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Thin-Layer Chromatography in Food Analysis
Published in Bernard Fried, Joseph Sherma, Practical Thin-Layer Chromatography, 2017
Derivatization refers to any process by which a compound is converted to a different chemical compound. It can be achieved by introducing chromophores or fluorophores into the molecules of the compounds to be determined. The purposes of the derivatization are to increase the stability of the sample and to improve the sensitivity and selectivity of detection. Depending on the moment of derivatization in the total procedure, pre- and postchromatographic derivatization can be distinguished. Derivatization reagents can be applied by means of spraying or dipping, but spraying is probably the preferred method.48 Corrosive spray reagents can be used to char, in an oven, most nonvolatile organic substances on inorganic layers.50 The consecutive application of two or more detection reagents on one chromatoplate increases the probability that no fraction remains undetected.50 Derivatization prior to TLC can increase resolution as well as sensitivity of detection.19,48
Sample Preparation Methods for Determination of Pollutants in Air Samples
Published in Leo M. L. Nollet, Dimitra A. Lambropoulou, Chromatographic Analysis of the Environment, 2017
Francisco Pena-Pereira, Jacek Namieśnik
Derivatization is commonly employed in analytical chemistry with the aim of improving the isolation, separation, and detection of target compounds. A wide variety of derivatization reactions have been reported in the literature aiming at enhancing the sensitivity, selectivity, extraction efficiency, stability of analytes, and overall quality of the data (Rosenfeld, 2003). It should be highlighted, however, that derivatization reactions can give rise to the formation of unexpected derivatives or by-products that can disturb the chromatogram (Little, 1999). In addition, they can involve the use of toxic and harmful reagents; contribute to the generation of wastes; and be laborious, tedious, and time consuming. For all these reasons, derivatization has been identified as an extra step of analytical procedures that should preferably be avoided. In fact, the eighth principle of green chemistry specifically recommends avoiding derivatization reactions whenever possible (Keith et al., 2007). Nevertheless, certain microreactions can offer significant opportunities for the application of a given sample preparation technique and can be valuable strategies to attain the abovementioned objectives (Lavilla et al., 2014). A highly recommended special issue, “Microreactions in Separation Science,” has been recently published by the Journal of Chromatography A (Poole, 2013).
Reduce Derivatives
Published in Aidé Sáenz-Galindo, Adali Oliva Castañeda-Facio, Raúl Rodríguez-Herrera, Green Chemistry and Applications, 2020
Revathi Kottappara, Shajesh Palantavida, Baiju Kizhakkekilikoodayil Vijayan
One of the key principles of green chemistry is to reduce or avoid derivatization in a chemical reaction. Derivatization necessitates the use of extra energy and reagents and will lead to extra waste generation in the synthesis. It also includes the use of protecting or deprotecting agents and any short term modification of the physical and chemical process. Blocking, protection and deprotection of functional groups has been part of standard organic synthetic methodology for decades and has made feasible the synthesis of numerous complex molecules. But this approach comes at a price, added synthetic steps, possible decrease in yield and a reduction in the atom economy of the process.
Soot differentiation by laser derivatization
Published in Aerosol Science and Technology, 2019
Madhu Singh, Chethan K. Gaddam, Joseph P. Abrahamson, Randy L. Vander Wal
A solution may be found in the related field of analytical chemistry, wherein it is often necessary to derivatize analytes to make detection possible (Rosenfeld 2003). Derivatization is the process of chemically changing a compound and producing a new compound with properties agreeable with a specific analytical method. Unconsidered to-date is the process of derivatization by pulsed laser annealing as applied to combustion produced soots. Traditional thermal annealing over long heat treatment times has been used since the early 1800s to study the structural transformation of carbon when subject to high-temperature heat treatment (Abrahamson et al. 2017). However, given the long heating time-scales, this has been used to analyze structural transformations thermodynamically, rather than kinetically. Laser derivatization is used here in a similar manner to bring out minor dissimilarities in nanostructure and seemingly subtle differences in chemistry upon laser heating. Contributing to these changes are small changes in initial nanostructure and composition that become magnified by the fast heating and rapid quenching. This has been recently demonstrated on synthetic soot using oxygen and sulfur as heteroatoms and their subsequent diverging nanostructure upon pulsed laser annealing (Abrahamson and Vander Wal 2018) to potentially differentiate soot generated by fuels with varying sulfur content, for instance (Anderson et al. 2011; Huang and Vander Wal 2013).
Electrochemical-enhanced nanoscale oxygen-vacancy CuFe2O4 to activate persulfate (E/oxygen-vacancy CuFe2O4/PS) for separation of Ebselen from wastewater
Published in Environmental Technology, 2023
Zhenjun Wang, Liang Meng, Tianlie Luo
The intermediate and final products generated during the degradation of EBS-containing wastewater by oxygen-vacancy CuFe2O4-activated PS system are detected by GC-MS. Derivatization is used to pretreat samples, that is, chemical methods are used to convert difficult and unstable intermediates in the sample into compounds with similar structures, which are easy to separate and detect and stable. In the experiment, BSA was used as a derivatizing agent to pretreat the sample to replace the active H in the product, that is, –NH and –OH in the degradation product can be replaced by trimethylsiloxane.
Determination of gaseous formaldehyde by derivatization using magnetic multiwalled carbon nanotubes (MWCNTs) modified with 2,4-dinitrophenylhydrazine (DNPH) and high-performance liquid chromatography – ultraviolet detection (HPLC-UV)
Published in Instrumentation Science & Technology, 2022
Identifying optimal derivatization conditions is vital to guaranteeing reliable determination of formaldehyde in aqueous solution. Reaction parameters, such as pH, time, and the temperature of derivatization, were optimized. When one parameter was changed as a variable factor, other parameters were fixed at their optimized values. The recovery was measured by determining spiked formaldehyde in ultrapure water samples (0.5 mg/L).