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The simultaneous determination of a large number of steroids (a.k.a. steroid profile) is a powerful tool that provides useful information about the status of steroid hormones. Steroid profile evaluated in matrices such as urine, saliva and plasma provide one-off moment information about the hormonal status and is highly affected by different factors such as circadian rhythm or apprehension to needles. In contrast, the determination of the steroid profile in hair would provide information about the chronic status of the steroid hormones. The objective of the current research was to develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology for the determination of 11 steroids in hair, including 6 hormones and 5 metabolites. We have optimized different parts of the analytical procedure such as (i) hair shredding, (ii) hair amount, (iii) extraction from hair, (iv) extraction time, (v) required extractions and (vi) analytes preconcentration. MS parameters such as the inclusion of ESI- transitions were also evaluated. The optimization of these parameters was found to be critical to achieve the required sensitivity for the determination of steroids in hair. The method was validated with appropriate linearity in the endogenous range, intra- and inter-assay accuracies and matrix effect between 80% and 120% and intra- and inter-assay precisions below 20% for all analytes. Most of the analytes showed to be stable up to 10 months at room temperature. The suitability of the method was evaluated by obtaining the endogenous concentration range of steroids in 30 healthy volunteers. Results agreed with the scarce data previously reported for some steroids. For others, endogenous concentration ranges in hair were reported for the first time. Additionally, the method was used to compare intraindividual levels of steroids in beard and hair. Results revealed that with the exception of testosterone, beard is a suitable alternative to the hair determination of the steroid profile. In summary, the present strategy to evaluate the steroid profile in hair may be a useful tool with a high potential for a wide range of clinical purposes., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Quantitative determination of endogenous compounds in biological samples has still been challenged by the absence of authentic blank matrix. Alternative strategy of surrogate matrix for preparing reference samples are prevalent due to its low cost and high availability. However, the evaluation system of surrogate matrix is not perfect. Herein, a novel multifunctional isotopic standards based steroidomics strategy was developed. Isotope-labeled standards were used not only as internal standards but also for the evaluation the feasibility of surrogate matrix, which improved the accuracy of assessment and could provide a new prospect for the quantitative analysis of endogenous compounds. Based on this approach, a detailed optimization from LC separation, MS detection to extraction conditions for global steroids in the steroidogenesis was firstly carried out. Characteristics and regularities of steroids in LC-MS were summarized to make references for further targeted or untargeted steroidomics study. Then eighteen steroids were quantified with high accuracy and high sensitivity in plasma from four types of cancer patients and healthy subjects using 1% BSA in PBS as surrogate matrix. And multi-steroids indexes with the best discriminating ability for lung, colorectal, breast and gastric cancer in different genders were identified successfully with Student's t-test, PLS-DA and logistic regression- ROC curve analysis. Finally, efficient cancer screening workflow was established by integrating the amine submetabolomics and lipidomics data of our previous studies. Taken together, the integrated steroidomics strategy could shed a light on the guidance for further steroidome as well as other endogenous compounds analysis and may provide a powerful tool for cancer diagnosis., Competing Interests: Declaration of Competing Interest The authors declared that they have no conflicts of interest to this work., (Copyright © 2019. Published by Elsevier B.V.)

Steroid hormones are a type of crucial substances that mediate numerous vital physiological functions. The comprehensive detection of steroid hormones can help understand the physiopathologic mechanism of steroid hormone-related diseases. It is very difficult to determine steroid hormones in biological samples due to their low endogenous concentrations and poor ionization efficiency. In this study, an efficient and sensitive approach was developed for profiling steroid hormones by combining liquid-liquid extraction and parallel derivatization with liquid chromatography-tandem mass spectrometry. Methoxyamine and dansyl chloride were used to derivatize steroid hormones containing carbonyl and phenolic hydroxyl groups, respectively. Our established method achieved simultaneous analysis of carbonyl and phenolic hydroxyl-containing steroid hormones and could cover estrogens, androgens, corticoids and progestogens. Twenty-nine steroid hormones were detected at pg/mL levels with the sensitivity enhanced by three orders of magnitude after derivatization. The linearity (with linear range of 2-4 orders of magnitude), precision (less than 15%) and recovery (71.1-128.7%) were satisfactory for quantitative analysis of steroid hormones. Finally, the established method was successfully employed to the determination of steroid hormones in serum samples of healthy males and females as well as ovarian cancer patients. The results showed that this approach was suitable and reliable for routine test of steroid hormones containing carbonyl and phenolic hydroxyl groups., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019. Published by Elsevier B.V.)

