Allopregnanolone in the peripartum: Correlates, concentrations, and challenges - A systematic review

BACKGROUND

Allopregnanolone (ALLO) is a metabolite of progesterone and a neuroactive steroid hormone. As a positive allosteric modulator of gamma-aminobutyric acid (GABA) receptors, ALLO seems to have antidepressant and anxiolytic effects, and was therefore approved as a specific medication for the treatment of postpartum depression in 2019. Despite the growing number of publications investigating ALLO levels, results on the biological and psychological correlates in the peripartum period remain inconsistent, possibly due to methodological challenges regarding measurement. To date, however, there is no systematic review examining the correlates, concentrations, and challenges in measuring ALLO in peripartum women.

METHOD

A systematic literature search of PubMed and PsycINFO was conducted in August 2023. Original research articles that measured ALLO concentrations in peripartum women were included. Reports were excluded if they were not original research, included non-human subjects, did not include peripartum women, did not include ALLO measurement as an outcome, included (pharmacological) interventions, constituted method validations, or used the same cohort as another study.

RESULTS

The literature search yielded 234 articles, and two articles were identified from other sources. After full-text screening, 19 articles (N = 1401) met the inclusion criteria, of which seven focused on biological correlates of ALLO and 12 on mood correlates. Of the latter, six found no association between ALLO and mood, four found a negative association, and two found a positive association. Overall, the results show an increase in ALLO levels during pregnancy and a decrease after birth, with levels then remaining low until six months postpartum. ALLO was most commonly measured in blood plasma and by gas chromatography-mass spectrometry (GC-MS). A significant matrix effect was found for blood serum and a significant method effect for radioimmunoassays (RIAs). A significant effect of time of measurement was found.

CONCLUSION

ALLO measurement shows method and matrix effects. ALLO levels are higher when measured in serum compared to in plasma, and when measured using RIA compared to other methods. Time of measurement, study design, and standardization of measurement also influence the reliability of measurement and the interpretation of results.

Detection of methandienone and its metabolites in equine urine, plasma and hair following a multidose oral administration

Methandienone is an anabolic-androgenic steroid that is prohibited in equine sports due to its potential performance enhancing properties. Metabolism and detection of methandienone in equine urine have been investigated comprehensively in literature; however, there is a limited knowledge about its metabolites in equine plasma and no information about its detection in equine hair. Following a multi-dose oral administration of methandienone to two Thoroughbred horses, 17-epimethandienone, methyltestosterone, two mono-hydroxylated, two di-hydroxylated and three 17α-methylandrostanetriol metabolites were detected in plasma. The majority of these were present as free analytes, whilst the mono-hydroxylated metabolites and one isomer of 17α-methylandrostanetriol were partially conjugated. Estimated peak concentrations of methandienone were 6,000 and 11,100 pg/ml; meanwhile, they were 25.4 and 40.5 pg/ml for methyltestosterone. The most abundant analyte in the post-administration plasma samples of both horses was the mono-hydroxylated metabolite; however, the parent compound provided the longest detection (up to 96 h). Screening analysis of hair enabled the detection of methandienone in mane hair samples only, for up to 3 months. Its mono- and di-hydroxylated metabolites were detected with greater peak responses for up to 6 months post-administration in both mane and tail samples, showing that these metabolites could be better analytical targets for hair analysis when administered orally. A follow-up methodology with an extensive wash procedure confirmed the presence of methandienone and its metabolites in a number of post-administration hair samples. Final wash samples were also analysed to assess the degree of internal incorporation (via bloodstream) against possible external deposition (via sweat/sebum).

