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Separation and online preconcentration by multistep stacking with large‐volume injection of anabolic steroids by capillary electrokinetic chromatography using charged cyclodextrins and UV‐absorption detection
Author(s) -
Urban Pawel L.,
GarcíaRuiz Carmen,
García Ma Ángeles,
Marina Ma. Luisa
Publication year - 2005
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200500113
Subject(s) - chemistry , chromatography , methyltestosterone , stacking , analyte , repeatability , capillary electrophoresis , detection limit , absorption (acoustics) , analytical chemistry (journal) , materials science , organic chemistry , medicine , composite material
The separation of three common anabolic steroids (methyltestosterone, methandrostenolone and testosterone) was performed for the first time by capillary EKC. Different charged CD derivatives and bile salts were tested as dispersed phases in order to achieve the separation. A mixture of 10 mmol/L succinylated‐β‐CD with 1 mmol/L β‐CD in a 50 mmol/L borate buffer (pH 9) enabled the separation of the three anabolic steroids in less than 9 min. Concentration LODs, obtained for these compounds with low absorption of UV light, were ~5×10 –5 mol/L. The use of online reverse migrating sample stacking with large‐volume injection (the effective length of the capillary) enabled to improve the detection sensitivity. Sensitivity enhancement factors (SEFs) ranging from 95 (for testosterone) to 149 (for methyltestosterone) were achieved by single stacking preconcentration. Then, the possibilities of multistep stacking to improve the sensitivity for these analytes were investigated. SEFs obtained by double stacking preconcentration ranged from 138 to 185, enabling concentration LODs of 2.79×10 –7 mol/L (for methyltestosterone), 3.47×10 –7 mol/L (for testosterone) and 3.56×10 –7 mol/L (for methandrostenolone). Although online triple stacking preconcentration was achieved, its repeatability was very poor and SEFs for the studied analytes were not calculated.