A novel poly(4-vinylpyridine) based stationary phase was investigated for its performance under supercritical fluid chromatography (SFC) mode. Due to its unique structure, this stationary phase has high molecular planarity recognition ability for aromatic samples possessing the same number of aromatic rings and π-electrons. Taking advantage of the planarity recognition ability observed, separations of structurally similar polycyclic aromatic hydrocarbons and steroids were achieved. This novel stationary phase afforded good peak symmetry for both acidic and basic active pharmaceutical ingredients even when excluding the use of additives such as acids, bases, and salts. These findings may be attributed to the polymeric pyridyl groups covalently-attached on silica gel, which will effectively shield the undesirable interaction between residual silanol groups on the surface and the analytes. Moreover, the properties of pyridyl group on the selector can be reversibly tuned to cationic pyridinium form by eluting trifluoroacetic acid containing modifier. Column robustness toward cycle durability testing was also confirmed., (Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.)

In recent years, there has been an increasing worldwide interest in the use of alternative sample preparation methods that are proceeded by separation techniques. Fused deposition modeling (FDM) is a 3D printing technique that is based the consecutive layering of softened/melted thermoplastic materials. In this study, a group of natural steroids and sexual hormones - namely, aldosterone, cortisol, β-estradiol, testosterone, dihydrotestosterone, and synthetic methyltestosterone and betamethasone - were separated and determined using an optimized high-performance liquid chromatography coupled to mass spectrometry (LC-MS) method in positive ionization mode. 3D-printed sorbents were selected as the pre-concentration technique because they are generally low cost, fast, and simple to make and automate. Furthermore, the use of 3D-printed sorbents helps to minimize potential errors due to their repeatability and reproducibility, and their ability to eliminate carry over by using one printed sorbent for a single extraction of steroids from biological matrices. The extraction procedure was optimized and the parameters influencing 3D-printed Layfomm 60 ® based sorbent and LC-MS were studied, including the type of extraction solvent used, sorption and desorption times, temperature, and the salting-out effect. To demonstrate this method's applicability for biological sample analysis, the SPME-LC-MS method was validated for its ability to simultaneously quantify endogenous steroids. This evaluation confirmed good linearity and an R 2 that was between 0.9970 and 0.9990. The recovery rates for human plasma samples were 86.34-93.6% for the studied steroids with intra- and inter-day RSDs of 1.44-7.42% and 1.44-9.46%, respectively. To our knowledge, this study is the first time that 3D-printed sorbents have been used to extract trace amounts of endogenous low-molecular-weight compounds, such as steroids, from biological samples, such as plasma., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Sorbents were prepared by cross-linking β-cyclodextrin (β-CD) using two different types of cross-linker units at variable reactant mole ratios. The resulting polymers containing β-CD were evaluated as sorbents in micro-solid phase extraction (μ-SPE) format for the extraction of the endogenous steroids testosterone (T), epitestosterone (E), androsterone (A), etiocholanolone (Etio), 5α-androstane-3α,17β-diol (5αAdiol) and 5β-androstane-3α,17β-diol (5βAdiol). The best sorbent (C1; cyclodextrin polymer) showed superior extraction characteristics compared with commercial sorbents (C18 and Bond Elut Plexa). Parameters influencing the extraction efficiency of the C1 sorbent such as extraction and desorption times, desorption solvent and volume of sample were investigated. The extracts were separated using a Hypersil Gold column (50 × 2.1 mm, 1.9 μm) under gradient elution coupled to a LC-MS/MS. The compounds were successfully separated within 8 min. The method offers good repeatability (RSD < 10%) and linearity (r 2  > 0.995) were within the range of 1-200 ng mL -1 for T and E, 250-4000 ng mL -1 for A and Etio and 