Page 84 - Instrumental Analysis - Pharm D Clinical- 07-PA403

Location of the analyte on the TLC plate is
defined by Rf (retention or retardation factor) value

• Rf value

= distance migrated by an analyte (Da)
distance migrated by the solvent (Ds)

Rf value is the ratio of the migration

distance of the compound of interest
to the mobile phase front.

Rf value is characteristic for each

compound (when using a specific
chromatographic system)

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Pharmaceutical Applications of TLC

- Identification test: comparing with standard
substance
TLC is one of the tests stated in the pharmacopeial
monograph of drug substances and pharmaceutical
products

- Purity test: TLC is used to perform limit tests for
impurities in many pharmacopeial monographs

- Quantitative determination of an unknown
concentration using the HPTLC technique

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