Thin Layer Densitometric Determination of Rotenone and Deguelin

Abstract
Rutenone and deguelin are separated by chromatography on silver nitrate-impregnated silica gel G with chloroform acetone: acetic acid (196:3:1) solvent system. Glass plates, 20 × 20 cm, are coated with a special spreader producing a 0.25 mm layer and a 1.00 mm band at the upper end. Since additional solvent is required to saturate the thicker band, such plates give resolutions comparable to plates twice as long. Developed plates are treated with nitric acid vapor, then ammonia vapor, to produce dark spots for the rotenoids. Plates are scanned with a commercial densitometer, and the quantity of rotenoids is calculated from peak area in the resultant curve. Kecoveries of rotenone and deguelin added to extracts of Tephrosia vogelii, Lonchocarpus nicou, and Derris elliptica averaged 104.1 and 99.4%, respectively. The standard deviation of the method applied to plant extracts was 7.9% for rotenone and 8.3% for deguelin. The amounts of rotenone in the L. nicou samples were comparable to those determined by the AOAC crystallization and infrared methods.

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