Two methods for the quantification of the five main isoflavones in red clover containing
nutritional supplements using high performance liquid chromatography and high performance
thin layer chromatography were developed. Validation of both methods was performed
according to the ICH guidelines. The HPLC method was found to be rapid (25min for
a single run) and offered a good linearity, sensitivity and repeatability but caused
high operating costs due to the sophisticated instrumentation and extensive amounts
of solvent for the whole validation process. For the quantitative determination of
the five isoflavones by HPTLC, a mobile phase of dichloromethane-acetic acid-ethyl
acetate (12:2:1, v/v/v) was used which afforded sufficient separation. HPTLC allowed
simultaneous fast quantification of the isoflavones comparable to the HPLC method
and efficient distinction between different nutritional supplements. Therefore, this
inexpensive method could be used in the quality control of nutritional supplements
of red clover.