Palm oil esters are high molecular weight esters oil that has been newly synthesized by University Putra Malaysia researchers. It has received a lot of attention for its pharmaceutical and chemical application. The aim of this study is to study the effects of the palm oil esters with different HLB surfactant mixture on the ternary diagrams behaviour and to confine the various systems resulted from these combinations. These systems include traditional emulsion, gel area, transpernat micro-emulsion area, O/W and W/O emulsions. In this study, pseudoternary phase diagrams of water, POEs and non-ionic surfactant mixture of several HLB values were constructed using water titration method. The resultant mixtures collected after each addition and mixing of water were analysed visually, along with conductivity, dilution in water and dye test (methylene blue) to classify them as O/W emulsion (transparent and opaque) or W/O (opaque) and liquid or gel. As a conclusion, palm oil esters were found to be suitable for the formulation of different types of emulsion. Additionally, different HLB value of non-ionic surfactant(s) exhibited different pseudoternary phase diagram characteristics.Keywords: palm oil esters, Tween, Span, Pseudoternary phase diagram, O/W emulsio

Abdulkarim, Muthanna F.

Abdullah, Ghassan Z.

Ameer, Omar Z.

Basri, Mahiran

Chitneni, Mallikarjun

Mahdi, Elrashid S.

Noor, Azmin M.

Sakeena, M.H.F.

Salman, Ibrahim M

Sattar, Munavvar A.

Yam, Mun F.

English

International Journal of Drug Delivery

International Journal of Drug Delivery 3 (2011) 95-100 
http://www.arjournals.org/ijdd.html 
 
Research Article 
                                                            
Study of Pseudoternary Phase Diagram Behaviour and the Effect of 
Several Tweens and Spans on Palm Oil Esters Characteristics 
ISSN: 0975-0215 
 
Muthanna F. Abdulkarim1*, Ghassan Z. Abdullah1,  M.H.F. Sakeena1  ,Mallikarjun Chitneni1, Mun F. 
Yam1,2, Elrashid S. Mahdi1,  Ibrahim M. Salman1, Omar Z. Ameer1, Munavvar A. Sattar1, Mahiran 
Basri3, Azmin M. Noor1 
 
*Corresponding author: 
Muthanna F. Abdulkarim 
1. School of Pharmaceutical 
Sciences, Universiti Sains 
Malaysia, 11800 Minden, Pulau 
Penang, Malaysia. 
TEL: +60164849551; 
Email: 
muthana_albuldawy(at)yahoo.com 
2. Department of Chemistry, 
Faculty of Science, Universiti Putra 
Malaysia, 43400, Serdang, 
Selangor, Malaysia. 
3. Faculty of Science, Universiti 
Putra Malaysia, 43400 Serdang, 
Selangor, Malaysia 
 
 
 
 
 
 
 
Abstract 
Palm oil esters are high molecular weight esters oil that has been 
newly synthesized by University Putra Malaysia researchers. It 
has received a lot of attention for its pharmaceutical and chemical 
application. The aim of this study is to study the effects of the 
palm oil esters with different HLB surfactant mixture on the 
ternary diagrams behaviour and to confine the various systems 
resulted from these combinations. These systems include 
traditional emulsion, gel area, transpernat micro-emulsion area, 
O/W and W/O emulsions. In this study, pseudoternary phase 
diagrams of water, POEs and non-ionic surfactant mixture of 
several HLB values were constructed using water titration 
method. The resultant mixtures collected after each addition and 
mixing of water were analysed visually, along with conductivity, 
dilution in water and dye test (methylene blue) to classify them as 
O/W emulsion (transparent and opaque) or W/O (opaque) and 
liquid or gel. As a conclusion, palm oil esters were found to be 
suitable for the formulation of different types of emulsion. 
Additionally, different HLB value of non-ionic surfactant(s) 
exhibited different pseudoternary phase diagram characteristics.  
 
