CONTENTS & ABSTRACTS
In English.Summaries in Estonian
Proceedings of the Estonian Academy of Sciences.
Chemistry
Volume 53 No. 2 June 2004
Capillary electrophoretic monitoring ofmicrobial growth: determination of organic acids; 51–64
Marina Kudrjashova, Heli Tahkoniemi, Kati Helmja,and Mihkel Kaljurand
Abstract. Capillaryelectrophoresis (CE) with indirect UV detection was used for determination oforganic acids produced by microorganisms in a liquid medium. The microbialculture broth has a complex composition including organic metabolites and alarge amount of mineral salts. Analysis of such samples is troublesome.However, in the benzoate background electrolyte with addition ofcetyltrimethylammonium bromide (CTAB), organic acids were successfully separatedwithout a significant peak distortion due to the matrix effect. Thiselectrolyte system was applied for a study of solubilization of mineralphosphates by rhizosphere fungi. It was demonstrated also that a backgroundelectrolyte containing pyridine-2,6-dicarboxylic acid as a complexing reagentand CTAB allows simultaneous determination of organic acids and metal cationsin one electrophoretic run. This electrolyte composition provides a basis formore sophisticated application of CE: monitoring the consumption of heavymetals by bacterial culture.
Speciation of chromium using wide-borecapillary electrophoresis with electrothermal atomic absorption spectrometrydetection; 65–74
Ruth Kuldvee, Aleksei Zaidentsal, Anu Viitak, MailiTreumann, and Mihkel Kaljurand
Abstract. The development of a newmethod for chromium speciation using capillary electrophoresis–electrothermalatomic absorption spectrometry (CE–ETAAS) is described. For that purpose asimple capillary electrophoresis device enabling simultaneous separation andconcentration of different chromium species has been designed andconstructed. The device proved suitable for separating Cr(III) and Cr(VI) inaqueous samples. The sample amounts were sufficient for off-line collection andsubsequent off-line detection with ETAAS. The influence of sample andbackground electrolyte pH values on the analytes’ separation and recovery wasinvestigated. The separation time and sample zone length were optimized. Thelimit of detection for both analytes was 1 ng/mL. RSD of the experimentswas about 10%.
Natural and synthetic apatites as sorbentsfor Cd2+ and Cr3+ ions from aqueous solutions; 75–90
Merike Peld, Kaia Tõnsuaadu, and Villem Bender
Abstract. The sorption of Cd2+and Cr3+ ions from aqueous solutions was investigated on differentnatural and synthetic apatites. The sorption of Cd2+ depends mainlyon the apatite specific surface area, it increases with an increase inmagnesium and a decrease in carbonate content, reaching 20 and 74 mmol per100 g of natural and synthetic apatite, respectively. The sorption of Cr3+ions reaches 250 mmol/100 g and depends substantially on the apatitemagnesium content, the effect of the specific surface area is less important.The sorption of cadmium proceeds mainly by an ion-exchange mechanism, in thecase of chromium also a dissolution–precipitation mechanism is involved.
