Fully automated drug liberation apparatus for semisolid preparations based on sequential injection analysis Original Research Article

A novel set-up of a fully automated system based on the SIA technique connected to the liberation apparatus, Franz cell, is described. The SIA system was applied to observe different membrane materials (poly-carbonate, mixed esters of cellulose, Teflon, silicon, poly-vinylidene fluoride, etc.) and used for monitoring liberation profiles of Indomethacin 1% gel. Comparison of the liberation rates of gels and ointment prepared by different technological procedures was demonstrated. Liberation medium was 0.001 M NaOH; samples were taken in 10 min intervals during 6 h of the liberation test; and each test was followed by calibration with five standard solutions. The linear calibration range was 0.05–10 mg l−1 (r=0.9998, six standards); the sample throughput was 120 h−1, sample volume being 50 μl and flow rate 50 μl s−1. The detection limit for indomethacin determination was 0.04 mg l−1 (3σ). The optimised conditions were also used for indomethacin assay in topic formulation Indomethacin gel 1%. Results obtained with the SIA system were confirmed by conventional batch UV measurement.