Derivatization trends in capillary electrophoresis

Abstract

This survey gives an overview of recent derivatization protocols, starting from 1996, in combination with capillary electrophoresis (CE). Derivatization is mainly used for enhancing the detection sensitivity of CE, especially in combination with laser-induced fluorescence. Derivatization procedures are classified in tables in pre-, on- and postcapillary arrangements and, more specifically, arranged into functional groups being derivatized. The amine and reducing ends of saccharides are reported most frequently, but examples are also given for derivatization of thiols, hydroxyl, carboxylic, and carbonyl groups, and inorganic ions. Other reasons for derivatization concern indirect chiral separations, enhancing electrospray characteristics, or incorporation of a suitable charge into the analytes. Special attention is paid to the increasing field of research using on-line precapillary derivatization with CE and microdialysis for in vivo monitoring of neurotransmitter concentrations. The on-capillary derivatization can be divided in several approaches, such as the at-inlet, zone-passing and throughout method. The postcapillary mode is represented by gap designs, and membrane reactors, but especially the combination of separation, derivatization and detection on a chip is a new emerging field of research. This review, which can be seen as a sequel to our earlier reported review covering the years 1991-1995, gives an impression of current derivatization applications and highlights new developments in this field.

Design and synthesis of a hydrophilic fluorescent derivatization reagent for carboxylic acids, 4‐N‐(4‐N‐aminoethyl)piperazino‐7‐nitro‐2,1,3‐benzoxadiazole (NBD‐PZ‐NH2), and its application to capillary electrophoresis with laser‐induced fluorescence detection

“…There are numerous fluorescent derivatization reagents for carboxylic acids for high-performance liquid chromatography (HPLC) and CE (Waterval et al, 2000;Mukherjee and Karnes, 1996;Ohkura et al, 1994;Toyo'oka, 1995). The reagents bearing positive or negative charge seem to be suitable for CE.…”

Biomedical applications of capillary electrophoresis with laser‐induced fluorescence detection

“…This technical improvement of the microdialysis and CE coupling requires very short derivatization periods. Therefore, it is critical to use derivatizing agents such as OPA [52][53][54] or NAD [39,55,56] to produce the fluorescent derivatives in reaction times as short as a minute. This it is not possible using FITC.…”

“…They can be injected directly into the analytical system, making the deproteination procedures unnecessary. To speed up the analysis and prevent losses of sample, the derivatization can be done coupling microdialysis on-line [39,52,53,55,56].…”

“…Besides, it is possible to enhance the signal in CE by using microchip channels for stacking [167,168]. More and better on-line derivatization systems are desirable for microdialysates analysis to prevent losses of sample and improve the detection [55,56]. There is interest in the future development and potential applications of the coupling of CE with the biosensor detection, which is based on miniaturized electrophoretic chambers, that yields short analysis times, provides automation of the sample handling and for which small sample volumes are required [169].…”

Quantitative analysis of thiols in consumer products on a microfluidic CE chip with fluorescence detection

“…The second is an increase in the sensitivity of detection. Many different labeling agents are known for the derivatization of thiols [22,23]. Ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonic (SBD-F, Fig.…”