multicolumn(3)(|c|){ Table 27.5 The'required' hydrophilic-lipophile balance values for oils and oil phase ingredients Oil & Oil-in-water emulsion & Water-in-oil emulsion Petrolatum & 7-8 & 4 Liquid paraffin & 10.5 & 4 Mineral oil, light & 12 & 4 Castor oil & 14 & - Lanolin, anhydrous & 12 & 8 Beeswax & 9 & 5 Cottonseed oil & 6 & - Pine oil & 16 & - A formulator is required to formulate an oil-in-water emulsion of the basic formula: Liquid paraffin Emulsifying agents (required HLB 10.5) 50 mathrm(~g) 5 mathrm(~g) Water To prepare this liquid paraffin-in-water emulsion, the nonionic emulsifier, or mixture of nonionic emulsifiers, should have the required HLB value of 10.5. This narrows the number of possible surfactants considerably. Although a single surfactant with this HLB value may be suitable, usually it is better to have a mixture of emulsifiers, one with a lower HLB value than required and the other with a higher HLB value than required. In this formulation, suitable emulsifiers are Tween 80 (with an HLB value of 15) and Span 80 (with an HLB value of 4.3). To calculate the fraction x of Tween 80, Eq. 27.2 gives [ } 10.5 & =x times 15+(1-x) times 4.3 15 x-4.3 x & =10.5-4.3 ( is ) 10.7 x=6.2 x & =0.58 ] Thus to match the required HLB of the oil, the fraction for percentage = fraction x 100) of Tween 80 is 0.58(88 %) and that of Span 80 is 0.42(42 %) . Thus 2.9 mathrm(~g)(0.58 times 5) of Tween 80 and 2.1 mathrm(~g)(0.42 times 5) of Span 80 are required for this formulation.

Question

multicolumn(3)(|c|){ Table 27.5 The'required' hydrophilic-lipophile balance values for oils and oil phase ingredients Oil & Oil-in-water emulsion & Water-in-oil emulsion Petrolatum & 7-8 & 4 Liquid paraffin & 10.5 & 4 Mineral oil, light & 12 & 4 Castor oil & 14 & - Lanolin, anhydrous & 12 & 8 Beeswax & 9 & 5 Cottonseed oil & 6 & - Pine oil & 16 & - A formulator is required to formulate an oil-in-water emulsion of the basic formula: Liquid paraffin Emulsifying agents (required HLB 10.5) 50 mathrm(~g) 5 mathrm(~g) Water To prepare this liquid paraffin-in-water emulsion, the nonionic emulsifier, or mixture of nonionic emulsifiers, should have the required HLB value of 10.5. This narrows the number of possible surfactants considerably. Although a single surfactant with this HLB value may be suitable, usually it is better to have a mixture of emulsifiers, one with a lower HLB value than required and the other with a higher HLB value than required. In this formulation, suitable emulsifiers are Tween 80 (with an HLB value of 15) and Span 80 (with an HLB value of 4.3). To calculate the fraction x of Tween 80, Eq. 27.2 gives [ } 10.5 & =x times 15+(1-x) times 4.3 15 x-4.3 x & =10.5-4.3 ( is ) 10.7 x=6.2 x & =0.58 ] Thus to match the required HLB of the oil, the fraction for percentage = fraction x 100) of Tween 80 is 0.58(88 %) and that of Span 80 is 0.42(42 %) . Thus 2.9 mathrm(~g)(0.58 times 5) of Tween 80 and 2.1 mathrm(~g)(0.42 times 5) of Span 80 are required for this formulation.

Answer 1

### To prepare the emulsion, use 2.9 g of Tween 80 and 2.1 g of Span 80.

Answer 2

## Step 1: Understanding the Problem### The task is to formulate an oil-in-water emulsion using liquid paraffin, which requires a hydrophile-lipophile balance (HLB) value of 10.5. We need to use a mixture of emulsifiers to achieve this HLB value.## Step 2: Identifying Suitable Emulsifiers### Two emulsifiers are considered: Tween 80 with an HLB value of 15 and Span 80 with an HLB value of 4.3. A combination of these two will be used to achieve the desired HLB of 10.5.## Step 3: Setting Up the Equation### The equation to calculate the fraction

of Tween 80 in the mixture is given by:

## Step 4: Solving the Equation### Rearrange and solve for

:

## Step 5: Calculating the Amounts of Emulsifiers### The fraction of Tween 80 required is 0.58 (or 58%), and the fraction of Span 80 is

(or 42%). For a total of 5 grams of emulsifier mixture:- Tween 80:

grams- Span 80:

grams

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