الفهرس 
Surface Tension and Interfacial Tension Measurement
Electrochemical MethodsOnly 14 pages are availabe for public view
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Abstract
Surface active agents (surfactants) are substances with characteristic
amphipathic molecular structure. Micellization is the most important property
of surfactants. It enables their usages in detergency, emulsion stabilization,
drug-delivery vehicle, etc. The narrow concentration range of surfactant at
which micelles form is termed critical micellar concentration (CMC).
Surfactants are widely used in many fields such as industry, pharmaceutical
chemistry, synthetic chemistry, materials science, biochemistry, biology, and
analytical chemistry [1]. In addition to their various applications, some
surfactants may have pharmacological action.
The determination of surface-active drugs is challenging due to their
specific physical and chemical properties and the different physical
interactions that surfactants undergo in the solution. Besides, many of these
drugs do not possess any chromophores, they exhibit weak or no absorption
of electromagnetic radiation. Few methods were reported for the
determination of drugs that have surface activity, and most of them are
complicated methods [2]. Hence, there is a need for the development of a
simple method capable of their quantitative determination in pharmaceutical
dosage forms.
Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Tanta University
Abstract
II
CMC is an important parameter for each surfactant [3]. Determination
of the CMC of surfactants is crucial, because of their numerous applications
in analytical chemistry. Micelles have been employed in micellar
chromatography, micellar electrokinetic chromatography, flow injection
analysis, analytical extraction, spectroscopy, titrations, and electrochemistry
[4]. CMC can be determined by many different techniques and methods and
estimated by a plot of a certain physical property versus the surfactant
concentration [3]. Physical properties include the solution viscosity, density,
surface tension, interfacial tension, refractive index, and light scattering.
Spectrophotometric and fluorometric methods using dyes and other probes are
also used for the evaluation of CMC [5,6].
The work performed in this thesis was to develop new analytical
methods for the determination of the CMC of different types of surfactants,
e.g. ionic (cationic, anionic, and zwitterionic) and nonionic. Also, the
determination of a non-chromophoric drug with surface activity; polidocanol
(PD).
This thesis is composed of the preceding parts:
Part 1: Development of New Analytical Methods for Determination of
Critical Micelle Concentration
This part includes three chapters:
Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Tanta University
Abstract
III
Chapter 1: Review of Literature
This chapter presents a general introduction about surfactants,
micelles, CMC, and their importance. It discusses the principles, advantages,
limitations, and remarks for different techniques and methods that were
developed and used for the determination of the CMC of a variety of
surfactants.
Chapter 2: Curcumin as An Organic Probe in Determination of Critical
Micelle Concentration
In this chapter, curcumin was examined as a probe for the
determination of CMC of different surfactants, based on the principle of
tautomerism. Curcumin was proven to be a successful probe for spectroscopic
determination of CMC which can give accurate CMC values of the tested
surfactants.
Chapter 3: Metal Complexes as Inorganic Probes in Determination of
Critical Micelle Concentration
This chapter presents the theory and investigation of the use of colored
metal complexes; cobalt (II) thiocyanate and ferric salicylate as novel
spectroscopic probes to determine CMC values for some surfactants. Different
techniques were used to achieve a better comparison of the results