Emulsion Formulation by HLB Method

• Emulsion Formulation by HLB Method selects surfactants based on hydrophilic-lipophilic balance for stability.
• It ensures proper oil-water blending in pharmaceuticals and cosmetics.
• HLB (Hydrophilic–Lipophilic Balance) is a numerical scale (0–20) used to select appropriate emulsifying agents based on their balance between hydrophilic and lipophilic portions.

HLB Scale Interpretation

HLB Value	Nature of Surfactant	Application
1–4	Highly lipophilic	W/O emulsifiers
8–18	Hydrophilic	O/W emulsifiers
7–9	Wetting agents	Solids dispersion
13–15	Detergents	Cleansing agents
15–18	Solubilizers	Miscibility enhancers

Step-by-Step Formulation using HLB:

How to Use the HLB Method

1. Determine the required HLB (rHLB) of the oil phase (usually provided or determined experimentally).
2. Choose surfactants with known HLB values.
3. Blend two or more surfactants to match the required HLB of oil phase.

HLB Blending Formula

• Use Griffin’s equation:
• $\text{HLB}_{\text{blend}} = f_A \cdot \text{HLB}_A + f_B \cdot \text{HLB}_B$
• Where:
  • $f_A f_B$ = weight fraction of each emulsifier
  • $\text{HLB}_{A} \; \text{HLB}_{B}$ = individual HLB values

Example

• If an oil phase requires an HLB of 10, and you have:
• Surfactant A with HLB = 12
• Surfactant B with HLB = 4
• To find proportion of A (x) and B (1-x):

$10 = x(12) + (1 – x)(4)$

$10 = 12x + 4 – 4x \;\Rightarrow\; 6x = 6 \;\Rightarrow\; x = 1$

So, use 100

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