Table of Contents
Caking may be prevented by designing suspensions with a structured network that supports the particles and keeps them from entering a close-packed array. The network may consist of suspending agent (structured vehicle), the particles themselves (flocculated), or a combination of the two.
How can I make my suspension more stable?
There are some useful methods to improve the physical stability of a suspension, such as decreasing the salt concentration, addition of additives to regulate the osmolarity, as well as changes in excipient concentrations, unit operations in the process, origin and synthesis of the drug substance, polymorphic behavior
What is caking in suspensions?
The main problem dealt with in this article is preventing the aggregation of particles in a suspension — extensive aggregation can lead to ‘caking’. This is the process in which almost all particles in the sediment become interconnected, making it impossible to resuspend.
What are 3 types of suspension?
There are three basic types of suspension components: linkages, springs, and shock absorbers.
Which cation is most stable?
(CH3)3C+3∘ carbonium ion is most stable.
What is suspending agent?
: a substance (such as carrageenan, xanthan gum, or cellulose ether) that is added to fluids to promote particle suspension or dispersion and reduce sedimentation All these drinks can contain preservatives, and drinks other than juices can contain additives to colour, flavour and sweeten.
Is the instability condition of a suspension?
It is important to understand that suspensions are kinetically stable, but thermodynamically unstable, system. Physical stability is defined as the condition in which the particles remain uniformly distributed throughout the dispersion without any signs of sedimentation. It is difficult to achieve this condition.
What is difference between flocculation and Deflocculation?
The key difference between flocculation and deflocculation is that flocculation is the formation of flocs by the clumping of fine particles, whereas deflocculation is the dispersion of flocs to form a stable colloid. Flocculation refers to the formation of clumps from fine particles in a colloid.
What causes flocculation?
In dispersed clay slurries, flocculation occurs after mechanical agitation ceases and the dispersed clay platelets spontaneously form flocs because of attractions between negative face charges and positive edge charges.
Which is more stable Fe2+ or Fe3+?
Fe3+ is more stable than Fe2+. In Fe3+ ions, there are five 3d half-filled orbitals and is more symmetrical than Fe2+. Whereas in Fe2+ ion there are four 3d half-filled orbitals and one orbital is filled.
Is a true solution stable?
In a True solution the solute particles are very small (less than 1nm) so they easily mix in the solvent. Colloid particles are also small but larger than true solution(1nm to 100nm) so they also mix and do not settle at the bottom.
How is caking prevented?
The solution to a caking problem is to induce inter-particle motion at some critical time based on the flow properties. Thus, to solve caking problems, we often need a mass flow design with sufficient velocity profile to induce inter-particle motion and prevent the cementation or caking of material.
Which suspension is more stable and why?
Suspension is more stable. This is because suspension does not mix with each other. The denser particles settle down at the bottom and makes the solution stable.
Which type of suspension is best?
Engineers have tackled this problem with varying degrees of complexity, but the best known are the MacPherson Strut, double wishbone and multi-link systems. As one of the simpler and therefore cheaper options for independent suspension, the MacPherson strut has seen widespread use since its invention back in the 1940s.
What are the physical instability markers in suspension?
All suspensions, including coarse emulsions, are inherently thermodynamically unstable. They will, through random motion of the particles over time, aggregate because of the natural and dominant tendency to decrease the large specific surface area and excess surface energy.
Is a suspension stable?
Suspension Stability Increasing the zero-shear viscosity of the continuous phase of an emulsion or suspension is a popular method of increasing physical stability. Controlled stress measurements on high performance rheometers are a necessity for zero-shear viscosity testing.
How do I know if my suspension is stable?
Suspension stability can be theoretically estimated prior to the beginning of the formulating process based on the solid phase particle size, liquid phase density, and viscosity. Stokes equation can be used to predict suspension stability in order to save time and resources.
How does flocculation prevent caking?
Flocculating agents are electrolytes which carry an electrical charge opposite that of the net zeta potential of the suspended particles. As we can see from Stoke’s Law, if we apply flocculation as a means of preventing caking, then we will increase the particle diameter, and thus increase the rate of sedimentation.
What are the 4 types of suspension?
Car Suspension 101: Understanding the Four Types of Spring Systems
- Leaf Springs. Leaf springs are made up of a cascading set of blades held together by a U-bolt.
- Coil Springs. If you know what a Slinky is, then you know what a coil spring looks like.
- Torsion Bars.
- Air Springs.
Why do Flocculated particles not cake?
Repulsive forces between particles are overcome and a hard cake is formed which is difficult, if not impossible, to redisperse. The sediment is loosely packed and possesses a scaffold-like structure (large volume of final sediment). Particles do not bond tightly to each other and a hard, dense cake does not form.
How do you overcome the instability of suspension?
Increasing the viscosity – increasing the viscosity of the continuous phase can lead to the stability of suspensions. This is so because the rate of sedimentation can be reduced by increase in viscosity. Viscosity increase is brought about by addition of thickening agents to the external phase.
Which agent is used for stability of suspension?
Xanthan gum in drug delivery applications XG is widely used as a suspending agent and stabilizer in suspension due to its safety properties in food and drug applications. Moreover, it is soluble in water and can provide sufficient viscosity in low concentration.
What are the reasons behind the formulation of a pharmaceutical suspension?
The reasons for the formulation of a pharmaceutical suspension: — when the drug is insoluble in the delivery vehicle. –To mask the bitter taste of the drug. –To increase drug stability.
What is a suspension in pharmacy?
A pharmaceutical suspension is a coarse dispersion of insoluble solid particles in a liquid medium. In addition, when compared to solution dosage forms, relatively higher concentration of drugs can be incorporated into suspension products.
What are signs of suspension problems?
Suspension Warning Signs
- Continued bouncing after hitting bumps or a dipping when braking.
- A drifting or pulling to one side when turning corners.
- One side of the parked car sitting lower than the other side.
- Difficult steering.
- Unusually bumpy rides.