Derivatization-Enhanced Analysis of Glucocorticoids for Structural Characterization by Gas Chromatography-Orbitrap High-Resolution Mass Spectrometry

Glucocorticoids are classified in section S9 of the Prohibited List of the World Anti-Doping Agency, due to a potential risk to improving physical performance and causing harm to the health of athletes. Based on the similar physiological actions of glucocorticoids, both differentiating known glucocorticoids and identifying unknown glucocorticoids are important for doping control. Gas chromatography coupled with mass spectrometry plays an important role in structural characterization because of abundant structural diagnostic ions produced by electron ionization. It also provides a chance to study the fragmentation patterns. Thus, an enhanced derivatization procedure was optimized to produce trimethylsilylated glucocorticoids and structural diagnostic ions of nineteen trimethylsilylated glucocorticoids were obtained by gas chromatography-orbitrap high-resolution mass spectrometry. In our study, glucocorticoids were classified as: 3-keto-4-ene, 1,4-diene-3-keto, 3α-hydroxy with saturated A-ring, 21-hydroxy-20-keto and halo substituent glucocorticoids based on their structural difference. Structural diagnostic ions that contributed to structural characterization were specifically presented and the fragment patterns were demonstrated according to the above categories. This study not only gave new insights into the structural characterization of these glucocorticoids but also provided evidence for tracing unknown glucocorticoids or chemically modified molecules.

Development and validation of a deep eutectic solvent-assisted liquid-liquid extraction method for simultaneous quantification of six steroid hormones in serum by liquid chromatography-tandem mass spectrometry

Steroid hormones have been reported to be associated with endocrine system diseases. This paper proposes a novel procedure of deep eutectic solvent (DES)-assisted liquid-liquid extraction (LLE) to extract six steroid hormones (including cortisone, cortisol, androstenedione, testosterone, 17-hydroxyprogesterone, and progesterone) from serum coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of five types of L-proline, choline chloride, and citric acid-based DESs were tailored; the DES from L-proline and ethylene glycol at a molar ratio of 1:4 with 20 % acetonitrile was selected as the best-fit assisted solvent for the six steroid hormones compared with other DESs. The parameters for extraction by selected DES were optimized using Box-Behnken design (BBD), and the optimal extraction conditions are 200 µL of acetonitrile, 100 µL of the sample, and 80 µL of DES. Under optimum conditions, the method has good linear calibration ranges (between 0.07 ng mL-1 and 600 ng mL-1), correlation coefficients of determination (r2>0.99), and low limits of quantification (between 0.02 and 0.60 ng mL-1). The extraction recoveries were in the range of 81.84-114.43 %, and the intra-day and inter-day relative standard deviations (RSDs) were less than 10 %.In general, the DES-LC-MS/MS method is a simple and environmentally-friendly method, which can be complementary to the presently available methods for determining steroid hormones in serum.

Improved analysis of derivatized steroid hormone isomers using ion mobility-mass spectrometry (IM-MS)

Over the last decade, applications of ion mobility-mass spectrometry (IM-MS) have exploded due primarily to the widespread commercialization of robust instrumentation from several vendors. Unfortunately, the modest resolving power of many of these platforms (~40-60) has precluded routine separation of constitutional and stereochemical isomers. While instrumentation advances have pushed resolving power to >150 in some cases, chemical approaches offer an alternative for increasing resolution with existing IM-MS instrumentation. Herein we explore the utility of two reactions, derivatization by Girard's reagents and 1,1-carbonyldiimidazole (CDI), for improving IM separation of steroid hormone isomers. These reactions are fast (≤30 min), simple (requiring only basic lab equipment/expertise), and low-cost. Notably, these reactions are structurally selective in that they target carbonyl and hydroxyl groups, respectively, which are found in all naturally occurring steroids. Many steroid hormone isomers differ only in the number, location, and/or stereochemistry of these functional groups, allowing these reactions to "amplify" subtle structural differences and improve IM resolution. Our results show that resolution was significantly improved amongst CDI-derivatized isomer groups of hydroxyprogesterone (two-peak resolution of Rpp = 1.10 between 21-OHP and 11B-OHP), deoxycortisone (Rpp = 1.47 between 11-DHC and 21-DOC), and desoximetasone (Rpp = 1.98 between desoximetasone and fluocortolone). Moreover, characteristic collision cross section (DTCCSN2) measurements can be used to increase confidence in the identification of these compounds in complex biological mixtures. To demonstrate the feasibility of analyzing the derivatized steroids in complex biological matrixes, the reactions were performed following steroid extraction from urine and yielded similar results. Additionally, we applied a software-based approach (high-resolution demultiplexing) that further improved the resolving power (>150). Overall, our results suggest that targeted derivatization reactions coupled with IM-MS can significantly improve the resolution of challenging isomer groups, allowing for more accurate and efficient analysis of complex mixtures.

