HLB Scale (hydrophile-lipophile balance) and emulsifying Agent

HLB Scale (hydrophile-lipophile balance) and emulsifying Agent:

We discussed about the emulsifying agent(emulsifier). 

To select appropriate emulsifying agent we used the HLB SCALE system.

HLB Scale  means hydrophile-lipophile balance.

HLB  system was developed by William C. Griffin to proper selection of the emulsifying agent.

All emulsifying agents have lipophilic and hydrophilic part. HLB value of emulsifying agent is based on the lipophilic and hydrophilic group present into the emulsifying agent.

  

The HLB value is an indication of the solubility of the Emulsifying agent.Generally HLB scales  apply to the non-ionic surfactant.

HLB system has an arbitrary scale of 1 - 18.

HLB RANGE	USE
0-3	Anti foaming agent
4-6	W/O emulsifying agent
7-9	wetting agent
8-18	O/W emulsifying agent
13-15	Detergents
10-18	stabilizing agent

                                                                                                                                                                                                                                          -Higher the HLB value means more number of hydrophilic groups in the molecule.

                  Mean more water soluble or hydrophilic the surfactant is.

                   

-The lower the HLB value the more lipophilic or oil soluble the surfactant  mean more lipid soluble or lipophilic surfactant is.

-Emulsifying agents exhibiting an HLB between 3 to 6 are used to produce w/o emulsions.so they are known as w/o emulsifying agents.

-Example: span 80

-HLB value span 80 of  4.3  

-Emulsifying agents that exhibit an HLB between  6 to 9 form non-stable milky dispersion in water.

-Example: span 40

-HLB Value of span 40 is  6.7

-Emulsifying agents exhibiting an HLB between  9 to 16 are used to produce o/w emulsions. so they are known as o/w emulsifying agents. 13–16). Examples include:

-Example: Tween 65

-HLB value of Tween 65 is 10.5

some example:

HLB RANGE	USE
PEG 400 Monostearate	11.6
Span 40	6.7
Span 20	8.6
Tween 20	16.7
Tween  40	15.6
Tween 65	10.6
Tween 85	11.0
Sodium oleate	18

 

 

Emulsifier or emulsifying agent and emulsion

Emulsifier or emulsifying agents are the substance which used to increase the stability of emulsion.

  

It is also known as the emulgent. Emulgent (Emulsifying agent) is also known as the surfactants.

  

These agents have both a hydrophilic and a lipophilic part in their chemical structure.HLB scale is used to decide the which emulsifying agents shall be used 

Emulsifying agent works by following way:

1) Formation of a protective barrier

2)Reduction of interfacial tension

3) Decreasing the potential for coalescence by forming an electrical double layer.

some commonly used emulsifying agents include tragacanth, sodium lauryl sulfate, sodium dioctyl  sulfosuccinate, Spans, Tweens, CMC, poly sorbate 

Emulsifying agents can be classified according to Chemical structure

• Natural emulsifying agent
• Semi synthetic emulsifying agent
• Synthetic emulsifying agent

• Natural emulsifying agent:

The emulsifying agent which derived from natural origin is known as the natural emulsifying agent.

They are may b from plant origin or animal origin.

The plant origin emulsifying agent is carbohydrates and include gums and mucilaginous substances. They are variable in chemical composition and their emulsifying property.

Agar, tragacanth, alginates, gum, pectins,acacia, starch are the example of natural plant origin emulsifying agents.

The animal origin emulsifying agent :

Gelatin, albumin, Lecithin, cholesterol

• Semi synthetic emulsifying agent:

Semi synthetic emulsifying agent is the emulsifying agent which are mainly from cellulose derivatives.

methylcellulose, carboxymethylcellulose are example of semi synthetic emulsifying agents

• Synthetics emulsifying agent:

The agent which synthetically derived.

They are categorized as 

Cationic:

Cationic emulsifying agents are the emulsifying agent in which hydrophilic side content positive charged ion.

Example: benzalkonium chloride, benzethonium chloride

Anionic:

anionic emulsifying agents are the emulsifying agent in which hydrophilic side content negative charged ion.

Example: sodium oleate potassium oleate, triethanolamine stearate, detergents (sodium lauryl sulfate, sodium dioctyl sulfosuccinate, sodium docusate).

 Nonionic:

Nonionic emulsifying agents are the emulsifying agents in which hydrophilic both positive and negative charges.

 Example:

sorbitan esters, Spans, polyoxyethylene derivatives of sorbitan esters (Tweens), glyceryl esters 

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Definition of Emulsion, Types of Emulsion  
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