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A wide gradient from 5% to 100% acetonitrile applied over 49.5 min is used to se

ID: 1062128 • Letter: A

Question

A wide gradient from 5% to 100% acetonitrile applied over 49.5 min is used to separate a mixture of 12 compounds. The sample is injected at t dwell time. The first compound elutes from the column at 17.0 min and the last compound elutes at 33.8 min. From this run, it was determined that gradient elution would be appropriate for the separation of this mixture of compounds. Based on these results, determine the appropriate starting and ending values for the percent acetonitrile in the solvent for the second run over the same gradient time Number Number to acetonitrile From

Explanation / Answer

Starting % of ACN = initial % + ratio of initial time ( 100-initial%)

= 5 + 17/49.5 * (100-5) = 37.67%

For

Ending % ACN = Initial + % ratio (100-initial%)

= 5 + 33.8/49.5 *(100-5) = 69.8686 %

Then

the range --> goes from 37.67 ----> 69.866 %

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