Novel analytical method of Analysis should be developed to suite the requirements of laboratory conditions such as change in sample processing procedure, instruments. The method should be fulfill laboratory conditions, followed by validation .HPLC is an efficient tool providing low detection limits, reduces influence of interferences and the possibility of short run times.In HPLC, the separation techniques for active drugs from Bulk and Pharmaceutical dosage froms with critical step leading to drug discovery with least interference. Hence A new Analytical method for the estimation of LEvocitrizine and Escitalopram and thier preservatives in oral dosage form can be developed. The developed Analytical method was validated as per FDA guidelines. Это и многое другое вы найдете в книге Determination of Levocetrizine and Escitalopram in Oral Solution (Krishna Chaitanya Koppula,Gowri Sankar Dannana and Samson Israel Deta)