Different effect of content of material towards the characteristics of emulsion formulation

Objective

i)  To determine effect of HLB of surfactant towards the stability of emulsion

ii)  To study the physical effects and stability towards formulation of emulsion due to use of differences in emulsifying agents content

Introduction

     Emulsion is a system with two phases which is thermodynamically unstable. It usually consists of at least two liquid that immiscible. There are two types of emulsion which are oil in water (o/w) or water in oil (w/o). However, emulsion can be stabilised with the addition of emulsifying agents. Emulsifying agents can be classified into 4 different groups which are hydrophilic colloid, finely divided solid particles, surface active agents and surfactants.

     HLB is hydrophilic-lipophilic balance used to determine the quantity and type of surfactant needed to be used to make an emulsion that are thermodynamically stable. An emulsion that is thermodynamically stable will not form two different separate phases that can be distinctly recognised. An emulsion that is thermodynamically stable should have almost well mixed single phase system.

     For each and every surfactant there is an HLB value scale from 1 to 20. HLB value of 1 indicates that it is very lipophilic while 20 indicate that it is very hydrophilic. In practice, usually two surfactants are used in the preparation of more stable emulsion. HLB value of two combined surfactants is calculated using the following formulae

HLB value = [(quantity of surfactant X)(HLB of X) + (quantity of surfactant Y)(HLB of Y)]

                                                      (quantity of surfactant X+Y)

Apparatus

•  8 test tubes

• 1 of 50ml measuring cylinder

•   2 sets of pasture pipette and droppers

• Vortex mixer tool

•  Weighing boat

• 1 set of pestle and mortar

• Light microscope

•  Microscope slides

• 1 set of 5ml pipette and bulb

•  1 beaker of 50ml

•    Centrifuge tube of 15ml

•   Centrifuge

•   Coulter counter

•   Viscometer

•  Refrigerator (4degC)

       Materials

•  Water bath (45degC)

•  Palm oil

• Arachis oil

• Olive oil

• Mineral oil

• Distilled water

•  Span 20

• Tween 80

•  Sudan solution III (0.5%)

•   Isotonic solution III

Procedure

1. Each test tube was labelled and one straight line was drawn 1cm from the end of the test tubes

2. 4ml oil and 4ml of distilled water were mixed in the test tubes

3. Span 20 and Tween 80 were dropped in the mixture. Test tubes were closed and mixed with Vortex      mixer tool for 45 seconds. Time required to interface reached 1cm was recorded. HLB value was   determined for each sample.

4. Few drops of Sudan solution III were dropped to 1g of emulsion formed in the weighing boat and smoothen. Emulsion was parsed and colour of the sample was differentiated. Sample was smoothed above the microscope slide and was looked under the light microscope. Shape and size of globule formed was drawn and compared.

5. An emulsion of Mineral Oil was formulated (50g) using wet gum method.

6. 40g of emulsion formed was inserted into beaker of 50ml and homogenisation took place for 2 minutes using homogeniser.

7. 2g of emulsion formed was took before and after homogenisation into weighing boat and labelled. Few drops of Sudan solution III were dropped and smoothen. Emulsion was parsed and the texture, consistency, degree of oil characteristics and colour were compared under the light microscope.

8. Viscosity of emulsion 15g in 50ml beaker was determined after homogenisation using viscometer collaborated with “Spindle” type LV-4. Sample was later introduced to temperature of 45degC water bath for 30 minutes then at 4degC refrigerator for 30 minutes. Viscosity of emulsion was determined once the temperature reached room temperature for 10-15 minutes.

9. 5g emulsion was inserted into Centrifuge tube after homogenisation and was centrifuged 
(4500rpm, 10 minutes, 25degC). Interface height was measured and ratio of height separation was determined.