The use of liquid chromatography-tandem mass spectrometry in newborn screening for congenital adrenal hyperplasia: improvements and future perspectives

Newborn screening for congenital adrenal hyperplasia using 17-hydroxyprogesterone by immunoassay remains controversial despite screening been available for almost 40 years. Screening is confounded by poor immunoassay specificity, fetal adrenal physiology, stress, and illness which can result in a large number of false positive screening tests. Screening programmes apply higher screening thresholds based on co-variates such as birthweight or gestational age but the false positive rate using immunoassay remains high. Mass spectrometry was first applied to newborn screening for congenital adrenal hyperplasia over 15 years ago. Elevated 17-hydroxprogesterone by immunoassay can be retested with a specific liquid chromatography tandem mass spectrometry assay that may include additional steroid markers. Laboratories register with quality assurance programme providers to ensure accurate steroid measurements. This has led to improvements in screening but there are additional costs and added laboratory workload. The search for novel steroid markers may inform further improvements to screening. Studies have shown that 11-oxygenated androgens are elevated in untreated patients and that the adrenal steroidogenesis backdoor pathway is more active in babies with congenital adrenal hyperplasia. There is continual interest in 21-deoxycortisol, a specific marker of 21-hydroxylase deficiency. The measurement of androgenic steroids and their precursors by liquid chromatography tandem mass spectrometry in bloodspots may inform improvements for screening, diagnosis, and treatment monitoring. In this review, we describe how liquid chromatography tandem mass spectrometry has improved newborn screening for congenital adrenal hyperplasia and explore how future developments may inform further improvements to screening and diagnosis.

Development of Fe3O4/reduced graphene oxide nanocomposite-based dispersive solid-phase extraction for the quantification of five steroid hormones

Aim: An accurate and sensitive analytical method was proposed to detect some steroid hormones in biological samples. Materials & methods: An Fe₃O₄/reduced graphene oxide nanocomposite-based dispersive solid-phase extraction was developed for the effective and simple preconcentration of steroid hormones from human serum samples. Results & conclusion: The nanocomposite was firstly used as adsorbent to simultaneously extract the selected hormones. Limit of detection values for the selected hormones were calculated between 5.5 and 39.2 ng/kg (mass based). An artificial serum sample was used to test the applicability and accuracy of the developed method; percentage recovery results obtained from two different spiked concentrations were found to be in the range of 80.5-99.9%.

The use of gas chromatography - high resolution mass spectrometry for suspect screening and non-targeted analysis of per- and polyfluoroalkyl substances

This study is a workflow development for the analysis, identification, and categorization of per- and polyfluoroalkyl substances (PFAS) using gas chromatography-high resolution mass spectrometry (GC-HRMS) with non-targeted analysis (NTA) and suspect screening techniques. The behavior of various PFAS in a GC-HRMS was studied with regards to retention indices, ionization susceptibility, fragmentation patterns, etc. A custom PFAS database was constructed from 141 diverse PFAS. The database contains mass spectra from electron ionization (EI) mode, as well as MS and MS/MS spectra from positive and negative chemical ionization (PCI and NCI, respectively) modes. Common fragments of PFAS were identified across a diverse set of 141 PFAS analyzed. A workflow for suspect screening of PFAS and partially fluorinated products of incomplete combustion/destruction (PICs/PIDs) was developed which utilized both the custom PFAS database and external databases. PFAS and other fluorinated compounds were identified in both a challenge sample (designed to test the identification workflow) and incineration samples suspected to contain PFAS and fluorinated PICs/PIDs. The challenge sample resulted in a 100% true positive rate (TPR) for PFAS which were present in the custom PFAS database. Several fluorinated species were tentatively identified in the incineration samples using the developed workflow.