25-500 ng mL -1 for 5αAdiol and 5βAdiol, respectively. The method was applied for the determination of steroid profile of urine from volunteers., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A limited specificity is inherent to immunoassays for steroid hormone analysis. To improve selectivity mass spectrometric analysis of steroid hormones by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been introduced in the clinical laboratory over the past years usually with low mass resolution triple-quadrupole instruments or more recently by high resolution mass spectrometry (HR-MS). Here we introduce liquid chromatography-high resolution tandem mass spectrometry (LC-MS/HR-MS) to further increase selectivity of steroid hormone quantification. Application of HR-MS demonstrates an enhanced selectivity compared to low mass resolution. Separation of isobaric interferences reduces background noise and avoids overestimation. Samples were prepared by automated liquid-liquid extraction with MTBE. The LC-MS/HR-MS method using a quadrupole-Orbitrap analyzer includes eight steroid hormones i.e. androstenedione, corticosterone, cortisol, cortisone, 11-deoxycortisol, 17-hydroxyprogesterone, progesterone, and testosterone. It has a run-time of 5.3min and was validated according to the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) guidelines. For most of the analytes coefficient of variation were 10% or lower and LOQs were determined significantly below 1ng/ml. Full product ion spectra including accurate masses substantiate compound identification by matching their masses and ratios with authentic standards. In summary, quantification of steroid hormones by LC-MS/HR-MS is applicable for clinical diagnostics and holds also promise for highly selective quantification of other small molecules., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Steroid analysis is being conquered by liquid chromatography tandem mass spectrometry (LC-MS/MS) benefiting from higher standardization, selectivity and diversity. Regarding high throughput in routine diagnostics rapid chromatography is mandatory. Introducing MS(3) (MS/MS/MS), specificity of mass spectrometric detection can be enhanced without sacrificing analysis time. 100mL of human plasma/serum, saliva, urine and 10-20mg of hair are used for the simultaneous quantification of 17α-hydroxyprogesterone, aldosterone, androstenedione, cortisol, cortisone, dehydroepiandrosterone sulfate (DHEAS), estradiol, progesterone, and testosterone using online solid phase extraction (SPE) LC-MS/MS or LC-MS(3). Steroids can be analyzed in 4min after a single manual dilution and protein precipitation step. In complex sample matrices like hair MS(3) detection was found to be appropriate for quantitation. Lower limits of quantitation ranged from 37pmol/L (estradiol) up to 3.1nmol/L (DHEAS). General accuracy was 89-107% with between-run imprecision ≤10%. Comparison to immunoassays revealed significant differences in quantitation for urinary cortisol (-71% mean), aldosterone (-40% mean) and plasma aldosterone (-45% mean). The comparison of MS(2) and MS(3) quantitation of hair cortisol also revealed significant differences. In general, quantitation via MS(3) was not applicable for a long time. But with the current generation of mass spectrometers quantitation via MS(3) can be superior to MS(2) regarding specificity and accuracy when dealing with matrix issues. However, drawbacks regarding flexibility and precision have to be taken into account. Concludingly, simple protein precipitation combined with rapid online SPE LC-MS/MS/MS allows us to quantify over broad, essential concentration ranges in human serum, saliva, urine and hair., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this study, we describe the synthesis of graphene oxide functionalized with the ionic liquid 1-butyl-3-aminopropyl imidazolium chloride and its use as an adsorbent for the dispersive solid-phase microextraction (micro SPE) of four anabolic steroids and six β-blockers from aqueous samples of environmental importance, prior to their HPLC-diode array detector analysis. As the ionic liquid is covalently attached to graphene oxide sheets, it is made possible for it to participate in the dispersive micro SPE procedure. The limits of detection and limits of