Lipophilic-hydrophilic balance estimation

Inversely, the presence of ethanol and other alcohols in hydroalcoholic preparations may cause loss of solubility of hydrophilic peptides. In these products polypeptides with high hydrophobicity are preferred. The coefficient of ripartition 2-butanol/water (as nitrogen-partition coefficient) is used to estimate the lipophilic/hydrophilic balance of proteins for hydrophobic hydrolysates the nitrogen-partition coefficient value is 0.1-0.15 and lower for more hydrophilic derivatives (129). 

By the hydrophilic-lipophilic balance (HLB) system, according to Griffin (15). The HLB ratio is expressed as a number based on the emulsifying properties of the emulsifier. The HLB can also be estimated from the chemical structure according to the molecular group contributions, as repeated by Davies (16). HLB numbers are closely related to the functional properties of the emulsifiers. 

The Hydrophile-Lipophile Balance (HLB) value of a solvent can be related to the solvent s polarity and hydrogen bond character as shown by the radius of interaction / calculations of solvent and reference hydrocarbon dodecane. The HLB values of a number of solvents were determined by the Davies method [16] and plotted against the solvent s calculated R solvent/ dodecane values. The resultant linear equation from this plot (i.e., HLB = 14.306 - 3.489 log / ), was used to estimate the solvent HLB values shown in Figure 4.5 [12]. 

Soaps and surfactants are molecules, which are characterized as amphiphiles. Amphiphile is a Greek word, which means likes both kinds. A part of the amphiphile Ukes oil or hydrophobic (lipophilic = likes fat) (Tanford, 1980), while the other part likes water or hydrophilic (also called lipophobic). The balance between these two parts, hydrophilic-lipophilic, is called hydrophilic-lipophilic balance (HLB). The latter quantity can be estimated by experimental means, and theoretical analyses allow one to estimate its value (Adamson and Gast, 1997 Birdi, 2009). HLB values are applied in the emulsion industry (Birdi, 2009 Hansen, 2007). 

The PIT system provides information on the type of oil, phase volume relationships and concentration of the emulsifier. The PIT system is established on the proposition that the HLB number of a surfactant changes with temperature and that the inversion of the emulsion type occurs when the hydrophilic and lipophilic tendencies of the emulsifier just balance. At this temperature no emulsion is produced. From a microemulsion viewpoint the PIT has an outstanding feature since it can throw some light on the chemical type of the emulsifier needed to match a given oil. Indeed, the required HLBs for various oils estimated from the PIT system compare very favourably with those prepared using the HLB system described above. This shows a direct correlation between the HLB number and the PIT of the emulsion. 

What is the HLB (hydrophilic-lipophilic balance), how can it be estimated and what is its importance in the design of emulsions (maximum 20 lines) ... 

Hydrophile-lipophile balance (HLB). An essentially empirical method for quantifying or estimating the potential surface activity of a surfactant based on its molecular constitution—used primarily in emulsion technology. 

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