Use of Trifluoro-Acetate Derivatives for GC-MS and GC-MS/MS Quantification of Trace Amounts of Stera-3β,5α,6β-Triols (Tracers of Δ5-Sterol Autoxidation) in Environmental Samples

Stera-3β,5α,6β-triols make useful tracers of the autoxidation of Δ⁵-sterols. These compounds are generally analyzed using gas chromatography-mass spectrometry (GC-MS) after silylation. Unfortunately, the 5α hydroxyl groups of these compounds, which are not derivatized by conventional silylation reagents, substantially alter the chromatographic properties of these derivatives, thus ruling out firm quantification of trace amounts. In this work, we developed a derivatization method (trifluoroacetylation) that enables derivatization of the three hydroxyl groups of 3β,5α,6β-steratriols. The derivatives thus formed present several advantages over silyl ethers: (i) better stability, (ii) shorter retention times, (iii) better chromatographic properties and (iv) mass spectra featuring specific ions or transitions that enable very low limits of detection in selected ion monitoring (SIM) and multiple reaction monitoring (MRM) modes. This method, validated with cholesta-3β,5α,6β-triol, was applied to several environmental samples (desert dusts, marine sediments and particulate matter) and was able to quantify trace amounts of 3β,5α,6β-steratriols corresponding to several sterols: not only classical monounsaturated sterols (e.g., cholesterol, campesterol and sitosterol) but also, and for the first time, di-unsaturated sterols (e.g., stigmasterol, dehydrocholesterol and brassicasterol).

Rapid Quantification of Endogenous Steroids in Human Serum Using Leidenfrost Effect-Assisted Thermal Desorption Atmospheric Pressure Photoionization Orbitrap Mass Spectrometry

Unconjugated sex steroids in human serum play a crucial role in physiological and pathological studies and are frequently considered as biomarkers in clinical diagnosis. Because of their low polarity, poor volatility, and low concentration, the rapid and highly sensitive analysis of sex steroids in real serum matrix by ambient mass spectrometry is still challenging. Here, Leidenfrost effect-assisted thermal desorption atmospheric pressure photoionization orbitrap mass spectrometry (LETD-APPI-MS) was developed and applied to quantify free sex steroids in human serum without derivatization and chromatography separation within a few minutes. The concentration of target analyte could be increased by approximately two orders during the LETD process. The limit of quantifications and detections of endogenous sex steroids in human serum were measured at the ppt level. In contrast with commonly used immunoassays in clinical laboratories, LETD-APPI-MS enables the accurate measurements of multiple free sex steroids without the interference of cross-reactions. The endogenous sex steroids of 38 female serums at four physiological stages during pregnancy were rapidly tested by LETD-APPI-MS, whose results were highly consistent with that using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS), indicating LETD-APPI-MS has a strong clinical application potential in steroid analysis.

Monitoring Farmed Fish Welfare by Measurement of Cortisol as a Stress Marker in Fish Feces by Liquid Chromatography Coupled with Tandem Mass Spectrometry