quantification of the proposed method were found to be in the range of 7-23ng/L and between 20 and 70ng/L, respectively. The linearity was satisfactory, with the determination coefficients to range from 0.9940 to 0.9998 while the within- and between-day relative standard deviation of the method ranged between 3.1 and 7.6% and from 4.0 to 8.5%, respectively. In order to test the applicability of the proposed method in real-life samples, the effluent from a municipal wastewater treatment plant as well as natural water samples from two rivers and a lake were collected and analyzed. After the analysis of samples, the effluent from municipal wastewater treatment plant was fortified with the analytes, at concentrations equal to 2 and 10 times the LOQs. Recoveries were calculated after subtracting the native (no-spike) concentrations of analytes, when needed. All the recoveries were in the range of 87-98%. A comparison study attests to the superiority of the developed nanomaterial over graphene oxide and graphene for the dispersive micro SPE of steroids and β-blockers., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Clay material plays an important role in the transport and retention of many compounds in the soil, therefore, clay based sorbents are promising alternatives for selective sorption of organic pollutants. In the present work, different chain length ionic liquids (ILs) namely, 1-methyl-3-octyl-imidazolium bromide, 1-methyl-3-undecyl-imidazolium bromide and 1-methyl-3-octadecyl-imidazolium bromide were intercalated in the galleries of montmorillonite (MMT) clay. Then, this novel nanofiller surface was utilized in micro extraction of estrogenic hormones for the first time. A fast procedure where sonication-assisted emulsification microextraction combined with vortex assisted micro-solid phase extraction (μ-SPE) was developed for the LC-MS/MS analysis of estrone (E1), 17β-estradiol (E2), estriol (E3) and ethynylestradiol (EE2). The parameters related to the μ-SPE procedure namely; pH, sorbent amount, extraction solvent type and volume, sonication and vortex time, sample volume and salt effect on the extraction efficiency were screened by applying Plackett-Burmann design. The selected parameters were then optimized by using Box-Behnken design. The method was validated for the determination of estrogenic hormone residues in river water samples. Linear calibration plots were obtained for all hormones whose regression coefficients were larger than 0.98. RSD values were found less than 10% for three levels of concentration. LOD levels were calculated as; 0.012, 0.062, 0.018 and 0.693 ng L(-1) for E1, E2, E3 and EE2, respectively. Recovery values were calculated in the range of 86.9-97.7%. Considering large sample volumes required for attaining low limits of these hormones, present method provides an ease for analyst as 10 mL of the sample is adequate for achieving the same sensitivity., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Ion mobility mass spectrometry performed in a compact traveling wave cell (TWIM-MS) is shown to provide a reliable, fast and repeatable method to separate derivatized steroid isomers. Three steroid isomer pairs were analyzed in their native form and as their p-toluenesulfonyl isocyanate derivatives. The native steroids were separated from each other, but no separation could be attained for the isomers. The derivatized steroid isomers were, however, properly separated by TWIM-MS with peak-to-peak resolutions close to or as high as baseline resolution (Rp-p=0.77-1.08)., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The distribution constants of some analytes, closely connected to the petrochemical industry, between an aqueous phase and a phosphonium ionic liquid phase, were determined by ionic liquid micellar electrokinetic chromatography (MEKC). The phosphonium ionic liquids studied were the water-soluble tributyl(tetradecyl)phosphonium with chloride or acetate as the counter ion. The retention factors were calculated and used for determination of the distribution constants. For calculating the retention factors the electrophoretic mobilities of the ionic liquids were required, thus, we adopted the iterative process, based on a homologous series of alkyl benzoates. Calculation of the distribution constants required