What is RRT?

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Relative retention time (RRT) is the ratio of the retention time of analyte peak relative to that of another used as a reference obtained under identical conditions.

RRT = (T analyte / T reference)
 Wher T = Retention time

As per USP

Relative retention time (RRT): Also known as the “unadjusted relative retention”.

Comparisons in USP–NF are normally made in terms of unadjusted relative retention, unless otherwise indicated.

RRT = tR2/tR1

The symbol rG is also used to designate unadjusted relative retention values.


The use of the relative retention time (RRT) reduces the effects of some of the variables that can affect the retention time.


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