Near IR spectroscopy to quantify the silica content and difference betweensilicified microcrystalline cellulose and physical mixtures of microcrystalline cellulose and silica

Silicified microcrystalline cellulose (SMCC) has been shown to have advanta ges over conventional microcrystalline cellulose (MCC). These advantages ar e (i) improved tablet strength compared to that achieved with MCC, (ii) the retention of compressibility after wet granulation, whereas MCC produces w eaker tablets after wet granulation, and (iii) superior flow properties tha n MCC. In this study near IR spectroscopy has been used to study MCC, SMCC (with different loadings of colloidal silicon dioxide, CSD) and physical mi xtures of MCC and CSD. It was found that even though SMCC and MCC were very similar, there was a region of the near IR spectra (second derivative peak at 2194 nm) where a distinctive response was seen for SMCC. The size of th e peak was proportional to the CSD content for the co-processed SMCC sample s. The peak was not present to the same extent for physical mixtures. A com bination of near IR and a test for total silica content would make it possi ble to discern whether microcrystalline cellulose samples were SMCC materia l or simple physical mixtures. (C) 2000 Elsevier Science B.V. All rights re served.