To Determine Sedimentation Volume of Suspensions with Various Agents

APPARATUS REQUIRED:

Measuring Cylinder

2. Mortar

3. Pestle

CHEMICALS REQUIRED:

Calcium Carbonate, Bentonite, Carboxymethylcellulose(CMC), Hydroxypropyl methyl cellulose (HPMC)

THEORY:

i) Suspension:

Suspension is a two-phase system consisting of freely divided solid particles 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. Same list of suspending agents are methylcellulose, hydroxy methyl cellulase, carboxymethyl cellulose, Hydroxymethyl cellulose, 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 (V_s) to the initial suspension volume (V_o)

Formula,

SV= V_s/V_o

Higher SV indicates better settling while lower SV indicates poor settling. The sedimentation volume (SV) is an indicator of the physical stability of the suspension. A higher SV value indicated better stability.

PROCEDURE:

5% w/v (or 5gml) of calcium carbonate suspension was weighed in 3 each butter paper. 1% i.e. 1 gm of a different suspending agents such as bentonite, sodium carboxymethyl cellulose & hydroxypropyl methylcellulose (HPMC) respectively were taken in a different vessel and added a small quantity of water and saturated well. After the powder was uniformly suspended, transferred the suspension into a separate 100ml measuring cylinder. The volume was made up to 100 ml with distilled water. The suspensions were shaken simultaneously & kept aside. Note the volume of sediment at time periods of a,10, 20, 30……..60 minutes to calculate the sedimentation volume.

OBSERVATION:

S.N.	1% Bentonite+ 5% CaCO₃			1% sod, carboxymethyl cellulose + 5% CaCO₃			1% HPMC + 5% CaCO₃
	V_s	V_o	SV	V_s	V_o	SV	V_s	V_o	SV
10min	98ml	100ml	0.98	72ml	100ml	0.72	34ml	100ml	0.34
20min	98ml	100ml	0.98	55ml	100ml	0.55	20ml	100ml	0.20
30min	97ml	100ml	0.97	50ml	100ml	0.50	16ml	100ml	0.16
40min	94ml	100ml	0.94	47ml	100ml	0.47	14ml	100ml	0.14
50min	93ml	100ml	0.93	45ml	100ml	0.45	13ml	100ml	0.13
60min	92.5ml	100ml	0.25	43ml	100ml	0.43	12ml	100ml	0.12

A graph is plotted to observe stability of suspension putting sedimentation volume in Y-axis and time in X-axis.

RESULT:

The suspension with 1% suspending agent sodium carboxymethyl cellulose exhibits the highest sedimentation volume indicating good suspension compared in others.

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