4743
Thin-layer chromatography of some plant phenolics
In the course of studies on the role of phenolics in plant metabolism it became necessary to separate and identify a number of phenolic compounds. Although there have been many reports in the literature on thin-layer chromatography (TLC) used for this purposea-much of the information available for the compounds of interest has been obtained using paper chromatography o--8. In order to obtain the advantages of speed and sensitivity available with TLC we felt it necessary to determine the RF values of various standards by this technique.
TLC was carried out on 20 x 20 cm MN-polygram CEL 300 cellulose sheets obtained through Brinkmann Instruments, Inc. The solvents used were z o/O formic acid (A), 20% potassium chloride (B), isopropyl alcohol-ammonium hydroxide-water, 8 :I :I (C), and 10% acetic acid (D). The solvents were prepared fresh immediately before use. The plates were examined under short-wave UV light after developing and the properties of the compounds were noted. The plates were then sprayed with freshly prepared diazotized $-nitroaniline or diazotized sulfanilic acid1 and the colors which developed were noted within 20 min.
The characteristics of a number of phenolics, coumarins and flavonoids in this system are reported in Table I. Detection of the compounds could be made at the 0.2-1.0 pug range. TARLE I CHARACTERISTICS OF SOME PHENOLICS, FLAVONOIDS AND COUMARINS Co~mpoacnd R I.-Detection A B C D UV DSA DNA _____....__.