# Plate Theory and Extensions - Quantitative Analysis from Retention Measurements > Page 49

Now, there is a direct relationship between retention volume measured in plate volumes and the equivalent times, which is depicted in Figure 14.

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**Figure 14.
Relationship Between Plate Volumes and Time**

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If (t_{A}) and (t_{B}) are the retention times of solutes (A) and (B)
respectively from Figure 14 by simple proportion, .

Thus, equation (43) can be put in the form

(44)

The variable (v) is replaced by the variable (t), the elapsed time, which is the parameter that can be accurately measured.