Biomedical subjects

Urtzi Akesolo

Publications and source records attributed to Urtzi Akesolo.

3 recordsLinked to original sources

PubMed2003

Multivariate optimisation of a cyclodextrin-assisted-capillary zone electrophoretic method for the separation of torasemide and its metabolites.

In this work, a rapid cyclodextrin-assisted capillary electrophoretic method is developed for the separation of the diuretic torasemide and three of its metabolites. Both fractional factorial and central composite designs were employed to optimise the separation method. The factors studied were pH, concentration of methyl-beta-cyclodextrin, concentration of the background electrolyte and percentage of acetonitrile as organic modifier. Monitored response was a composite quality response (Q*) which balanced conflicting normalized responses, such as resolution and migration time. Optimal separation of the four studied compounds was achieved in less than 6.5 min, using an electrolyte of 60 mM borate buffer with no organic modifier and 25 mM methyl-beta-cyclodextrin concentration adjusted to pH 8.0 at a potential of 30 kV. Detection wavelength and temperature were 197 nm and 20 degrees C respectively. This work means a significant improvement with regard to a previous separation method for these compounds developed in our laboratory.

Cyclodextrins↗

PubMed2002

Application of capillary zone electrophoresis to the screening of some angiotensin II receptor antagonists.

A capillary zone electrophoretic (CZE) method was optimized for the separation of five angiotensin II receptor antagonists (Losartan, Irbesartan, Valsartan, Telmisartan and Eprosartan) and two of their metabolites (EXP 3174 and Candesartan M1) by means of experimental design methodologies. The aim of this study was to define rapidly experimental conditions under which the analytes can be resolved for quantitation. The effects of the buffer (pH, concentration and composition), the organic modifier and voltage were studied. Critical factors were identified in a screening design (fractional factorial design) and sequentially an optimization design (central composite design) was used to choose optimal conditions for separation. The most favorable electrophoretic conditions were found by setting the resolution at a threshold value (Rs < or = 1.5) and minimizing, if possible, analysis time. Successful results were obtained with a 50 mM potassium dihydrogen phosphate:boric acid (25:75 v/v) buffer at pH 5.5 in the presence of 5% methanol and application of a 25 kV voltage. Analysis time was 8 min in a conventional fused-silica capillary (50 cm effective length) in a normal cationic mode (anode at the inlet and cathode at the outlet) after hydrostatical sample injection for 30 s.

Acrylates↗

PubMed2002

Separation of the high-ceiling diuretic Torasemide and its metabolites by capillary zone electrophoresis with diode-array detection.

A capillary zone electrophoretic method was developed for the separation of the high-ceiling loop diuretic Torasemide and three of its metabolites (M1, M3 and M5) using an experimental design approach. Two different experimental designs were employed to optimize the developed method: (i) a fractional factorial design examining six factors at two levels (2(6-2)) and (ii) a central composite design examining two factors at two levels (2(2)+2x2+p). The factors studied were: pH, buffer concentration, proportion of boric acid in the mixed boric acid:potassium dihydrogen phosphate background electrolyte, temperature, applied voltage and percentage of organic modifier. Resolution between peaks was established as response. Separation of the four studied compounds was achieved in less than 8 min, using an electrolyte of 20 mM boric acid:potassium dihydrogen phosphate (75:25 v/v) with 15% MeOH adjusted to pH 9.7 with KOH, at a potential of 28 kV. Detection wavelength and temperature were 206 nm and 35 degrees C, respectively.

Diuretics↗