Question: Say you injected and x amount of protein onto the SEC column (size exclusion chromatography) and it produced certain peaks. Now say you repeated the experiment, using the same amount of protein (same concentration as the first) but the second time around the heights of the peaks differ. Can anyone explain to me why would the peak heights differ, even though the same amount of protein was used. Is it due to the fact that some of the protein remained bound to the column during the second run? Here's the question asked by my instructor . . .

Explain why if we injected the same amount of protein onto the SECcolumn, that the heights of the peaks are different - if they are all the same concentration shouldn't they all be the same? Exlpain.