Biomedical subjects

M Kaljurand

Publications and source records attributed to M Kaljurand.

4 recordsLinked to original sources

PubMed2002

Application of 1-alkyl-3-methylimidazolium-based ionic liquids in non-aqueous capillary electrophoresis.

In many cases salts, which are liquid at room temperature show a better solubility in organic solvents, and can be used in nonaqueous capillary zone electrophoresis as ionic additives. In this study 1-alkyl-3-methylimidasolium-based ionic liquids were used as additives in separation media to assess the interactions between the analytes and the ionic additive present and to find an influence of the type and concentration of the ionic additive, also the nature of the nonaqueous medium employed. Different organic solvents (acetonitrile and methanol) contribute differently to the conversion of analytes into a charged form. Complexes with either an anionic or a cationic part of the ionic liquid additive were formed. This was the case for electrophoresis separation of Brønsted acids and polyphenolic compounds.

Electrophoresis, Capillary↗

PubMed2001

On-line coupling of a miniaturized bioreactor with capillary electrophoresis, via a membrane interface, for monitoring the production of organic acids by microorganisms.

Capillary electrophoresis (CE) can be a valuable tool for on-line monitoring of bioprocesses. Production of organic acids by phosphorus-solubilizing bacteria and fermentation of UHT milk were monitored and controlled by use of a membrane-interfaced dialysis device and a home-made microsampler for a capillary electrophoresis unit. Use of this specially designed sampling device enabled rapid consecutive injections without interruption of the high voltage. No additional sample preparation was required. The time resolution of monitoring in this particular work was approximately 2 h, but could be reduced to 2 min. Analytes were detected at low microg mL(-1) levels with a reproducibility of approximately 10%. To demonstrate the potential of CE in processes of biotechnological interest, results from monitoring phosphate solubilization by bacteria were submitted to qualitative and quantitative analysis. Fermentation experiments on UHT milk showed that monitoring of the processes by CE can provide good resolution of complex mixtures, although for more specific, detailed characterization the identification of individual substances is needed.

Acetic Acid↗

PubMed2000

Head column field-amplified stacking from the flow: stabilization of the sample plug position by using backpressure.

Head column-field amplified sample stacking (HC-FASS) is one of the most powerful concentration techniques in capillary electrophoresis. In the present work we demonstrate that a laboratory-designed pneumatic sampler not only enables us to easily perform HC-FASS from stagnant sample solutions but also permits us to carry out HC-FASS from sample stream, which creates an opportunity to lower the detection limit of analytes further. The influence of stacking time in case of the flowing sample on peak efficiencies and resolution is discussed. It is demonstrated that the sample plug length can be kept constant by monitoring the current in the capillary, which controls a feedback system based on backpressure at the capillary outlet.

Electrophoresis, Capillary↗

PubMed1996

Feedback shift register sequences versus uniformly distributed random sequences for correlation chromatography.

Two alternative input sequences are commonly employed in correlation chromatography (CC). They are sequences derived according to the algorithm of the feedback shift register (i.e., pseudo random binary sequences (PRBS)) and sequences derived by using the uniform random binary sequences (URBS). These two sequences are compared. By applying the "cleaning" data processing technique to the correlograms that result from these sequences, we show that when the PRBS is used the S/N of the correlogram is much higher than the one resulting from using URBS.

Algorithms↗