A scientist wanted to separate a molecule from a contaminant in a sample. She ch

Question

A scientist wanted to separate a molecule from a contaminant in a sample. She chose to use reverse polarity capillary electrophoresis (detector at the positive terminal of the capillary) at a pH of 2.8 to perform the separation. At this pH both the molecule and the contaminant are negatively charged. Why was reverse polarity capillary electrophoresis used to separate the molecule and the contaminant instead of normal polarity capillary electrophoresis? At pH 2.8, the silanol ned wall would be neutral, thus the electroosmotic flow would be O very small and the molecules being investigated would migrate toward the positive terminal At pH 2.8, the silanol ned wall would have a positive charge, thus the electroosmotic flow would migrate from the negative to the positive terminal The scientists could have used normal or reverse polarity capillary electrophoresis and obtained the same results At pH 2.8, the silanol lined wall would have a negative charge, thus the electroosmotic flow would migrate from the positive to the negative terminal

Explanation / Answer

Best answer is A,

Si-OH = silanol gruops will NOT be able to ionize as Si-O(-); therefore it is neutraly charged,

low pH values will be able to move, therefore.

since at pH = 2.8, so the wall be neutral, meaning that the analyte will migrate toward the desired terminal

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