CONTENTS & ABSTRACTS
InEnglish. Summaries in Estonian
Proceedings of the Estonian Academy of Sciences.
Chemistry
Volume 53 No. 1March 2004
Special issue on capillary electrophoresis
Capillaryelectrophoresis in contemporary analytical chemistry; 3–5
Mihkel Kaljurand
Flow sampling in capillary electrophoresis witha pneumatically driven computerized sampler; 6–20
Arkadi Ebber, Sille Ehala,Marina Kudrjashova, Maria Kulp, Merike Vaher, and Mihkel Kaljurand
Abstract. Developments in sampleintroduction from liquid flow in capillary electrophoresis are reviewed. Wehave focused on the description of a pneumatically driven sampler that enablesto force the sample stream to pass the inlet of the separation capillary. Theadvantages of such an input device are absence of a voltage rise and/or droptime during sampling, ease of operation because no vial manipulations areinvolved, and simple automation and computerization. However, the mainadvantage of such input devices seems to be that they facilitate easy, multipleinputs from a single sample vial. This opens the possibility of monitoring theconcentration changes taking place inside the vessel, which is an importanttask in analytical biotechnology. This article describes some possibleapplications of such samplers in coupling capillary electrophoresis with flowinjection analysis and high performance liquid chromatography in multiple inputexperiments (with or without stacking) for the reduction of detection limitsand for monitoring reaction kinetics.
Key words: capillaryelectrophoresis, sample introduction, computerization, bioprocess monitoring,detection limits.
Separationof polyphenols and L-ascorbic acid and investigation of their antioxidantactivity by capillary electrophoresis; 21–35
Sille Ehala, Merike Vaher, and Mihkel Kaljurand
Abstract. Growing evidence of the role of free radicals and antioxidantsin health and ageing has focused great interest on these compounds. Vitamins Cand E and various carotenoids are known to act as strong antioxidants. Inrecent years however interest in various polyphenols as antioxidants has alsoincreased. Capillary electrophoresis, an effective analytical method, was usedto separate the standard mixture of polyphenols and to determine thepolyphenolic content of black currant qualitatively. In addition the oxidationof polyphenols and L-ascorbic acid with hydrogen peroxide (H2O2)was investigated. The experiment was performed with an in-house built reactorcoupled to a capillary electrophoresis system.
Key words: capillary electrophoresis, polyphenols, antioxidativeactivity, free radical scavenging assay.
Electrophoreticmobilities in nonaqueos capillary electrophoresis; 36–45
Merike Vaher and Mihkel Koel
Abstract. In nonaqueous capillary zone electrophoresis separation is based onthe interactions between the analytes and the ionic additive present in theseparation medium. The choice of thesolvents and solvent mixtures can influence the acid–base behaviour and solvationof the analytes and the additives; in addition, it can influence theelectroosmotic flow of the separation medium and the intrinsic mobility of theanalytes. Large changes in the separation factor and/or resolution, analysistime, and selectivity can be achieved by varying the type and content of theorganic solvent in the medium. A simple and reproducible method in the case ofwhich 1-alkyl-3-methylimidazolium based organic salts are used as additives inthe separation medium is suggested. Complexes are formed with the anionic partof the ionic liquid additive. This is the case with Br¸nsted acids and phenoliccompounds.
Key words: nonaqueouselectrophoresis, ionic liquids, 1-alkyl-3-methylimidazolium salts.
Instructionsto authors; 46–48
