الفهرس | Only 14 pages are availabe for public view |
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 |