Characterization of lactose powder surfaces by isothermal microcalorimetry

Several lactose samples containing various amounts of amorphicity were stud ied with an isothermal microcalorimetric technique, which allow to detect t he heat and the quantity of water sorption simultaneously. As interaction w ith vapor is characteristic of different surfaces, the samples were easy to be discriminated from each other by studying sorption behavior. With the c rystalline lactose samples, the amount of sorbed water was too minor to be detected reliably with the technique, but differences were found when the e nergy values (J g(-1)) were compared. In the future work, the measurement s et-up will be improved so that sorption rates less than 0.1 nmol s(-1) can be measured repeatably and reliably.