Quantitative determination of valienamine and validamine by thin-layer chromatography

A simple and valid thin-layer chromatographic method for the separation and quantitative determination of valienamine and validamine is described. The two compounds are separated using a Silica gel G plate as the stationary phase and a mixture of 1-PrOH-AcOH-H2O (4:1:1, v/v/v) as the mobile phase. The plate is developed for 1 h at 25 degrees C and dried by a hairdrier, then immersed in 0.1% ninhydrin aqueous solution and heated for 5 min at 121 degrees C. The reacted spots are scanned with a single wavelength at 420 nm in the measurement mode of absorption. The limits of detection of the two compounds are both 0.4 microg. The responses of the densitometry are highly correlated with the amounts of valienamine and validamine in the range of 0.4-2.8 pg. Moreover, the method shows good accuracy and high precision.