information on the phase-ratio of the systems. For this the critical micelle concentrations (CMC) of the ionic liquids were needed. The CMCs were calculated using a method based on PeakMaster simulations, using the electrophoretic mobilities of system peaks. The resulting distribution constants for the neutral analytes between the ionic liquid and the aqueous (buffer) phase were compared with octanol-water partitioning coefficients. The results indicate that there are other factors affecting the distribution of analytes between phases, than just simple hydrophobic interactions., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The use of anabolic substances to promote growth in livestock is prohibited within the European Union as laid down in Directive 96/22/EC. Nowadays, efficient methods such as steroid profiling or isotopic deviation measurements allow to control natural steroid hormones abuse. In both cases, urine is often selected as the most relevant matrix and, due to its relatively high content of potential interferents, its preparation before analysis is considered as a key step. In this context, the use of a selective sorbent such as molecularly imprinted polymer (MIP) was investigated. A MIP was synthesized based on 17β-estradiol, methacrylic acid and acetonitrile as template, monomer and porogen, respectively. Two approaches were then tested for non-conjugated (aglycons and glucuronides deconjugated) steroid purification: (i) molecularly imprinted solid phase extraction (MISPE) and (ii) semi-preparative supercritical fluid chromatography with a commercial MIP as stationary phase (SFC-MIP). Parameters for both approaches were optimized based on the main bovine metabolites of testosterone, estradiol, nandrolone and boldenone. The MISPE protocol developed for screening purposes allowed satisfactory recoveries (upper 65% for the 12 target steroids) with sufficient purification for gas chromatography-mass spectrometry (GC-MS) analysis. For confirmatory purposes, the use of isotopic ratio mass spectrometry (IRMS) requires a higher degree of purity of the target compounds, which can be reached by the SFC-MIP protocol with three steps less compared to the official and current method. Purity, concentration and absence of isotopic fractionation of target steroids extracted from urine of treated cattle (treated with testosterone, estradiol, androstenedione, and boldenone) allowed the measurement of (13)C/(12)C isotopic ratios of corresponding metabolites and endogenous reference compounds (ERC) and proved the relevance of the strategy., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The aim of this study was to develop an analytical method for the analysis of traces of hormonal steroids and veterinary and human drugs in soil. Thus, 31 substances were selected, including 14 veterinary products, 11 hormonal steroids and 6 other well-known human contaminant compounds. The procedure inspired by the quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction method was developed. First the acetonitrile-based extraction was optimized. This step was followed by a solid-phase extraction (SPE) clean-up using both a strong anion-exchange cartridge and a polymeric cartridge. The analysis was then performed using liquid chromatography coupled to a triple quadrupole analyser operated with tandem mass spectrometry. This analytical procedure was validated using the ICH/2005 standard by evaluating the linearity (from 0.01 ng/g to 1000 ng/g--R²>0.99), the intra-day precision (relative standard deviation (RSD)<20%), the inter-day precision (RSD<30%), recoveries (40-110% for most of the compounds) and limits of detection and quantification. This method allowed for the determination of the target analytes in the lower ng/g concentration range. The methodology was then applied to real soil samples collected in several areas of France that received different manure or sludge treatments. Some target compounds were detected at very low level (inferior to the ng/g). Veterinary antibiotics, mainly from the sulfonamide family, were found in soils treated by manure (0.02-0.12 ng/g). On the other hand, pharmaceuticals usually used by humans (carbamazepine, ibuprofen) were detected in soils treated by domestic sludge., (Copyright © 2012 Elsevier B.V. All rights reserved.)

