Rapid measurement of oestradiol and oestriol by high-performance liquid chromatography after automatic pretreatment

Simultaneous determination of estriol and estriol 3-sulfate in serum by column-switching semi-micro high-performance liquid chromatography with ultraviolet and electrochemical detection

A column-switching HPLC with semi-microcolumn enabled us a direct and simultaneous analysis of estriol (E3) and estriol 3-sulfate (E3 S) in human serum in combination with ultraviolet (for E3 S) and electrochemical (for E3) detectors. The mobile phases (phosphate buffer pH 7.0) contained 5 mM tetra-n-butylammonium ion (TBA) as a counter ion for E3 S. Serum samples were diluted with 200 mM phosphate buffer (pH 7.0) containing 100 mM TBA, then injected to the pre-column. After serum proteins had flowed out from the pre-column, E3 and E3 S were transferred to the enrichment column. Subsequently the analytes were eluted to the analytical column. Detection limits of E3 and E3 S in human serum were 2.5 ng/ml and 295 ng/ml. Serum E3 and E3 S levels (mean +/- SD) of umbilical artery from 18 full-term healthy neonates were 33+/-23 ng/ml and 1.26+/-0.69 microg/ml, respectively.

Estradiol permeation from nonionic surfactant vesicles through human stratum corneum in vitro

The permeation of estradiol from vesicular formulations through human stratum corneum was studied in vitro. The vesicles were composed of nonionic n-alkyl polyoxyethylene ether surfactants (CnEOm). The thermodynamic activity of estradiol present in each formulation was kept constant by saturating all formulations with estradiol. The effects of both the particle size and the composition of the formulation on estradiol permeation across excised human stratum corneum were investigated. Stratum corneum that was pretreated with empty surfactant carriers allowed for significantly higher estradiol fluxes compared with untreated stratum corneum. However, estradiol fluxes obtained in these pretreatment experiments appeared to be significantly lower than those obtained by the direct application of the estradiol-saturated carrier formulation on top of the stratum corneum. Furthermore, in the case of pretreatment of the stratum corneum, an increase in carrier size resulted in a decrease in estradiol flux. For direct application the opposite was found. Two mechanisms are proposed to play an important role in vesicle-skin interactions, i.e., the penetration enhancing effect of surfactant molecules and the effect of the vesicular structures that are most likely caused by adsorption of the vesicles at the stratum corneum-suspension interface.

Liquid chromatographic determination of oestradiol in serum by pre-column derivatization with dansyl chloride or laryl chloride and peroxyoxalate chemiluminescence detection

Column liquid chromatography with chemiluminescence detection is used to determine oestradiol in serum. Oestradiol is labelled by means of a two-phase derivatization procedure with either dansyl chloride or laryl chloride. After derivatization the excess reagent is removed on a short amino-bonded column: the sulphonyl chloride functional group reacts with the amino groups causing removal of the label; the oestradiol derivatives are not retained. Chromatography of oestradiol derivatives is performed with methanol-water mixtures as eluent. Chemical excitation is carried out by adding bis(2-nitrophenyl)oxalate and hydrogen peroxide dissolved in acetonitrile to the column eluate. Linearity is observed (r = 0.9998; n = 7) over at least three decades (10(-6)-10(-9) M) for both dansyl chloride and laryl chloride. A detection limit of 5 x 10(-10) M (50 fmol injected) has been achieved and the dansyl derivatization method has been applied to the determination of oestradiol in spiked serum.

Rapid and sensitive on-line precolumn purification and high-performance liquid chromatographic assay for bile acids in serum

A simple and rapid technique for the simultaneous isolation and analysis of fifteen kinds of bile acid was developed using reversed-phase high-performance liquid chromatography with an automatic dual-precolumn switching system. The serum samples were directly injected onto a first precolumn (hydroxyapatite), which was flushed with 1 mM phosphate buffer. Serum proteins were strongly retained on the hydroxyapatite column, but bile acids were unretained. The bile acids were absorbed on a second precolumn (Serumout-25) and eluted onto the analytical column with solvent B (acetonitrile-methanol-30 mM ammonium acetate, 20:20:60, v/v/v). For the separation of each bile acid, the gradient elution technique was used (solvent A was acetonitrile-methanol-30 mM ammonium acetate, 30:30:40). After separation of the bile acids, NADH was produced by use of immobilized 3 alpha-hydroxysteroid dehydrogenase column and then determined fluorimetrically (gamma em = 460 nm, gamma ex = 350 nm). The recoveries of bile acids in serum generally approached 100%.

Clinical analysis of individual steroids by column liquid chromatography

At present, there are various LC methods available for the determination of estriol, aldosterone, and cortisol in urine, and for cortisol, cortisone, 11-deoxycortisol, corticosterone, 17-hydroxyprogesterone, estriol, vitamin D isomers, and various exogenous glucocorticoids in serum. The LC methods are more specific than the currently available RIAs or homogenous immunoassays. However, whether the data obtained by more specific LC methods are better clinically than the commonly used immunoassays for these steroids must still be proven. In this review, I have critically evaluated various LC methods currently available for the routine determination of clinically important steroids in the clinical laboratories. A complete evaluation and advantages and disadvantages of alternative techniques are beyond the scope of this review. However, the readers are urged to refer to the review articles and chapters listed in the reference section.

Automated direct assay system for the measurement of sex steroid hormones in serum using high-performance liquid chromatography

An automated direct assay system using high-performance liquid chromatography was developed for the simultaneous measurement of estradiol, estrone, progesterone, 17 alpha-hydroxyprogesterone, 20 alpha-hydroxyprogesterone, testosterone and androstenedione in biological fluids. A comparison between the values measured by this method and by radioimmunoassay revealed good correlation for estradiol (r = 0.938, p less than 0.001) and progesterone (r = 0.903, p less than 0.001). Estradiol and estrone could be analysed above the level of 250 pg/ml, and progesterone, 17 alpha-hydroxyprogesterone, 20 alpha-hydroxyprogesterone, testosterone and androstenedione could be analysed above the level of 5.0-7.5 ng/ml. The method was applied to the clinical appraisal of placental function and maturation of ovarian follicles.

High-performance liquid chromatography of steroid hormones

Although a considerable amount of work has been carried out in the last ten years in developing methods for the separation of steroids by HPLC, it is still not widespread for the reasons discussed above. There is however no doubt that further developments in HPLC technology, in increasing sensitivity and/or specificity of detection systems, perhaps with microbore columns, may lead to an increase in the use of this powerful analytical procedure as an additional separation method to improve specificity of assay. Solution of the problem of simple interfacing of HPLC systems with mass spectrometers (discussed in another chapter by Games) should further increase the application of HPLC. HPLC is of particular value in providing a means of separating unstable compounds prior to assay by relatively nonspecific quantitation methods. Most steroids do not fall into this category, but the steroid vitamin D and its metabolites do and HPLC has proved in this area to be invaluable (see chapter by Jones & DeLuca). There are a multiplicity of different HPLC systems for the separation of steroids, varying in column type (and manufacturer), solvent composition and method of elution, temperature of elution, etc., and only a few attempts have been made to rationalise these data. It would therefore seem that a fruitful area of future study would be the investigation of computerised systems for the selection and optimisation of HPLC systems for particular steroid separations.