Keywords: palm oil esters, Tween, Span, Pseudoternary phase 
diagram, O/W emulsion 
 
Introduction 
Palm oil esters (POEs) are constituent of a 
modified form of Palm olein oil known simply as 
palm oil. It is a main and important agriculture 
commodity of which received great attention 
from researchers especially Malaysian 
researchers. Palm oil is a derivative of the fruit of 
the palm tree Elaesis guineenis that is constituted 
from even carbon numbers fatty acids [1,2]. 
Structurally, palm oil is a mixture of triglyceride  
 
 
compounds. Palm oil is edible oil and is used 
through out the world as main ingredient in many 
food products. Palm oil, as a raw material, had 
also attracted many researchers to study its use in 
topical delivery products and in the effort to 
synthesize new derivatives with beneficial 
properties for chemical and pharmaceutical 
applications. Universiti Putra Malaysia (UPM) 
had led the way  in the production of new 
doi:10.5138/ ijdd.2010.0975.0215.03058 
©arjournals.org,  All  rights reserved. 
Abdulkarim et al. International Journal of Drug Delivery 3 (2011) 95-100 
 
 
 
96
derivatives of palm oil [3]. Palm oil had been 
discovered to react with oleyl alcohol and the 
reaction was catalysed by the use of lipase 
enzyme to produce POEs contained high 
molecular weight esters of alcohol with an even 
number of carbon ranging from 12-32 [4].  
It was found that POEs has skin hydration 
activity of 40.7% after 90 minutes of its 
application [2]. The emollient effect of POEs had 
been proven thereby making this oil highly 
recommendable for its incorporation into the 
topical preparation as oil phase.  
Generally, emulsion, micro or nano-emulsion are 
dispersed systems of different ratios of oil, 
surfactant(s) and aqueous phase. Pseudoternary 
phase diagrams can be used to show the influence 
of changes in the volume fractions of the 
different phases on the phase behavior of the 
system. Micro or nano-emulsions are clear, 
stable, isotropic liquid mixtures of oil, water and 
surfactant, frequently in combination with a 
cosurfactant. The region or composition of micro-
emulsion is usually defined or identified by 
constructing ternary-phase diagrams.  In this 
study, we undertook the project in collaboration 
with Basri M et al of Universiti Putra Malaysia to 
study the effect of different non-ionic surfactants 
with different HLB values on pseudoternary 
diagrams of palm oil esters and water as external 
phase. 
 
Materials and Methods 
Materials 
Palm oil ester was a gift from UPM. Tween 80, 
Tween 85, Span 20, Span 85 and sodium 
benzoate were purchased from Sigma-Aldrich 
(USA). 
 
Method 
The study achieved with the assessment of POEs 
for use as the emulsion´s oil phase by 
constructing various pseudoternary phase 
diagrams of oil phase, water and surfactant of 
different HLB values by using water titration 
method. Mixtures of oil and surfactant(s) were 
prepared at ratios of 9.5:0.5 to 0.5:9.5 and 0:10 in 
separate containers. Distilled water (DW) was 
added in amounts equal to 5% w/w of the initial 
of the mixture into each container, followed by 
mixing for 5 min. After each addition and mixing 
of water, 0.5 gm of the resultant mixture was 
removed for analysis purpose and 0.5gm of (DW) 
was added to the remaining mixture in the 
container and mixed untill reaching the maximum 
water content (the amount of oil phase in the 
mixture is almost 0%). 
The types of emulsions formed were confirmed 
by electrical conductivity and microscopic 
examination of emulsion stained with methylene 
blue which is known as the water soluble dye 
method.  The visual qualities of the mixtures 
were noted as opaque or transparent fluid or as 
viscous cream. Gel was physically identified as 
the formulae that do not flow if the container is 
tilted at 90°.  To facilitate the accurate evaluation 
of the mixtures physical state, air bubbles were 
cleared by sonication method.  All the mixtures 
forming O/W transparent systems were marketed 
and plotted onto the triangle graph as the O/W 
micro-emulsion area. Similarly, all other mixtures 
of W/O (opaque), O/W (opaque) and gel were 
marketed and plotted to represent the three 
respective areas in the ternary phase diagram. 
Six pseudo-ternary phase diagrams were 
constructed each representing the phase diagram 
of water, oil and surfactant or it´s mixture having 
specified HLB value. HLB 15 pseudo-ternary 
phase diagram was constructed by using Tween 
80 as the emulsifier. HLB 11 pseudo-ternary 
diagram was constructed using Tween 85 as 
single emulsifier. Mixtures of Tween 80 and 
Span 20 in ratios of (80:20), (53:47) and 
(6.25:93.5) were used to construct ternary phase 
diagrams of mixtures containing the emulsifier 
having HLB values of 13.72, 12 and 9 
respectively.  Additionally, a mixture of Tween 
80 and Span 85 in a ratio of 77:23 was used to 
construct the phase diagram of mixture 
containing HLB 12 emulsifier. 
 