Result

Emulsion Result :

TUBE NO.	1	2	3	4	5	6	7	8
TWEEN 80	3	6	9	9	15	18	15	0
SPAN 20	15	12	12	6	6	3	0	0
HLB VALUE	9.67	10.73	11.34	12.44	13.17	14.09	15.00	0.00
STABILITY	Stable	Stable	Not Stable	Not Stable	Not Stable	Not Stable	Not Stable	Not Stable
COLOR	Light Red	Light red	More darker red than sample 4	Light orange	Light orange	Light orange	Light orange like sample 6	Dark Orange
VISCOSITY	Very viscous	More viscous than sample 3-8	More Viscous	More viscous	Less  viscous	Less viscous than sample 7,8	Less viscous	Less viscous ≥ sample 6,7
BUBBLE FORM	Yes but only few.	Yes but only very  few, small bubbles	Yes but less than sample 1,2	Yes but very lack of bubbles form	No only fine solution	Yes,Form a few and very fine bubbles.Its soluble solution.	Yes, but more even shape bubble.	Yes, flocculate and even shape.
TIME	1 minute 23 sec	1 minute 14 sec	1 minute 8 sec	46 sec	60 sec	23 sec	21 sec	19 sec

Particle under Micoscopic Examination

Reading	Viscosity (cP)			(Average ± SD)
	1	2	3
Before heat exposure	810	840	840	830 ± 17.32
After heat exposure	960	570	570	700 ± 225.17
Difference of viscosity (%) (Average ± SD)	16.99

Reading	Viscosity (cP)			(Average ± SD)
	1	2	3
Before heat exposure	1650	1800	630	1360 ± 636.63
After heat exposure	1170	1110	1260	1180 ± 75.50
Difference of viscosity (%) (Average ± SD)	14.17

Reading	Viscosity (cP)			(Average ± SD)
	1	2	3
Before heat exposure	4998	4998	4998	4998 ± 0
After heat exposure	850	800	850	833.33 ± 142.84
Difference of viscosity (%) (Average ± SD)	142.84

Reading	Viscosity (cP)			(Average ± SD)
	1	2	3
Before heat exposure	3300	3270	3300	3290 ± 17.32
After heat exposure	14520	12480	12030	13010 ± 1326.91
Difference of viscosity (%) (Average ± SD)	119.26

Amount of mineral oil (ml)	Average Viscosity (cP) (Average ± SD)		Difference of viscosity (%) (Average ± SD)
	Before heat exposure	After heat exposure
20	830 ± 17.32	700 ± 225.17	16.99
25	1360 ± 636.63	1180 ± 75.50	14.17
30	4998 ± 0	833.33 ± 142.84	142.84
35	3290± 17.32	13010 ±1326.91	119.26

(i) The graph of average viscosity before and after heat exposure versus volume of different mineral oil content (mL)

Group 2A = 20ML	Height(cm)
Separation phase	2.6
Initial emulsion	4.6
Height ratio	2.6 : 4.6 =0.57

Mineral oil (ml)	Seperation phase ratio
20	0.57
25	0.54
30	0.21
35	0.24

Tube No1.

Tube No 2

Tube No.3

Tube No.4

Tube No.5

Tube No. 6

Tube No. 7

Tube No 8

Calculation for Mineral Oil

For 20 mL mineral oil:

Average of viscosity before heat exposure : (810 + 840 + 840)/3 = 830

Average of viscosity after heat exposure : (960 + 570 + 570)/3 = 700

To calculate the standard deviation, SD of the sample, the formula is:

SD before heat exposure = √((810-830) ² +(840-830) ² +(840-830) ² )/3-1

                                            =17.32

SD after heat exposure = √((960-700) ² +(570-700) ² +(570-700) ² )/3-1

                                        = 225.17

Difference of viscosity (%) = (830-700)/((830+700)/2) x 100

                                          = 16.99%

Discussion

      1.What are the HLB values that produce a stable emulsion? Discuss

HLB values of 9.67 and 10.73 would produce a stable emulsion. These two values of HLB represent the intermediate value or properties between hydrophilic properties and lipophilic properties. It shows that for this emulsion, the HLB for both surfactants must be in between hydrophilic and lipophilic. 

2.Differentiate physical form of mineral oil emulsion that form and give comment.What is Sudan III test?Compare the separation of colour in emulsion that form and give your comment.

Size of bubbles in samples 1 with 15 drop of span 20 and 3 drop of tween 3 shows a very small , irregular, varies size and overlapping bubbles forms.It arranged compact and closely together compare other samples.

The size,distribution and arrangement of bubbles for all this 8 samples approximately same rather than samples of tube 2 and 8 which forms a very uneven distribution and the arrangement is far away from each other.So we can see a empty spaces between a bubbles under microscope.

Sudan III is a lysochrome (fat-soluble dye) diazo dye used for staining to color nonpolar substances like oils

Then, distribution of color from samples 1 till samples 8 from light red to darker orange because of decreasing amount of  span 20 and increasing in tween 80 which effect completely the bubbles and color distribution.

