Simultaneous determination of nine endogenous steroids in human urine by polymeric‐mixed micelle capillary electrophoresis

Abstract

A new CE system based on the use of polymeric-mixed micelles (cholic acid, SDS and the poloxamine Tetronic(®) 1107) was developed for the simultaneous determination of nine steroids in human urine. This method allows the baseline separation and quantitation of cortisol, androstenedione, estriol, dehydroepiandrosterone sulfate, testosterone, dehydroepiandrosterone, estrone, progesterone and estradiol in less than 25 min showing to be sensitive enough to detect low concentrations of these steroids in urine samples (5-45 ng/mL). The optimized electrophoretic conditions were performed using a 50 cm × 75 μm capillary, 18 kV, 25°C, with 44 mM cholic acid, 10 mM SDS, 0.05% w/v tetronic(®) 1107, 2.5% v/v methanol, 2.5% v/v tetrahydrofuran in 5 mM borate - 5 mM phosphate buffer (pH=8.0) as a background electrolyte and a dual 210/254 UV-detection. The method can simultaneously determine 0.1-120 μg/mL, which corresponds to 5-6000 ng/mL of steroids in 2 mL urine. The recoveries ranged between 82.4 and 101.5%. Due to its simplicity, speed, accuracy and reliability, the proposed method could be a potential alternative to the traditional methodologies used with clinical purposes.

Development of a novel dual CD‐MEKC system for the systematic flavonoid fingerprinting of Ligaria cuneifolia (R. et P.) Tiegh.—Loranthaceae—extracts

“…Several variables were considered for optimization: sodium tetraborate concentration and pH as well as additives. The inclusion of S‐β‐CD in the sample matrix was also evaluated as it was a good component for providing a pronounced stacking effect and subsequent enhancement in sensitivity for detecting hydrophobic compound as well as being an excellent solubilizing agent . When the sample was prepared in a low conductivity diluent, a stacking mechanism took place, explained on the basis of field amplification .…”

Evaluation of various approaches to the isolation of steroid hormones from urine samples prior to FASS‐MEKC analysis

“…It is worth noting that the SPE technique allows the isolation and concentration of a wide spectrum of analytes differing in volatility and hydrophobicity. However, the most important advantage of SPE is the ability to store the adsorbing analyte for a long time with no formation of an emulsion (which sometimes occurs in the case of LLE and dispersive liquid–liquid microextraction (DLLME) techniques . Moreover, compared to LLE, the SPE technique involves a low cost of the proceedings and reduces the problem of toxic waste.…”

“…Thus, the main aim of the present study was to develop a method for the separation and quantification of selected steroid hormones that could be used in clinical and/or doping control studies taking into account physiological levels of steroid hormones in the human body. For example, the physiological urinary cortisol level is between 50 and 200 ng/mL, whereas the progesterone level in the follicular phase is between 0.8 and 3.0 ng/mL, after ovulation (1.7–27 ng/mL), during pregnancy (9–200 ng/mL), and in man 0.2–1.38 ng/mL . The normal levels of testosterone and epitestosterone in healthy male urine are both in the range of 30–60 ng/mL .…”

Simultaneous separation and determination of praeruptorin A, B and C by micellar electrokinetic chromatography using sodium dodecyl sulphate and sodium cholate as mixed micelles

“…At the same time, with surfactants added in the electrolyte, the solubility of hydrophobic compounds can be improved significantly. Effective separation could be achieved on the basis of varying partition coefficients of analytes between the aqueous and micelles phases . In MEKC, mixed micelles consisting of two or more different surfactants were used to improve selectivity .…”