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Inductively Coupled Plasma Mass Spectrometry for Nanomaterial Analysis
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Francisco Laborda, Eduardo Bolea, Maria S. Jimenez
Electromigration separation techniques have demonstrated to be powerful analytical tools for the separation and characterization of ENMs (Trapiella-Alonso et al. 2016). CE, the most employed format of electromigration separations, provides a high-resolution separation of any type of compounds, based on their intrinsic properties such as the charge and the hydrodynamic diameter or the viscosity and temperature of the separation medium. CE employs narrow-bore capillaries, where species are separated due to their different electrophoretic mobility within an electroos-motic flow of an electrolyte solution under a high voltage (Ban et al. 2015). Capillary zone electrophoresis (CZE) is the simplest mode of CE, it is based on the use of separation media with relatively low viscosity where the species move from one end of the capillary to the other according to the balance between their electrophoretic mobility and the electroosmotic flow. Separations can be improved by adding specific additives to the separation medium, which are the base of other CE modes. In micellar electrokinetic chromatography (MEKC), a suitable charged surfactant, such as sodium dodecylsulfate, is added in a concentration sufficiently high to allow the formation of micelles, so that species are separated according to their different partition between the micelle, acting as a pseudostationary phase, and the separation medium. In capillary gel electrophoresis (CGE) the capillary is filled with a polymeric gel, the electroosmotic flow is eliminated and separation is based just on the electrophoretic mobility and size of the species. In capillary electrochromatography (CEC), the capillary is packed with microparticles coated with a bonded stationary phase and species are separate according to their partition between this stationary phase and the separation medium, which is moving as a result of the electroosmotic flow.
Impacts of several salts on the clouding development, nature of interactions and associated physico-chemical variables of mixture of promethazine hydrochloride and conventional nonionic surfactant
Published in Journal of Dispersion Science and Technology, 2023
Malik Abdul Rub, Md. Ruhul Amin, Sharifur Rahman, Abdullah M. Asiri, Mohammad Majibur Rahman, Md. Anamul Hoque, Maha Moteb Alotaibi, Mohammed Abdullah Khan
Surfactants are amphiphilic substances that can reduce surface tension and get dissolved in both organic and aqueous solvents; because of their versatile solubilities, surfactants have long been used in different research areas, like electrochemistry, surface chemistry, separation chemistry, engineering, and other branches of science.[1,2] Surfactants have numerous applications in pharmaceutical products, cosmetics, cleaning agents, as well as in recognizing organic fragments, metal species, and enzymes.[3–6] Surfactant micelles are largely employed in designing the simplified model of bio-membranes.[7] Also, surfactants are used to make many organic molecules soluble in water because they possess weakly polar character.[8–11] One of the most important applications of surfactant is in oil recovery.[12] In earlier times, it was difficult to separate the neutral molecules from complex mixtures, but recently, the separation of the neutral molecules through the micellar electrokinetic chromatography (MEKC) technique and the microfluidic technique with the help of surfactant micelle has been reported.[13] Surfactants are widely used in different chromatographic techniques with different phases, such as most often, they are used with the stationary phases, and, in other cases, they are used with the mobile phase to make the separation process easier. There are many molecular species which do not like to enter the mobile phase, where micelles help those substances to be eluted in the mobile phase and help to separate them from the complex mixture.[13]
Au-doped nanostructured TiO2/C material derived from MIL-125 as a highly sensitive electrochemical sensor for ferulic acid
Published in Journal of Coordination Chemistry, 2023
Gaihua Li, Shuang Liu, Yanjun Liu, Xiaoyu Pang, Miao Li, Yachang Gong, Yao Wu, Xinjie Guo
Ferulic acid (3-methoxy-4-hydroxy cinnamic acid) is a bioactive phenolic component widely found in complex matrices such as vegetables, flowers, fruits, bamboo shoots, packed fruit juice drinks, alcoholic beverages, olive oil and coffee. Moreover, it is one of the active ingredients in Chinese medicinal materials such as angelica sinensis, ligusticum wallichii, spina date seed and cimicifuga heracleifolia [1–3]. Ferulic acid has a wide range of physiological and medicinal effects and can be used as a photo-protective ingredient in skin care products to block UV irradiation and is known as an anti-aging, anti-diabetic, anti-inflammatory, anti-ulcer, anti-haemolytic, chemo-preventive and anti-viral agent and it is used as an anti-bacterial component in implants [4–8]. In recent years, ferulic acid has been used clinically used for coronary heart disease, cerebrovascular disease, vasculitis, cytopenia and thrombocytopenia and widely used in biomedicine, food additives and cosmetics because of its pharmacological activity [9]. Ferulic acid is also found as a trace waste water contaminant from the olive oil industry and needs to be detected as it is the cause for a potential ecological hazard, as reported [10]. The pungency of an alcoholic beverage such as beer and wine is directly related to the phenol content. For quick and sensitive determination of ferulic acid in the human body, food products, pharmaceutical compounds, beverages and effluents, various techniques have been used such as high-performance liquid chromatography, gas chromatography, thin layer chromatography, spectroscopy, chemiluminescence, micellar electrokinetic chromatography, UV-VIS, fluorescence, coulometric array detection and plasmon resonance light scattering [11–19]. However, these traditional detection methods are not suitable for routine clinical screening because of their complicated pretreatment processes, expensive equipment and solvent toxicities. Electrochemical techniques have become an alternative method for detection of ferulic acid on account of their rapid, reliable, high selectivity, low cost, and sensitive detection. Some of the working electrodes such as didodecyl dimethyl ammonium bromide/nafion composite film-modified carbon paste electrode [20], polypyrrole-multiwalled carbon nanotubes modified electrode [21], carbon nanotubes decorated with manganese dioxide nanoparticle modified electrode [22] and glassy carbon electrode modified with MWCNTs [23] have been used to quantitatively analyze the electrochemical behavior of ferulic acid. Yaping Ding et al. [24] studied the electrochemical behavior of ferulic acid using multi-walled carbon nanotube modified glassy carbon electrodes with detection limit of 1 × 10−7 M. Moreover, E. F. Newair et al. [21] reported ferulic acid determination using a carbon paste electrode modified with dodecyl dimethyl ammonium bromide/Nafion composite membrane. The detection limit of ferulic acid was 3.9 × 10−7 M. The limit of detection (LOD) of these methods is usually low enough to detect ferulic acid in real samples. According to previous work on electrochemical sensors, modified electrodes are limited due to the complicated preparation steps. Therefore, it is important to develop a convenient and cheap method for ferulic acid quantification.