The aquaculture industry has become a sustainable source of food for humans. Remaining challenges include disease issues and ethical concerns for the discomfort and stress of farmed fish. There is a need for reliable biomarkers to monitor welfare in fish, and the stress hormone cortisol has been suggested as a good candidate. This study presents a novel method for measurement of cortisol in fish feces based on enzymatic hydrolysis, liquid−liquid extraction, derivatization, and finally instrumental analysis by liquid chromatography coupled with tandem mass spectrometry. Hydrolysis and extraction conditions were optimized. Cortisol appeared to be mostly conjugated to sulfate and less conjugated to glucuronic acid in the studied samples of feces from farmed Atlantic salmon. The method was suitable for quantification of cortisol after enzymatic deconjugation by either combined glucuronidase and sulfatase activity, or by glucuronidase activity alone. The limit of detection was 0.15 ng/g, the limit of quantification was 0.34 ng/g, and the method was linear (R2 > 0.997) up to 380 ng/g, for measurement of cortisol in wet feces. Method repeatability and intermediate precision were acceptable, both with a coefficient of variation (CV) of 11%. Stress level was high in fish released into seawater, and significantly reduced after eight days.

Mass Spectrometry as a Crucial Analytical Basis for Omics Sciences

This review is devoted to the consideration of mass spectrometric platforms as applied to omics sciences. The most significant attention is paid to omics related to life sciences (genomics, proteomics, meta-bolomics, lipidomics, glycomics, plantomics, etc.). Mass spectrometric approaches to solving the problems of petroleomics, polymeromics, foodomics, humeomics, and exosomics, related to inorganic sciences, are also discussed. The review comparatively presents the advantages of various principles of separation and mass spectral techniques, complementary derivatization, used to obtain large arrays of various structural and quantitative information in the mentioned omics sciences.

Multidimensional Separations of Intact Phase II Steroid Metabolites Utilizing LC-Ion Mobility-HRMS

The detection and unambiguous identification of anabolic-androgenic steroid metabolites are essential in clinical, forensic, and antidoping analyses. Recently, sulfate phase II steroid metabolites have received increased attention in steroid metabolism and drug testing. In large part, this is because phase II steroid metabolites are excreted for an extended time, making them a potential long-term chemical marker of choice for tracking steroid misuse in sports. Comprehensive analytical methods, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), have been used to detect and identify glucuronide and sulfate steroids in human urine with high sensitivity and reliability. However, LC-MS/MS identification strategies can be hindered by the fact that phase II steroid metabolites generate nonselective ion fragments across the different metabolite markers, limiting the confidence in metabolite identifications that rely on exact mass measurement and MS/MS information. Additionally, liquid chromatography-high-resolution mass spectrometry (LC-HRMS) is sometimes insufficient at fully resolving the analyte peaks from the sample matrix (commonly urine) chemical noise, further complicating accurate identification efforts. Therefore, we developed a liquid chromatography-ion mobility-high resolution mass spectrometry (LC-IM-HRMS) method to increase the peak capacity and utilize the IM-derived collision cross section (CCS) values as an additional molecular descriptor for increased selectivity and to improve identifications of intact steroid analyses at low concentrations.

Coupling high-resolution mass spectrometry and chemometrics for the structural characterization of anabolic-androgenic steroids and the early detection of unknown designer structures

Predictive models have been developed for the early identification of novel anabolic androgenic steroids and to obtain information on their molecular structure. To this purpose, gas-chromatographic and mass spectrometric characteristic parameters of 136 anabolic androgenic steroids have been specifically considered. Starting from Principal Component Analysis, different chemometric methods were applied, such as classification and clustering techniques, outlining a spectral and structural characterization for each steroid subclass, and considering the contribution of more than 30 variables. Mass spectrometric data on the TMS-derivatives of the target steroids were obtained by gas chromatography coupled to quadrupole-time of flight mass spectrometry using electron ionization. Steroids included in the training set were grouped in 5 subclasses according to their structural similarity, and the experimental data, processed by the chemometric models, allowed the identification of class-specific common fragments and spectral trends. The results of this study, validated on a test set of 21 steroids, have confirmed that the proposed approach allows tracing novel "designer anabolic steroids", including those previously unknown new structures that may have been designed and illicitly synthesized to be invisible to the current anti-doping tests.

