Colloids and Surfaces A: Physicochem. Eng. Aspects 460 (2014) 321–326 Contents lists available at ScienceDirect Colloids and Surfaces A: Physicochemical and Engineering Aspects journa l h om epage: www.elsevier.com/locate/colsurfa Moderately stable emulsions produced by a double syringe method V. Nastasa a , K. Samaras b , M.L. Pascu a,∗ , T.D. Karapantsios b a National Institute for Laser Plasma and Radiation Physics, Bucharest, Romania b Aristotle University, Chemistry Department, Thessaloniki, Greece h i g h l i g h t s • Study of oily vitamin A in water solutions of Vancomycin emulsions generated by standard emulsifica- tion techniques and by a simple and transportable double syringe system (DSS). • The addition of different stabilizers (Xanthan gum, Tween 80, Nonaethy- lene glycol monododecyl ether, and Glycerine) in the examined range of concentrations has no strong effect on oil droplets dimensions in water. • The results show that the Tessari method (DSS) produces moderately stable emulsions in a cheap, easy to apply and affordable way. g r a p h i c a l a b s t r a c t a r t i c l e i n f o Article history: Received 18 November 2013 Received in revised form 9 January 2014 Accepted 17 January 2014 Available online 26 January 2014 Keywords: Emulsions Surfactants Double syringe system Tessari method Rheology a b s t r a c t Different emulsification techniques lead to emulsions with different targeted properties specific to their intended use. In this study, emulsions are generated using several emulsification techniques. They are compared as regards the component droplet size distribution and their stability in time. A particular technique based on the “Tessari” (known as double syringe system – DSS, as well) method – used originally for foam generation – is evaluated for emulsion production. Results show that DSS method leads to emulsions with mean droplet size about two orders of magnitude larger than in the case of emulsions obtained by conventional high speed and high pressure homogenizers (HPH). However, DSS emulsions have comparable viscosity behavior with the emulsions obtained by conventional methods and are stable for time intervals of a couple of hours which is convenient for specific medical applications. Furthermore, this study evaluates the effect of small quantities of some emulsion stabilizers on the mean droplet size distribution of emulsions. In the examined narrow range of values no significant modifications of the mean droplet size distribution was observed. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Emulsions are defined as heterogeneous systems of one liquid dispersed in another, in the form of droplets, with droplet sizes that range from nanometers up to 100 m. In particular conditions, emulsions may consist of oil droplets dispersed in a continuous ∗ Corresponding author. Tel.: +40 214575739. E-mail address: mihai.pascu@inflpr.ro (M.L. Pascu). water phase (oil-in-water) or of water droplets dispersed in a continuous oil phase (water-in-oil), at different oil/water ratios. Each droplet is coated with surfactant (emulsifier) molecules that are necessary for both satisfactory emulsification (achieving small droplets of the dispersed phase) and emulsion stability (slowing down phase separation) [1]. Usually, the two liquid phases are cho- sen to be fully immiscible and chemically non-reactive whereas their mixture is thermodynamically unstable [2]. When the two liq- uids are highly immiscible, the dispersed phase cannot exchange molecules with the continuous phase, and therefore the effect of 0927-7757/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.colsurfa.2014.01.044