Results and Discussion 
The mixing of oil, water and surfactant in 
different ratio, can produce different types and 
Abdulkarim et al. International Journal of Drug Delivery 3 (2011) 95-100 
 
structures of emulsion and micro-emulsion 
systems. They depend on the chemical nature, 
molecular structure and concentration of 
surfactant and other ingredients. Surfactant type 
plays a major role in determining the rheological 
properties and droplets size of the systems [5]. 
Similarly, oil type whether it is triglyceride form 
or long chain hydrocarbon can change the 
physical properties of the systems. Oil can affect 
the interfacial tension and surface pressure as 
well as the stability of the system [6, 7]. 
This study is concerned with the evaluation of 
palm oil ester as the internal phase of O/W cream 
for topical application. The rheological properties 
and types of emulsion, micro-emulsion and gel 
produced by mixture of POEs, water and 
surfactant at various HLB values were assessed to 
select the promising O/W cream formulae. Those 
exist as gel formulae were the preferable ones as 
they are semisolid preparations and are suitable 
for topical applications. Surfactants present at 
certain percentage have the ability to build the gel 
structure within the emulsion system without 
addition of any polymer or thickening agent [8].  
POEs is a modified long chains esters of palm oil 
triglyceride which is safe for normal 
consumption. Non-ionic surfactants in general 
and Tween and Span in particular are safe agents 
for all biological tissue in general and for skin in 
specific [9, 10]. These non-ionic emulsifiers are 
compatible with various ingredients used in the 
preparation of emulsions and are not affected by 
pH. They supposed to have an enhancement 
effect on the skin barrier [11]. Combination of 
lipophilic and hydrophilic non ionic surfactants is 
able to build highly structured emulsion [12, 13].   
Different combinations of oil, surfactants and 
water when mixed together produce either 
traditional emulsion or micro-emulsion in the 
form of O/W or W/O. Bicontinuous system can 
also be formed in case of micro-emulsion system 
where each phase of water and oil is found as a 
continuous phase [14].  
Construction of pseudoternary phase diagrams is 
the best way to study all types of formulations 
that can originate from mixing of surfactants, 
water and oil and these diagrams can cover the 
whole probabilities of mixing ratios. Fig.s 1.1 to 
1.6 are phase diagrams of mixtures of POEs, 
water and surfactant or its mixture of HLB 15, 
13.72, 12, 12, 11 and 9 respectively. All figures 
showed the presence of a transparent micro-
emulsion area with the exception of Fig. 1.6 
representing the diagram for mixture of oil, water 
and surfactant mixture of HLB 9. The transparent 
micro-emulsion areas were found to be attached 
to the margins of diagrams where water or oil 
ratios are low and the surfactant ratio is high. 
From conductivity measurements, it can be found 
that each point in the transparent micro-emulsion 
areas was able to conduct electricity and when 
tested with agent methylene blue solution, it was 
found to have a blue background of methylene 
blue with oil droplets dispersed in it, indicating 
that the system is O/W micro-emulsion. 
Formation of micro-emulsion system by using 
nonionic surfactant or mixture of nonionic 
surfactants, were reported by many researchers 
[15, 16]. 
Pseudoternary phase diagram produced from 
mixtures containing surfactant of HLB 9 showed 
no transparent O/W micro-emulsion area and no 
gel area. On the other hand, it exhibited the 
biggest W/O area. The absence of transparent 
 
DW POEs 
HLB 15 
Tween 80 
█ Transparent O/W liquid emulsion    
█ Non-Transparent W/O Liquid emulsion   
█ Non-Transparent O/W Liquid emulsion 
█ Viscous area 
█ Transparent gel                          
 
Fig 1.1 
 
 
97
Abdulkarim et al. International Journal of Drug Delivery 3 (2011) 95-100 
 
O/W micro-emulsion might reflect the 
insufficient association of the mixed surfactants 
at the interface [17]. In this case, the amount of 
Tween 80 might not be enough to form a mixed 
surfactants layer at the interface that is 
responsible for producing the micro-emulsion 
system. The phase diagrams obtained also 
showed that areas of W/O dispersions decreased 
as the HLB value of the surfactant system 
increased, reaching the smallest area at HLB 15. 
This is in accordance with the theory of HLB of 
surfactant which stated that surfactant used has 
more tendency to produce the emulsion type in 
which it is more soluble  in the external phase 
[18]. 
 