Liquid chromatography-mass spectrometry behavior of Girard's reagent T derivatives of oxosteroid intact phase II metabolites for doping control purposes

Intact phase II steroid metabolites have poor product ion mass spectra under collision-induced dissociation (CID) conditions. Therefore, we present herein the liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/(MS)) behavior of intact phase II metabolites of oxosteroids after derivatization. Based on the fact that Girard's reagent T (GRT), as derivatization reagent, was both convenient and efficient in terms of the enhancement in the ionization efficiency and the production of diagnostic product ions related to the steroid moiety, the latter was preferably selected between methoxamine and hydroxylamine upon the model compounds of androsterone glucuronide and androsterone sulfate. Sixteen different glucuronides and 29 sulfate conjugated metabolites of anabolic androgenic steroids (AASs), available either as pure reference materials or synthesized/extracted from administration studies, were derivatized with GRT, and their product ion spectra are presented. Product ion spectra include in all cases high number of product ions that in some cases are characteristic for certain structures of the steroid backbone. More specifically, preliminary results have shown major differences in fragmentation pattern for 17α/17β-isomers of the sulfate conjugates, but limited differentiation for 17α/17β-isomers of glucuronide conjugates and for 3α/3β- and 5α/5β-stereoisomers of both sulfate and glucuronide conjugates. Further to the suggestion of the current work, application on mesterolone administration studies confirmed-according to the World Anti-Doping Agency (WADA) TD2015IDCR-the presence of seven intact phase II metabolites, one glucuronide and six sulfates with use of LC-ESI-MS/(MS).

Sample Multiplexing: Increased Throughput for Quantification of Total Testosterone in Serum by Liquid Chromatography-Tandem Mass Spectrometry

BACKGROUND

For high-volume assays, optimizing throughput reduces test cost and turn-around time. One approach for liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays is sample multiplexing, wherein the analyte of interest is derivatized in different specimens with reagents of different molecular weight (differential mass tagging). Specimens can then be combined and simultaneously analyzed within a single injection to improve throughput. Here we developed and validated a quantitative, sample-multiplexed LC-MS/MS assay for serum total testosterone (TT) based on this approach.

METHODS

For the sample-multiplexed assay, calibrators, controls, and patient specimens were first extracted separately. After mass tagging with either methoxyamine or hydroxylamine, they were combined and injected into the LC-MS/MS system. To evaluate assay performance, we determined limit of quantification (LOQ), linearity, recovery, and imprecision. A method-comparison study was also performed, comparing the new assay with the standard LC-MS/MS assay in 1574 patient specimens.

RESULTS

The method was linear from 2.5 to 2000 ng/dL, with accuracies from 93% to 104% for both derivatives. An LOQ of 1.0 ng/dL was achieved. Intra-assay and total CVs across 4 quality control concentrations were less than 10%. The assay demonstrated good agreement (Deming regression, 1.03x + 6.07) with the standard LC-MS/MS assay for the patient specimens tested (TT, 3 to 4862 ng/dL).

CONCLUSION

Sample multiplexing by differential mass tagging of TT increases LC-MS/MS throughput 2-fold without compromising analytical accuracy and sensitivity.

Approaches in metabolomics for regulatory toxicology applications

Innovative methodological approaches are needed to conduct human health and environmental risk assessments on a growing number of marketed chemicals. Metabolomics is progressively proving its value as an efficient strategy to perform toxicological evaluations of new and existing substances, and it will likely become a key tool to accelerate chemical risk assessments. However, additional guidance with widely accepted and harmonized procedures is needed before metabolomics can be routinely incorporated in decision-making for regulatory purposes. The aim of this review is to provide an overview of metabolomic strategies that have been successfully employed in toxicity assessment as well as the most promising workflows in a regulatory context. First, we provide a general view of the different steps of regulatory toxicology-oriented metabolomics. Emphasis is put on three key elements: robustness of experimental design, choice of analytical platform, and use of adapted data treatment tools. Then, examples in which metabolomics supported regulatory toxicology outputs in different scenarios are reviewed, including chemical grouping, elucidation of mechanisms of toxicity, and determination of points of departure. The overall intention is to provide insights into why and how to plan and conduct metabolomic studies for regulatory toxicology purposes.

