Pocess for the preparation of high purity prostaglandins

A process for the purification of latanoprost acid of Formula IIa:

• which consists of purifying crude latanoprost acid of Formula IIa by gravitational chromatography on a normal phase chromatography column filled with silica gel so that the purified latanoprost acid of Formula IIa has a purity of 89.9%-99.5% and isomeric impurities of trans-latanoprost acid and 15-epi-latanoprost acid obtained in the process are not individually more than 0.15%,
• wherein a multicomponent eluent mixture is applied as eluent, and
• wherein the eluent mixture contains one or more apolar solvents, one or more polar solvents and solvent of acidic character, in a ratio of (91-73%):(24-8.7%):(0.1-4.3%).