EVALUATION OF PURE COUMARINS USING TLC-DENSITOMETER, SPECTROPHOTOMETER, AND HPLC WITH PHOTODIODE-ARRAY DETECTOR

A comparison of the UV spectra of twenty seven pure coumarins was carr ied out using TLC-densitometer, spectrophotometer and high performance liquid chromatography (HPLC) with photodiode array detector (DAD). Th e data obtained from TLC-densitometer and HPLC in reference to those o f the spectrophotometer showed that the dependencies were statisticall y highly significant. Regardless of the structure of the coumarin, a c ommon lambda(max) and/or lambda(min) can be detected by the different UV off/on-lines. A shift in the absorption bands measured by TLC-W and HPLC was noticed when compared to those measured by the spectrophotom eter and the intensities of the absorption bands were mot the same amo ng the different UV off/on-lines.