3. Based on the result :

Viscosity is defined by the measure of internal friction in a liquid or its resistance to flow. In this experiment, the oil that we used is mineral oil. We used different volume of mineral oil, which are 20mL, 25mL, 30mL and 35mL. In the experiment, the emulsion is heated in water bath at 45°C for 30 minutes and it is put into the refrigerator at 4°C for 30 minutes to lower its temperature. The exaggeration of temperature fluctuations subjected to the emulsion is used to compare the physical instabilities of the emulsion under normal stored condition. It is because when the emulsion is heated and then frozen, small ice crystals will be formed continually. This will disrupts the adsorbed layer of the emulsifying agent at the oil-water interface. As a result, we can quicken the time for the weakness in the structure to become more apparent for analysis.

From the graph above, as the volume of mineral oil increase, the viscosity of emulsion also increase. But for mineral oil content of 30mL, the viscosity deviates slightly from the theoretical graph. This might due to some human errors when we conduct the experiment.

Theoretically, the formation of ice crystal leads to the decrease in the viscosity of the emulsion. As the consequence, the sample viscosity before temperature cycling is actually higher than that of after temperature cycling. Besides that, the drop in the sample viscosity of the mineral oil after temperature cycling may be due to the occurrence of phase inversion. This means that the initially o/w emulsion is now converted into w/o emulsion. However, the graph obtained does not follow the pattern theoretically. For mineral oil of 35 mL, the viscosity of the emulsion is higher after heat exposure. This is due to the errors while conducting the experiment, for example we did not really wait for the emulsion to return to room temperature, but instead we directly measure the viscosity of emulsion when it almost reaches room temperature. The temperature of emulsion is too low after taking out from refrigerator. This caused the viscosity of emulsion to increase.

(ii) The graph of viscosity difference (%) vs volume of difference mineral oil content (mL)

Based on the graph, the viscosity differences before and after the temperature cycle among each sample shows a clear different percentage which are 16.99%, 14.17%, 142.84% and 119.26% for 20 mL, 25 mL, 30 mL and 35 mL of mineral oil respectively. Large viscosity difference was seen in sample III with 30ml mineral oil. Theoritically, it shows that the emulsion of sample III are less stable and weak emulsion. As the volume of dispersed phase (oil phase) increases, the stability of the emulsion decreases and phase inversion may occur. The small viscosity differences seen in sample I and II indicate that the emulsion is quite stable and does not undergo phase inversion.

Based on the experiment, there was several precaution step that need to be taken in order to have a more accurate result. Firstly, the mineral oil emulsion must be stirred first before running the viscometer for each reading. Next, the viscometer spindle need to be rinse before a new emulsion is going to be examined. Besides, we must make sure that the we were truly understand on how to set up the viscometer machine so that the sample’s viscosity is being determined under the required condition.

4.Plot the graph of separation phase effect of homogenizer versus mineral oil content

The Graph slowly down as the content of mineral oil increase.Separation phase length decrease as mineral oil content increase.Mineral oil particle slowly depart because of higher molecular weight that might contribute to shorter separation ratio

5.  What is the function of each material used in the formulation of emulsion? How the uses of different materials content affect physical characteristic and stability of emulsion formulation?

     Acacia is hydrophilic colloids which stabilise an emulsion by forming thick multi molecular layers. They are highly resistant to film rupture although they do not decrease interface tension significantly. The film may form electrostatic barrier to droplet collision depending on pH.

     Mineral oil is used as an emollient, lubricant and solvent for other ingredients. Syrup is actually used as a vehicle for medicine and it is usually used as a flavour to mask unpleasant taste. Vanillin has many uses as a flavouring agent and as a fragrance in pharmaceuticals. Alcohol is commonly used as a preservative. Water is widely used as a raw material, ingredient, and solvent in the processing, formulation, and manufacture of pharmaceutical products, active pharmaceutical ingredients (APIs) and intermediates, compendial articles, and analytical reagents. Medicinal products are prepared extemporaneously or where preparations are reconstituted or diluted with water prior to use by pharmacist.

Conclusion

      Use of different material content affect physical characteristic and stability of emulsion formulation as different material have different function of application.As the volume of dispersed phase (oil phase) increases, the stability of the emulsion decreases and phase inversion may occur