CE_Sample_Problem_Key

CE_Sample_Problem_Ke - (Ans-7.1 x 10-9 m 2/V s and-9.3 x 10-9 m 2 V s respectively From this information can you explain why Protein B elutes after

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You perform a CE experiment to separate a neutral molecule and two negatively charged proteins. The total length of the capillary is 0.840 m. The applied voltage is 2.50 x 10 4 V. The length of the capillary from the injector to the detector is 0.640 m. From your chromatogram you determine that the neutral molecule elutes in a time of 308 s. Protein A elutes in a time of 343 s and Protein B elutes in a time 355 s. Answer the following questions: 1. Calculate the electric field strength. (Ans: 29.8 kV/m) kV/m 29.8 m 840 . 0 V 10 x 2.50 L V E 4 t = = = 2. Calculate the electroosmotic velocity (u eo ). (Ans: 2.08 x 10 -3 m/s) m/s 10 x 2.08 s 308 m 0.640 t L u 3 - neutral d eo = = = 3. Calculate the apparent mobility ( μ app ) for Protein A and B. (Ans: 6.27 x 10 -8 m 2 /V s and 6.05 x 10 -8 m 2 / V s, respectively) s kV / m 10 x 05 . 6 kV/m 8 . 29 s 355 / m 640 . 0 E t / L E u E u : B s kV / m 10 x 26 . 6 kV/m 8 . 29 s 343 / m 640 . 0 E t / L E u E u : A s kV / m 10 x 6.98 kV/m 8 . 29 s / m 10 x 2.08 E u E u 2 5 - d net app app net 2 5 - d net app app net 2 5 - 3 - eo eo eo eo ep eo app = = = = μ μ = = = = = μ μ = = = = μ μ = μ + μ = μ 4. Calculate the electrophoretic mobility of Protein A and B.
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Unformatted text preview: (Ans: -7.1 x 10-9 m 2 /V s and -9.3 x 10-9 m 2 / V s, respectively) From this information can you explain why Protein B elutes after Protein A? B Protein for s kV / m 10 x 9.3-s kV / m 10 x 6.98-s kV / m 10 x 05 . 6-so A Protein for s kV / m 10 x 7.2-s kV / m 10 x 6.98-s kV / m 10 x 26 . 6-so 2 6-ep 2 5-2 5-eo app ep ep eo app 2 6-ep 2-5 2-5 eo app ep ep eo app = μ = μ μ = μ μ + μ = μ = μ = μ μ = μ μ + μ = μ The negative sign indicates that the proteins are negatively charged and are thus trying to electrophoretically move towards the anode (positive electrode). Protein B has the larger electrophoretic mobility so it must be more negatively charged then Protein A. If Protein B has a greater negative charge it can more strongly resist the pull of the electroosmotic flow as compared to Protein A, and thus comes off later....
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This note was uploaded on 11/03/2009 for the course CHEM 241 taught by Professor Tiani during the Summer '08 term at UNC.

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CE_Sample_Problem_Ke - (Ans-7.1 x 10-9 m 2/V s and-9.3 x 10-9 m 2 V s respectively From this information can you explain why Protein B elutes after

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