TLC determination of lovastatin

Abstract

Lovastatin causes scientific interest with features of its pharmacological and biological activity, that
causes necessity for development and improvement of simple methods of its quantitative and qualitative
determination. Today for an assessment of a lovastatin the high performance liquid chromatography is used,
but HPLC is quite labor-consuming and expensive method, in particular, for primary analysis of a large
number of samples. The favourably different is the thin-layer chromatography possessing ability of launching
of several samples simultaneously, however TLC isn't proven for determination of a lovastatin. In this
connection, the simple, fast and economical way of detection of a lovastatin is developed by method of TLC.
The selection and matching of chromatographic plates, solvent systems and a way of detection of
chromatograms are made. Optimum solvent for a chromatography is benzene-acetone (8:2). For detection of
colourless compound lovastatin are used physical and chemical methods. As a developer for plates with the
UV-indicator the ultra-violet radiation may be used. For the plates without UV-indicator the 10-% solution of
H2SO4; 0.1 N solution of KMnO4 or 10-% solution of phosphomolybdic acid may be used as a detection
reagent. Under UV-irradiation on the TLC-1A plate on a white background slightly noticeable pale pink
spots of a lovastatin are detected. On plates PTLC-AF-A-UV under UV-irradiation lovastatin is detected as
dark spots on a fluorescent background. The 10-% solution of H2SO4 provides light brown spots are formed
after dehumidification at a 100° C. The 0.1 N solution of KMnO4 provides yellow coloring of spots of a
lovastatin (PTSH-AF-A-STH-1A) on a pink background. At use of phosphomolybdic acid the dark spots on a
yellow background of a plate are formed. At increase in quantity of a lovastatin from 10 µg to 50 µg the
proportional extention of the area of a spot is also observed, that confirms an opportunity to carry out a
preliminary quantitative assessment of the content of lovastatin in area extent of a spot. The 10% solution of
phosphomolybdic acid is the best of the detecting reagent. It is possible to detect the contents more precisely
by means of elution of a spot with the suitable solvent and measurement of optical density on the
spectrophotometer at wavelength λ=238 nm, if the solvent is ethanol, and at λ=242 nm at use of chloroform.
The developed simple, fast and economic way of determination of lovastatin by method of a thin layer
chromatography may be used in the analysis of pharmaceutical preparations, researches of the intermediate
products of synthesis, and also at an assessment of natural raw materials after preliminary
purification.