Recent Advances in Analytical Techniques

The chiral analysis of some seized drugs is important for the administration of justice. The chapter reviews the current analytical methods that have been developed and employed in academic, industrial and forensic laboratories, for the enantiomeric identification and quantitation of some controlled substances, with the focus on methamphetamine and related compounds. Although some spectroscopic methods are discussed, separation techniques, including gas chromatography, high performance liquid chromatography, supercritical fluid chromatography and capillary electrophoresis, especially those coupled with mass spectroscopy, are examined in detail. Some important terms and mechanisms associated with chiral analysis are discussed.

Currently there is an increase search for microorganisms as a potential source of biofuels and other bioproducts with commercial interest. A way to reduce microbial cultivation costs consists of using low-cost feedstocks, such as lignocellulosic materials, industrial by-products, effluents and wastewaters to cultivate microbes which, in some cases, allow the simultaneous effluent biological treatment and the production of high value-added products. However, such feedstocks may contain, or their pre-treatment may release inhibitory compounds that affect microbial metabolism, thus the process efficiency. Multi-parameter flow cytometry (FC) is an advanced and powerful technique that has been used for bioprocess monitoring, showing many advantages over the conventional microbiological/analytical techniques that are still currently used in most laboratories for process control. This chapter will describe the cell stress response to the most known inhibitors present in low-cost feedstocks, emphasizing the advantages of using the at-line FC technique in these process monitoring.

In recent years, the requirements for separation and preconcentration procedures have undergone numerous changes. A general trend is not only to improve the analytical performance of microextraction techniques but also to endeavor to satisfy the requirements of green chemistry. As a result, new modified and derived methods have been developed. One of the most popular techniques that meet the expectations of analysts is a dispersive liquid-liquid microextraction (DLLME). Owing to its rapidity, low costs, simplicity of operation, high recovery, as well as low consumption of both organic or inorganic compounds the method has been widely accepted as a miniaturized sample preparation technique. Despite the advances mentioned, DLLME still requires expensive and hazardous organic solvents, the use of multistep procedures leading to high risk of analyte losses, and has low selectivity and sample clean-up efficiency. That is why much attention has been paid to the development of green activities such as replacing toxic organic solvents and automating extraction techniques. In this context, a new group of solvents namely ionic liquids (ILs) has been utilized in combination with micro extraction procedures. ILs as molten salts are made of cations and anions. The novelty in relation to ILs is their application as the new non-molecular class of solvents characterized by a low melting point temperature arbitrary fixed at or below 100°C, as opposed to inorganic salts which are solid with melting point well above 500°C (NaI, NaBr, NaCl, 661, 747, 801°C, respectively). The term IL covers inorganic as well as organic salts. The potential of ionic liquids is based on their unique properties such as a low melting point, a negligible vapor pressure, high thermal stability, a significant viscosity, miscibility with water and other solvents. The ionic liquids environment is very different from that of polar or non-polar organic solvents. Besides the non-molecular nature of ILs, the significant advantages are their non-measurable vapor pressure at room temperature and appreciable liquid ranges. The desired physical and chemical properties of ILs may be controlled by selecting cation/anion combination or by incorporating specific functional groups in the IL molecule. Consequently, combinations of a variety of cation and anions lead to a tremendous number of ionic liquids and that is why ILs are often referred to as designer solvents. The unique properties of ionic liquids raised growing interest of scientists and engineers regarding an application for these compounds for the extraction purposes. Ionic Liquids and Polymeric Ionic Liquids (PILs) have been used in a Single-Drop Microextraction (SDM), a Liquid-Phase Microextraction (LPM), a Solid-Phase Microextraction (SPME), a Dispersive Liquid-Liquid Microextraction (DLLME), a Hollow Fiber-Supported Liquid Membrane Extraction (HFSLME) and in a Solid Phase Extraction (SPE), till the present day. The chapter presents extensive theoretical and practical information on the possible application of ionic liquids in various separation micro extraction techniques. It was shown that ILs might be successfully used in chemistry, medicine, environmental research and in other areas where is a need for selective isolation and enrichment of analytes. A systematic review has also been performed involving utilization of ILs in DLLME for the determination of organic compounds and metals in a variety of samples. It has been presented that the DLLME method has been successfully applied for the extraction and determination of a broad spectrum of organic and inorganic analytes from a variety of samples such as environmental, water, food, cosmetics, and biological.

Electrospinning was patented in 1902. This technology is attracting considerable research attention as a result of increasing demand to nanoscience and nanotechnology. Nanofiber structures (from 10 nm to 100 nm or bigger) have been obtained from synthetic and natural polymers via electrospinning techniques. The resulted electrospun nanofibers are used in various areas such as public health, biotechnology, environmental engineering, textile, defense industry, and energy deposition. Among them, analytical applications have a great potential as a sorbent for chromatographic separations and a modifier of surfaces in electrochemistry or spectroscopy. In this chapter, electrospun nanofibers based separation and detection systems will be explained in detail.

An overview of neutron activation analysis (NAA) and some applications for this technique are provided. The fundamentals of the various methods of NAA (INAA, relative, k0, large sample, prompt gamma charge particles, cyclic, molecular and radiochemical NAA, gamma-gamma coincidence NAA) are discussed in order to describe the most important scientific and technical aspects. Several problems associated with the technique are pointed out and briefly discussed. Emphasis is laid on the advantages of this technique for the determination of trace elements in geological, biological and environmental samples as an alternative analytical technique where other methods would not be the best choice. The role of NAA in quality assurance and quality control is also described.

Enantioselective chromatography is yet well documented as a powerful technique for the enantioselective resolution of racemates. Such potency has been empowered by advances in chiral stationary phases (CSPs). Many polysaccharide derivatives has been utilized as CSP in enantioselective chromatography and several reviews have been prepared focusing on the commercially available CSPs. In this review, we shed some light on the use of non-commercial polysaccharides namely chitosan, glycogen, chitin, pectin and amylopectin and their derivatives as chiral selectors in enantioselective chromatography and alternative polysaccharides derivatives exhibiting better analytical ability than para-substituted derivatives of polysaccharides.

Design, synthesis and applications of cation and anion sensing selective Ru(II)- Polypyridyl complexes have attracted a considerable attention because of their multipurpose and promising biological insinuation. Ruthenium(II)-polypyridyl ligands such as 2,2-bipyridine (bpy), 1,10-phenanthroline (phen), and/ or ortho-phenanthroline etc. on reaction with Ru(II) forms Ru(II)-polypyridyl complexes which have various significant benefits like metal-to-ligand charge transfer based on excited visible light and emission intensity, high chemical and photochemical stabilities, high shifts in Stokes (particularly more than 150 nm), greater response efficiency, low cytotoxicity and good water solubility. Owing to the MLCT emission, Ru(II) polypyridyl complexes were mostly used as essential materials in electro-generated chemiluminescence analysis offers unique properties like high rigidity, selectivity and less sensitive to environment. The multifaceted nature of Ru(II) polypyridyl-complexes in sensing is found as electrochemical sensors, solid state sensors, amperometric sensors, and straightforward chemosensors. A methodical report of different Ru(II) polypyridylcomplex chromophores emphasizing fluorophore frame work has been thoroughly discussed in this chapter. The binding mechanism has been proposed precisely. Unlike other metal complexes, the versatility and uniqueness of Ru(II) polypyridyl-complexes as chemosensor is observed in sensing of less common analytes which are rarely detected according to the literature. Polypyridyl Ru(II)-complexes being covalently bonded with photo conducting polymer may also be used as photosensitizers.