APPARATUS REQUIRED:
Measuring Cylinder, Mortar and Pestle
CHEMICALS REQUIRED:
Bentonite, Calcium Carbonate, Water
THEORY:
i) Suspension:
Suspension is a two-phase system consisting of a finely divided solid particle dispersed in liquid (solid drug in liquid vehicle) The insoluble solid drug is uniformly suspended throughout the suspending vehicle (dispersion medium) by the aid of a single combination of suspending agents.
ii) Suspending agents:
Suspending agents are the substances which are added to a suspension to increase the viscosity of the continuous phase so that the particle remain suspended for a sufficiently long time some list of suspending agents are methylcellulose, Hydroxy methyl cellulose, Carboxymethyl cellular (CMC) Hydroxypropyl methylcellulose, Bentonite, etc.
iii) Sedimentation volume (SV)
Sedimentation volume (SV) measures how well particles settle in a suspension. It is the ratio of settled solids volume (Vs)to the initial suspension volume (Vo)
Formula,
SV =Vs/Vo
Higher SV indicates better settling while lower SV suggests poor settling. The sedimentation volume is an indicator of the physical stability of the suspension. A lower SV value indicates better stability.
PROCEDURE:
5 gm calcium carbonate was weighed in 4 each butter paper. 0.5gm of bentonite was triturated with calcium carbonate with uniform mixing & adding little amount of water like slurry. After trituration, the slurry was placed in the measuring cylinder & the mortar was rinsed 2,3 times & the volume of the measuring cylinder was maintained 100ml. Similar process was repeated for 1gm, 1.5gm & 2gm bentonite. The suspension was shaken once for uniform distribution & was left undisturbed for settling upto 1 hr. The sedimentation volume was measured in 10, 20, 30, 40, 50 & 60 minutes respectively.
OBSERVATION:
| S.N. | 0.5% Bentonite+ 5% CaCO3 | 1% Bentonite+ 5% CaCO3 | 1.5% Bentonite+ 5% CaCO3 | 2% Bentonite+ 5% CaCO3 | ||||||||
| Vs | Vo | SV | Vs | Vo | SV | Vs | Vo | SV | Vs | Vo | SV | |
| 10min | 56ml | 100ml | 0.56 | 72ml | 100ml | 0.72 | 72ml | 100ml | 0.72 | 81mll | 100ml | 0.81 |
| 20min | 49ml | 100ml | 0.49 | 55ml | 100ml | 0.55 | 66.5ml | 100ml | 0.665 | 76ml | 100ml | 0.76 |
| 30min | 44ml | 100ml | 0.44 | 50ml | 100ml | 0.50 | 63ml | 100ml | 0.63 | 74ml | 100ml | 0.74 |
| 40min | 41ml | 100ml | 0.41 | 47ml | 100ml | 0.47 | 60ml | 100ml | 0.60 | 72ml | 100ml | 0.72 |
| 50min | 38ml | 100ml | 0.38 | 45ml | 100ml | 0.45 | 57ml | 100ml | 0.57 | 70ml | 100ml | 0.70 |
| 60min | 36ml | 100ml | 0.36 | 43ml | 100ml | 0.43 | 54ml | 100ml | 0.54 | 68ml | 100ml | 0.68 |
A graph is plotted to observe stability of suspension putting sedimentation volume in Y-axis and time in X-axis.
RESULT:
The suspension with 2% bentonite exhibits the highest sedimentation volume, indicating good suspension compared to lower concentrations.