Dried blood spots in doping analysis

A series of dried blood spot (DBS) detection methods for doping agents have been developed in the last two decades. The DBS technique minimizes invasiveness and reduces storage and shipping costs. Recently, the World Anti-Doping Agency announced the use of DBS for the 2022 Beijing Winter Olympic Games and Paralympic Games owing to the advantages of the DBS application in routine doping control. Therefore the further development of detection methods for doping agents in DBS is important and urgent. This review summarizes five aspects of DBS application in doping analysis: sample collection, storage conditions, pretreatment, instrumentation and validation according to the Prohibited List issued by the World Anti-Doping Agency, and proposes some suggestions for future studies of DBS in doping analysis.

Mass Spectrometry-Based Steroid Profiling: Meeting Unmet Clinical Needs

Despite ongoing concerns regarding its clinical application, mass spectrometry (MS)-based steroid assay represents a promising tool in endocrine research. Recent studies indicate that monitoring the blood levels of individual sterols provides improved diagnostic insight into hyperlipidemia compared with immunoassays routinely used in clinical practice. Hypercortisolism and hyperaldosteronism can also be easily evaluated along with successful subtyping of adrenal diseases using MS-based methods, while metabolic signatures of sex steroids provide experimental evidence of abnormal puberty and male infertility. Many MS-based biological and clinical studies are based on liquid chromatography-mass spectrometry (LC-MS) coupled to electrospray ionization and tandem MS scan modes. However, gas chromatography-mass spectrometry (GC-MS) provides better chromatographic separation. Improved chromatographic resolution enables large-scale steroid profiling to allow a bird-eye view and increase the chances of identifying potent biomarkers in endocrine research. In addition to the technical advantages of MS-based assays over immunoassays, minimizing the sample amounts with acceptable analytical sensitivity and standardization of surrogate materials provides cutting-edge tools for precision and personalized medicine.

From a single steroid to the steroidome: Trends and analytical challenges

For several decades now, the analysis of steroids has been a key tool in the diagnosis and monitoring of numerous endocrine pathologies. Thus, the available methods used to analyze steroids in biological samples have dramatically evolved over time following the rapid pace of technology and scientific knowledge. This review aims to synthetize the advances in steroids' analysis, from classical approaches considering only a few steroids or a limited number of steroid ratios, up to the new steroid profiling strategies (steroidomics) monitoring large sets of steroids in biological matrices. In this context, the use of liquid chromatography coupled to mass spectrometry has emerged as the technique of choice for the simultaneous determination of a high number of steroids, including phase II metabolites, due to its sensitivity and robustness. However, the large dynamic range to be covered, the low natural abundance of some key steroids, the selectivity of the analytical methods, the extraction protocols, and the steroid ionization remain some of the current challenges in steroid analysis. This review provides an overview of the different analytical workflows available depending on the number of steroids under study. Special emphasis is given to sample treatment, acquisition strategy, data processing, steroid identification and quantification using LC-MS approaches. This work also outlines how the availability of steroid standards, the need for complementary analytical strategies and the improvement of calibration approaches are crucial for achieving complete steroidome quantification.

