Determination of corticosterone and 17-hydroxycorticosterone in plasma and urine samples by sweeping techniques using micellar electrokinetic chromatography

The analysis of corticosterone in mouse blood serum (metabolic-stress experiment) and 17-hydroxycorticosterone in human urine (exercise-stress experiment) samples by means of capillary electrophoresis/UV absorbance in conjunction with online sample concentration techniques is described. The use of normal MEKC had an analyte detection limit of 7μg/ml (S/N=3); whereas when online sample concentration methods, including sweeping-micellar electrokinetic chromatography (Sweeping-MEKC) and cation-selective exhaustive injection-sweep-micellar electrokinetic chromatography (CSEI-sweep-MEKC) were used, the detection limits could be improved to 3 and 5ng/ml, respectively. In the analysis of actual samples from animal metabolic-stress experiments (39 mouse), chronically stressed animals showed a higher level (552±152ng/ml) and acute stressed animals showed an intermediate level (375±105ng/ml). In comparison, normal animals show a lower concentration level of corticosterone (153±109ng/ml). In addition, based on a human exercise-stress experiment (seven volunteers), the acute stressed humans (after exercise, 800m of running) show a higher concentration of 17- hydroxycorticosterone (113±55ng/ml for males; 128±25 for females) and the non-stressed humans (before exercise) show a lower concentration (63±37ng/ml for male; 60±20 for female), respectively.