Crucial aspects of quantitative validation. Determination of rosmarinic acid.

Rosmarinic acid (RA), a natural phenolic compound found in many Lamiaceae herbs, is known for having a number of interesting biological activities, e.g. antiviral, antibacterial, antiinflammatory , antioxidant and moreover for its effects on Alzheimer's Disease [1-2]. The main source of this compound is Rosmarinus officinalis L.. However reports have been published on the TLC determination of RA in a variety of herbal extracts [3-7], but none provided reliable quantitative results as the proposed methods are impaired by some methodological weakness. Our work is focused on the analytical aspects of HPTLC quantitative validation. Here we present the pre- validation procedure, the linearity claiming and the calibration matrix effect as focal points in developing a validated HPTLC method. The method was validated giving rise to a dependable and high throughput procedure well suited to routine application. RA was quantified in the range of 132 - 660 ng with RSD of repeatability and intermediate precision not exceeding 2.0% and accuracy inside the acceptance limits. The method was tested on several commercial preparations containing RA in different amount.