In this paper, a convenient and self-assembled hollow fiber solvent-stir bar microextraction (HF-SSBME) device was developed, which could stir by itself. In the extraction process, the proposed device made the solvent "bar" not floating at the sample solution and exposing to air while organic solvents outside hollow fiber always wrapped with donor phase solvent, which reduced the vaporization of organic solvents. This design could improve the precisions and recoveries of experiments. For evaluating the device, seven anabolic steroids (prasterone, 5α-androstane-3α, 17β-diol, methandriol, 19-norandrostenediol, androstenediol, methyltestosterone and methandienone) were used as model analytes and extraction conditions such as type and volume of organic solvents, agitation speed, extraction time, extraction temperature and salt addition were studied in detail. Under the optimum conditions (15 μL toluene, 40 °C, stirring at 750 rpm for 30 min with 1.5 g sodium chloride addition in 20.0 mL donor phase), the linear ranges of anabolic steroids were 0.25-200 ng mL(-1) with gas chromatography-mass spectrometry. The limits of detection were lower than 0.10 ng mL(-1). The recoveries and precisions in spiked urine and hair samples were between 73.97-93.56% and 2.18-4.47% (n=5). HF-SSBME method combined the intrinsical merits of hollow fiber with the superiority of the proposed self-stirring device which can be developed to two-phase, three-phase and in situ derivatization modes with wide prospect of application. Besides, the pedestal of this proposed device can be converted to fix stir bar in stir bar sorptive extraction (SBSE) method., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A novel polymer-grafted stationary phase of high-performance liquid chromatography (HPLC) was developed, utilizing a temperature-responsive polymer containing an aromatic moiety. Firstly, we synthesized novel functional polymer poly(N-isopropylacrylamide-co-N-acryloyl-3-(2-naphthyl)-L-alanine methyl ester) [poly(NIPAAm-co-Nap)], which has temperature-responsiveness and selective retention of aromatic compounds by an intermolecular π-π interaction. The polymer exhibited a significant reversible phase transition from hydrophilic to hydrophobic in the vicinity of its lower critical solution temperature. Employing the developed polymer-grafted silica column, temperature-responsive chromatography was conducted using water as a sole mobile phase. A comparison with a conventional ODS column or a homogeneous PNIPAAm-grafted silica column showed that the retention of aromatic compounds was dramatically increased on the poly(NIPAAm-co-Nap)-grafted stationary phase. Introducing the naphthyl-alanine derivative caused a significant effect on the retention selectivity for aromatic compounds., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The design of a new interface for comprehensive two-dimensional liquid chromatography (LC x LC) is described. To the conventionally used LC x LC system with the loop-type interface consisting of a two-position/ten-port switching valve equipped with two loops, an extra two-position/ten-port switching valve, a detector, a pump and a second column placed in parallel with the column in the second dimension, are added. The features of the interface are that the separation space in the second dimension is significantly enlarged and that the number of fractions transferred from the first to the second dimension can be increased, reducing the risk to lose resolution of the primary dimension. The potential of the system in NPLC x 2RPLC is illustrated with the analysis of a standard mixture and a lemon oil extract. For the lemon oil analysis, the effective peak capacity was increased from 437 using a conventional interface to 1095 with the new interface. RPLC x 2RPLC in combination with reduced modulation times was applied to the analysis of steroids and to the detection of impurities at the 0.05% relative concentration level in a sulfonamide drug sample.

1,2-Dioleyl-3-trymethylammoniumpropane (DOTAP) lipid vesicles were employed as coating precursors to obtain a semipermanent cationic lipid bilayer in silica capillary. The coating procedure was relatively fast and simple. Reliable results for the separation of four basic proteins (alpha-chymotrypsinogen A, ribonuclease A, cytochrome C, lysozyme) were obtained by using an acetate buffer under acidic conditions. The RSDs of the migration times were not higher than 0.5% run-to-run and about 1% day-to-day (3 days), while the RSDs of the peak areas were within 7% day-to-day (3 days). The day-to-day RSD of the EOF mobility of about 1%, confirmed that the DOTAP coating was stable for the separation of basic proteins, under acidic buffers. In addition to basic proteins the DOTAP coating was found suitable under acidic conditions for the repeatable separation of neutral steroids. The potential of DOTAP as a carrier in background electrolyte solution was studied.

Greater stability of liposome coatings and improved resolution of model steroids in capillary electrochromatography (CEC) were sought by adding small diamines (ethylenediamine, diaminopropane, bis-tris-propane, or N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid, HEPES)) to the liposome solution before coating of fused silica capillaries. The phospholipid coatings consisted of 1 mM of 8:2 mol% phosphatidylcholine (PC)/phosphatidylserine (PS) and 5 mM of modifier in buffer solutions (acetate, phosphate, or Tris) at pH 4.0-7.4. The coating was based on a published procedure, and five steroids were used as neutral model analytes in evaluation of the coating. The results showed that under optimal conditions, the small linear diamines increased the packing density of anionic phospholipids, leading to improved separations. In addition, the choice of buffer for the liposome coating and separation appeared to influence the performance of the coatings. While buffers with amino groups take part in the phospholipid bilayer formation, buffers like phosphate may even have negative effect on coating formation. The factors affecting phospholipid coatings with diamines as modifiers are clarified.

