Physical vapour transport of urotropine: one-dimensional model

A simple method suitable for the first estimation of the presence of volati le (inert) impurities in physical vapour transport systems is reported. The method, which is based on the use of a one-dimensional steady-state model, allows to calculate the overall pressure in the system when experimental a nd calculated mass transport rates are matched. When applied to the physical vapour transport of polycrystalline urotropine , the method proved suitable for evidencing the presence of volatile impuri ties whose partial pressures can be estimated to exceed the partial pressur e of urotropine vapours of about one order of magnitude. (C) 2000 Elsevier Science S.A. All rights reserved.