Carbohydrate, detection

Carbohydrate detection is important for applications such as glucose monitors these are arguably one of the most successful and relevant biosensors. An interesting fluorescence recovery-type saccharide sensor based on the reactivity of carbohydrates with boronic acids was reported in 2002 [36]. Specifically, modification of the cationic viologen-linked boronic acid derivative 40 to a zwitterionic species 41 upon covalent and reversible reaction of boronic acid with monosaccharides (Scheme 1) can cause the dissociation of the ion-pair in-... 

Easley C, Jin LJ, Landers JP, Ferrance JP. Carbohydrate detection on microchips for clinical detection of galactosemia. J Chrom A 2003 in press. 

Fig. 6-8. Potential sequence at a Au working electrode for carbohydrate detection.

Several metal oxides (platinum, gold," nickel, copper, ) and cobalt phtalo-cyanine have been employed as surface bound mediators for carbohydrate detection. In a dc amperometric mode of operation detectors based on these mediators exhibit a significant loss of response with time and/or exposure to analyte. Various potential pulse programs have circumvented this stability problem, but at the expense of sensitivity and complexity of the instrumentation. Silver electrodes coated with electrogenerated silver oxide exhibit electrocatalytic activity with respect to carbohydrate oxidation. This paper describes our efforts to utilize an electrode as a carbohydrate detector in a dc amperometric mode. 

Direct UV detection is the most versatile detection method in CE and is implemented in every commercial CE system. Unfortunately, its use for carbohydrates detection is restricted because of their lack of conjugated p-electron systems and, consequently, the relatively low... 

Figure 8.12 Potential sequence at a gold potentials. The detector signal is the charge working electrode for carbohydrate detection, (measured in Coulomb) that results from inte-(a) Standard sequence with three different grating the oxidation current between 0.2 and potentials and (b) sequence with four different 0.4s.

The carbohydrate content of acid-hydrolyzed corn stover can be high. When used for carbohydrate detection, pulsed amperometry is very selective but usually too sensitive. However, there is a solution to this problem in using a different injection valve with only 0.4 pL internal injection loop to decrease the amount of undiluted sample loaded onto the separator column. In addition, a... 

Figure 2. SEC curves of the precipitated Organocell white spruce hemicellulose fraction (top) and after xylanase incubation (bottom). SEC TSK HW 40 (100 x 2.5 cm) and TSK HW 50 (100 x 2.5 cm) coupled in line. For mobile phase and carbohydrate detection see Fig. 1.

Nickel-implanted boron-doped diamond electrodes (Ni DIA) were fabricated in view of their application for carbohydrate detection. This electrode produced well-defined and reproducible... 

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