Complementary on-line preconcentration strategies are needed when analyzing different classes of solutes in real samples by capillary electrophoresis (CE) with UV detection. The performance of three different on-line preconcentration (focusing) techniques under alkaline conditions was examined in terms of their selectivity and sensitivity enhancement for a group of steroids, including classes of androgens, corticosteroids and estrogens. Electrokinetic focusing of large sample injection plugs (up to 28% of effective capillary length or 22.1 cm) directly on-capillary can be tuned for specific classes of steroids based on changes in their mobility (velocity) using a multi-section electrolyte system in CE. A dynamic pH junction was applied for the selective resolution and focusing of weakly acidic estrogens using borate, pH 11.0 and pH 8.0 in the background electrolyte and the sample, respectively. Sweeping, using an anionic bile acid surfactant and neutral gamma-cyclodextrin (gamma-CD) under alkaline conditions (pH 8), resulted in focusing and separation of the moderately hydrophobic (non-ionic) classes of steroids, such as androgen and corticosteroids. Optimal focusing and resolution of all test steroids under a single buffer condition was realized by a dynamic pH junction-sweeping format using borate, pH 11.0 and bile acid surfactant with gamma-CD in the BGE, whereas the sample is devoid of surfactant at pH 8.0. The design of selective on-line focusing strategies in CE is highlighted by the analysis of microgram amounts of ethynyl estradiol derived from a female contraceptive pill extract using the dynamic pH junction method, which resulted in over a 100-fold enhancement in concentration sensitivity.

This review is based on a selection of research papers published mainly in the last decade and it describes various analytical aspects of separation and detection of neuroactive steroids in biological matrices.

In this review, we consider the general principles and specific methods for the purification of different classes of phytosteroids which have been isolated from plant sources: brassinosteroids, bufadienolides, cardenolides, cucurbitacins, ecdysteroids, steroidal saponins, steroidal alkaloids, vertebrate-type steroids and withanolides. For each class we give a brief summary of the characteristic structural features, their distribution in the plant world and their biological effects and applications. Most classes are associated with one or a few plant families, e.g., the withanolides with the Solanaceae, but others, e.g., the saponins, are very widespread. Where a compound class has been extensively studied, a large number of analogues are present across a range of species. We discuss the general principles for the isolation of plant steroids. The predominant methods for isolation are solvent extraction/partition followed by column chromatography and thin-layer chromatography/HPLC.

Evaluation of the particle beam glow discharge mass spectrometry (PB-GDMS) system as a detector for liquid chromatography (LC) is described for the analysis of polycyclic aromatic hydrocarbons, steroids, selenoamino acids, and alkyllead compounds. A particle beam interface is used to introduce analyte species from the LC into a glow discharge source for subsequent vaporization and ionization. Mass spectra display classic EI fragmentation patterns for the organic compounds, as well as elemental and molecular information for the organometallic compounds. Chromatographic separations display good temporal correlation between UV and PB-GDMS detection modes. Detection limits for Pb in lead nitrate, triethyllead, and triphenyllead fall in the sub-ppb (ng) range.

In order to gain a commercially acceptable yield compared to the adsorption capacity of the column, a rather large amount of sample is separated with preparative chromatography. During the competitive adsorption of the sample-components, the species adsorbing better can force the rest out of the adsorbent phase. As a consequence, the concentrations of the later components may increase in the fluid phase to a level that those species start to precipitate. A mathematical model which takes the precipitation and dissolution into consideration is presented in this paper. Data calculated by this model are compared to that we obtained by using a previous mathematical model as well as the experimental results gained by a laboratory scale separation of steroid compounds on an organic polymer adsorbent. The equilibrium adsorption-desorption and equilibrium precipitation-dissolution is the first approximation of the complicated process mentioned above. In our next publication we are to extend the model with kinetic terms belonging to adsorption-desorption and precipitation-dissolution process respectively.