A further approach to quantitative determinations by thin layer chromatography

In the proposed method, an internal standard, suitably chosen, is added in equal quantities to the sample was well as to the standard solutions. A standard curve is obtained by plotting the ratio Ds/Di for each of the standard solutions against the logarithm of the quantity of material present in each solution, where Ds and Di are the average diameters of the standard and internal standard spots, respectively. It was disclosed that the ratio Ds/Di for a given solution is constant, regardless of the volume of the solution spotted. As a result, no exact equal known volumes are needed for spotting. The method has been tested with estimation of menthol in volatile oil of peppermint and strychine in nux vomica seed.