The Relequa ERH test has recently been used to investigate moisture profiling applications in prospective formulation and process development.
The test was used to look at the moisture profiles of two different grades of an excipient.
In the formulations, the investigators were searching for any evidence of matrix formation upon wet mixing.
Using the Relequa ERH test, moisture profiles were generated for samples of wet granulations after adding aliquots of water, starting with dry powder mixes.
Two formulations were tested containing different grades of an excipient.
Moisture profiles were compared graphically.
One formulation showed evenly spaced Relequa ERH moisture profiles as water aliquots were added.
This is consistent with the simple wetting of the ingredients.
The graph of Relequa ERH moisture profiles for the other formulation was different; it showed a region where the moisture profiles were grouped together.
This was interpreted as the grouping together of the Relequa ERH moisture profiles as the formation of a matrix that has a capacity for binding water.
This matrix 'buffers' against the availability of free moisture as water is added.
This buffering continues until a breakthrough point is reached, until the material becomes too wet and until it has a much increased ERH.
This opens up possibilities for the Relequa moisture test to be used as an investigational tool for wet granulation trials and in quality-by-design (QbD) applications.
