Volume 37, Issue 3

Surface-active agents are organic compounds of amphiphilic nature. When the concentration of surfactants is higher than a certain value, the monomers adhere to form well-defined aggregates known as micelles. These micelles have been employed in flow injection analysis (FIA) for various purposes. In chemiluminescence-based FIA, micelles can improve sensitivity by changing the chemical structures of the reagents, facilitating intramicellar energy transfer, accelerating the reaction kinetics, or stabilizing the excited singlet states. Micelles can improve sensitivity in FIA/ultraviolet-visible by electrostatic or solubilization effects. In FIA/fluorescence, emission intensity is considerably enhanced in micellar media due to the protective environment that restricts nonemissive energy transfer processes. If FIA is coupled with flame atomic absorption, the signals are enhanced with surfactants due to the decreased surface tension that results in the generation of smaller droplets during the aspiration and nebulization processes. In addition, surfactants promote the enrichment of the analyte in the double layer at the air-water interface. The FIA/cloud point extraction technique is based on using surfactants as alternatives to organic solvents. This review discusses the different roles of micelles in FIA methods.

Eosin Y (EY) is an acidic xanthene dye which is mainly used in food stuff and biological staining. Various analytical methods have been reported for the utility of this dye in the quantitative determination of several pharmaceutical compounds, heavy metals in addition to some surfactants and proteins. Most of the applied methods were based on the formation of association complexes between eosin Y and the target analytes in buffered aqueous solutions. The present article represents a comprehensive review for the use of eosin Y as a probe in analytical chemistry.

Terahertz (THz) spectroscopy is a rapidly emerging technology in the field of analytical chemistry. THz spectroscopy shows substantial scientific potential given that numerous absorption and emission molecular lines of interest in the chemical sciences belong to this spectral region. This article focuses on the current research progress on the detection of harmful gases, pesticides, antibiotics, toxic chemical compounds, and drugs of abuse by THz spectroscopy. The article also analyzes the key factors used for the detection of toxic chemical compounds by THz spectroscopy.