Tween 80:Span 20 (80:20) 
HLB 13 72
DW POEs █ Transparent O/W liquid emulsion    
█ Non-Transparent W/O Liquid emulsion   
█ Non-Transparent O/W Liquid emulsion 
█ Viscous area 
From Fig.s 1.1, 1.2, 1.3, 1.4 and 1.5, it is evident 
that gel area is formed when the water content in 
the system was in the range of 25 to 60%. It was 
found that water content below 25% is 
insufficient to hydrate the polyoxyethylene 
groups which are critical for the swelling of 
surfactant chains to demonstrate the gel structure. 
Accordingly, water content of more than 60% 
will increase the distance between the 
polyoyethylene groups an destabilize the gel 
structure leading to breaking of the swelled gel 
[19]. The phase diagrams for mixture containing 
surfactant HLB12, 13.72 and 15 as represented 
by Fig.s 1.1, 1.2 and 1.3, illustrate that increasing 
the concentration of surfactant results in stronger 
and more rigid gel-emulsion structure.  
Pseudoternary diagrams containing Tween 80 
alone and those containing mixtures of Tween 80 
(HLB 15) and Span 20 (HLB 8.6) exhibited 
higher gelly area compared to mixtures of Tween 
80 and Span 85 (HLB 3). The results showed that 
 
Fig 1.2 
 
Tween 80:Span 20 (53:47) 
HLB 12
DW POEs 
█ Transparent O/W liquid emulsion    
█ Non-Transparent W/O Liquid emulsion   
█ Non-Transparent O/W Liquid emulsion 
█ Viscous area 
 
Fig 1.3 
 
Tween 80:Span 85 
77:23 
HLB 12
DW POEs █ Transparent O/W liquid emulsion    
█ Non-Transparent W/O Liquid emulsion   
█ Non-Transparent O/W Liquid emulsion 
█ Viscous area 
 
Fig 1.4 
 
 
98
Abdulkarim et al. International Journal of Drug Delivery 3 (2011) 95-100 
 
at very low concentration of oil and high 
concentration of water and surfactants mixture, 
mixture of Tween 80 and Span 85 having HLB 
value of 12 formed smaller gel area than that of 
the mixture of Tween 80 and Span 20 having 
HLB value of 12.  Since the mixture of Tween 80 
and Span 85 formed a small viscous gel area, this 
surfactants combination was excluded from 
further study. The results obtained indicated that 
a mixture of two non-ionic surfactants with big 
difference in HLB values between them might 
not be able to produce stable preparations. This 
may be due to the fact that the majority of 
surfactant molecules with very low HLB value 
dissolved in the oil phase and the surfactant with 
high HLB value dissolved more  in the water [20] 
that enables them to function together well 
enough, thus exerting less synergistic effects than 
mixture of surfactants having closer HLB values. 
 
Tween 85 
HLB 11 
DW POEs 
█ Transparent O/W liquid emulsion    
█ Non-Transparent W/O Liquid emulsion   
█ Non-Transparent O/W Liquid emulsion 
█ Viscous area 
█ Transparent gel                          
Fig. 1.5 (HLB 11) containing Tween 85 alone as 
surfactant was constructed for comparison with 
Fig. 1.1 of HLB 15 containing Tween 80 alone. 
When Tween 85 was used, the gel area formed 
was smaller than when the surfactant was Tween 
80. Tween 85 with tri-oleate ester chains is 
expected to be more soluble in the internal oil 
phase. This would lead to insufficient numbers of 
polyoxyethylene chains available to form H-
bonds at the interface and the external phase [21]. 
These results indicated that Tween 80 would be a 
better surfactant than Tween 85 for formulating 
emulsions especially those with gel properties. 
 
Fig 1.5 
 
Tween 80:Span 20  
(6.25:93.75) 
HLB 9
DW POEs █ Non-Transparent W/O Liquid emulsion     
█ Non-Transparent O/W Liquid emulsion 
 
Fig. 1.6 
 
Acknowledgements 
The authors thank Institute of Post-graduate 
studies, Universiti Sains Malaysia and Bio-
pharmacy Co-operative Center, MOSTE for 
providing financial assistance. 
 
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Study of Pseudoternary Phase Diagram Behaviour and the Effect of Several Tweens and Spans on Palm Oil Esters Characteristics

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Study of Pseudoternary Phase Diagram Behaviour and the Effect of Several Tweens and Spans on Palm Oil Esters Characteristics

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