Effect of Sodium Carboxymethylcellulose Biopolymer on Sedimentation Properties of Trimagnesium, Tricalcium and Tristrontium Phosphates Precipitates

Sedimentation data of bioactive materials are essential in formulation of suspension with desirable requirements. Batch-wise precipitation and sedimentation tests were conducted to evaluate the effect of sodium carboxymethylcellulose (Na-CMC) biopolymer solution on the sedimentation properties (rate and compaction) of trimagnesium phosphate (TMP), tricalcium phosphate (TCP) and tristrontium phosphate (TSP) precipitates. Fixed volume (1ml) of different concentrations (200ppm - 2000ppm) of Na-CMC solution was mixed with fixed volume (50ml) of 0.5M, 0.05M Na₃PO₄ solutions. Accordingly, the resulting solutions were separately mixed with fixed volumes (50ml) of 0.5M Mg (NO₃)₂, 0.05M CaCL₂ and 0.05M SrCL₂ solutions and settling of the precipitates formed monitored. The results showed that whereas for TCP, Na-CMC exhibited a curvilinear relationship with precipitate sedimentation, non-linear relationships were observed for TMP and TSP precipitates. Between 200ppm and 2000ppm of Na-CMC addition, sedimentation rate and compaction of TCP precipitate increased by 187% and 18.5%, whereas for TMP and TSP precipitates, they increased by only (19.89% and 1%) and (30% and 0%), respectively. The results suggest that Na-CMC biopolymer is not the preferred suspending medium for suspension formulations containing TCP. For TMP and TSP precipitates, further study is needed in the light of the fact that magnesium and strontium resemble calcium.

Keywords
sedimentation rate; compaction; precipates; sodium carboxymethylcellulose