seconds. (2) e) f) Calculate to expected for this system, in minutes. (1) g) State Cmax for nitrate and Cas for sulfate in mM. Explain why these values are different. (2) Question 5=2+4+3+1+2+1+2-15 marks Sample NANG CHO Separator Suppressor H₂² Celon-exchange mentrane KOH luent Anion separator column (strong- base anion exchanger in OH fon NOV Towe Anion chromatography Conductty Conductivity detector (K),50 Elion time I K'OH KO Q5 lon Chromatography A 20 μL sample solution, containing approximately 3 mM sodium nitrate and 2 mM calcium sulfate in water, was injected into an anion exchange chromatograph and eluted with 8.0 mM KOH at a flow of 1.2 mL/min. The column had a capacity of 30 ueq and void volume of 2.0 mL. The system and resulting chromatograph is shown below. a) Explain why the peaks in the top chromatogram are negative, whereas the peaks in the bottom chromatogram are positive. (2) b) According to theory, which peak should be the broadest. Why? (4) c) How would an AERS suppressor work in this system? (3) d) Calculate the effective ion exchange site concentration of the column, Ca, in meq/L. (1) Calculate the width of the sample plug at injection, in seconds. (2) e) f) Calculate to expected for this system, in minutes. (1) g) State Cmax for nitrate and Cas for sulfate in mM. Explain why these values are different. (2) Question 5=2+4+3+1+2+1+2-15 marks Sample NANG CHO Separator Suppressor H₂² Celon-exchange mentrane KOH luent Anion separator column (strong- base anion exchanger in OH fon NOV Towe Anion chromatography Conductty Conductivity detector (K),50 Elion time I K'OH KO

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