How is the retardation factor used to identify substances in plane chromatography?

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In plane chromatography, the retardation factor ( $R_{f}$ ) is a key value used for qualitative analysis to identify unknown substances.1

The $R_{f}$ value is calculated using the following formula:

$R_{f} = \frac{distance traveled by the component}{distance traveled by the mobile phase front}$

Because the retardation factor remains constant for a specific solute within a given solvent system, analysts can identify an unknown substance by comparing its calculated $R_{f}$ value against the known $R_{f}$ values of reference standards. By matching these values under identical experimental conditions, the identity of the analyte can be determined.1