**4.5 Active ingredient stability**

The active ingredient stability is quantified by suitable analytical techniques like HPLC, GC–MS, LC–MS, and others. According to the active constituents after formulation development. The active constituent's stability is crucial after formulation development.

## **4.6 Viscosity measurement**

Viscosity is the fundamental property of the microemulsion system. If any type of viscosity change occurs, it will destabilize the microemulsion and leads to flocculation or phase separation.

#### **4.7 Electrical conductivity**

The electrical conductivity of formulated samples in microemulsion form was checked after adding a surfactant, oil, and water components. A conductometer does this measurement at ambient temperature and 1 Hz frequency.

#### **4.8 In-vitro drug release**

The bioactive content release study was carried out in Franz diffusion cell of volume 20 ml. Two compartments are present- one is a receptor compartment, and the other is the donor compartment. Receptor compartment is filled with buffer, and the donor compartment is filled with a microemulsion sample and covered by a cellophane membrane. At certain intervals of time the donor compartment is analyzed for active ingredient content.

#### **4.9 Advantages**

of non-ionic surfactants due to de-hydration of hydrophilic groups at high temperature. In the oil phase, on the other hand, active agents'solubility increases in the oil phase. Therefore temperature optimization is critical in

*Diagrammatic representation of the effect of water on the surface-active agent on the stability of the*

For Physical appearance, microemulsion can be checked visually by the fluidity,

Transparency of microemulsion is the first sign of the microemulsion system.

Microemulsion structures can be studied by scattering of x-ray radiations. This

The droplet size of the microemulsion is measured by dynamic light scattering experiments or electron microscopy. Along with droplet size, it also gives polydis-

droplet size reduction and microemulsion stabilization.

The percent transmittance is measured by UV–visible spectroscopy.

technique identifies the nature of microemulsions weather; it is a diluted

**4. Microemulsion evaluation parameters**

*Nano- and Microencapsulation - Techniques and Applications*

optical clarity, and uniform appearance.

monodispersed or polydispersed system.

persity values of the microemulsion system.

**4.1 Physical appearance**

**Figure 4.**

*microemulsion.*

**4.2 Transmittance test**

**4.3 Scattering Techniques**

**4.4 Droplet size**

**266**


#### **4.10 Disadvantages**

