Reference

Indirect UV detection of carbohydrates in capillary zone electrophoresis

Indirect UV detection of carbohydrates in capillary zone electrophoresis. Vorndran, A. E.; Oefner, P. J.; Scherz, H.; Bonn, G. K. (Inst. Radiochem., Univ. Innsbruck, Innsbruck 6020, Austria). Chromatographia, 33(3-4), 163-8 (English) 1992. CODEN: CHRGB7. ISSN: 0009-5893. DOCUMENT TYPE: Journal CA Section: 80 (Organic Analytical Chemistry) Section cross-reference(s): 44 A new system for the rapid and sensitive anal. for underivatized carbohydrates has been established using capillary zone electrophoresis with indirect UV detection. At an applied potential of 28 kV, sugars and sugar acids could be sepd. by the combined effects of electroendosmosis and electrophoresis within 20 min in a fused silica capillary of 50 mm internal diam. and an effective length of 100 cm using 6 mM sorbic acid, pH 12.1, as both carrier electrolyte and chromophore. The alk. pH ensured ionization of the sugars and, hence, their detection by means of charge displacement. Furthermore, the chosen concn. of sorbic acid allowed the smallest fractional change in the background signal to be measured. While the electrophoretic mobilities of the sugars were found to increase within a pH range of 11.9 to 12.3, those of the sugar acids were not affected. Due to the increasing competition of hydroxide ions in the displacement of the chromophore with rising pH, a significant loss of sensitivity is obsd. at pH values higher than 12.1 and this pH was found to provide sufficient resoln., optimum sensitivity, and an acceptably short anal. time. 576-36-3 and 512-69-6 are just another two chemicals used in this study. Under these conditions, a lower detection limit of 2 pmol was obtained for glucose. .