Determination of Intraprostatic and Intratesticular Androgens

Androgens represent the main hormones responsible for maintaining hormonal balance and function in the prostate and testis. As they are involved in prostate and testicular carcinogenesis, more detailed information of their active concentration at the site of action is required. Since the introduction of the term intracrinology as the local formation of active steroid hormones from inactive precursors of the adrenal gland, mainly dehydroepiandrosterone (DHEA) and DHEA-S, it is evident that blood circulating levels of sex steroid hormones need not reflect their actual concentrations in the tissue. Here, we review and critically evaluate available methods for the analysis of human intraprostatic and intratesticular steroid concentrations. Since analytical approaches have much in common in both tissues, we discuss them together. Preanalytical steps, including various techniques for separation of the analytes, are compared, followed by the end-point measurement. Advantages and disadvantages of chromatography-mass spectrometry (LC-MS, GC-MS), immunoanalytical methods (IA), and hybrid (LC-IA) are discussed. Finally, the clinical information value of the determined steroid hormones is evaluated concerning differentiating between patients with cancer or benign hyperplasia and between patients with different degrees of infertility. Adrenal-derived 11-oxygenated androgens are mentioned as perspective prognostic markers for these purposes.

Improving the detection of anabolic steroid esters in human serum by LC-MS

The detection of the abuse of pseudo-endogenous steroids in sport is articulated in two different levels: an initial testing procedure, based on the longitudinal evaluation of the urinary androgenic steroid profile by gas-chromatography mass spectrometry (GC-MSⁿ), and a confirmation analysis, based on the differentiation between the endogenous and exogenous origin of the pseudo-endogenous steroids by gas-chromatography coupled to isotopic ratio mass spectrometry (GC/C/IRMS). The abuse of pharmaceutical preparations displaying a carbon isotopic composition values within a range similar to those reported for endogenous urinary steroids makes more difficult the application of GC/C/IRMS technique. To overcome this limitation, the direct detection of an intact synthetic anabolic steroid ester in blood matrices (plasma and/or serum) could supply the unequivocal proof of exogenous administration of pseudo-endogenous steroids. Here we are presenting a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the analysis of 14 testosterone (T) esters and 2 nandrolone (Nand) esters in human serum. Sample pre-treatment consisted of protein precipitation, liquid-liquid extraction and derivatization. The formation of three different derivatives (oxime derivatives, Girard P and Girard T hydrazones) is considered, in order to guarantee an improvement in the detection capability of the assay with respect to underivatized compounds. Once the most suitable derivative was selected, the method was validated, according to the World Anti-Doping Agency (WADA) criteria, in terms of specificity, linearity, limit of detection (LOD), extraction recovery, matrix effect (ion suppression/enhancement), carry over and autosampler stability. The formation of Girard P hydrazones of T and Nand esters provides the best results compared to the underivatized compounds, oxime and Girard T derivatives, respectively. The presented analytical method is specific for all considered compounds and linear in the range of concentrations investigated (0.25-10 ng/mL). The LODs are between 0.03 and 0.30 ng/mL, the extraction recovery higher than 70 % for all esters and no remarkable matrix effect, expressed in terms of ion enhancement and ion suppression, was observed. Finally, the developed and validate method was applied in the analysis of serum samples collected after the administration of a single dose (40 mg, 1 capsule) of testosterone undecanoate (Andriol ®) demonstrating its applicability.

Mass spectral fragmentation analyses of isotopically labelled hydroxy steroids using gas chromatography/electron ionization low-resolution mass spectrometry: A practical approach

RATIONALE

Gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS) is used for routine screening of anabolic steroids in many laboratories after the conversion of polar groups into trimethylsilyl (TMS) derivatives. The aim of this work is to elucidate the origin and formation of common and subclass-specific fragments in the mass spectra of TMS-derivatized steroids. Especially in the context of metabolite identification or analysis of designer drugs, isotopic labelling is helpful to better understand fragment ion generation, identify unknown compounds and update established screening methods.

METHODS

Stable isotope labelling procedures for the introduction of [² H₉ ]-TMS or ¹⁸ O were established to generate perdeuterotrimethylsilylated, mixed deuterated and ¹⁸ O-labelled derivatives for 13 different hydroxy steroids. Fragmentation proposals were substantiated by comparison of the abundances of isotopically labelled and unlabelled fragment ions in unit mass resolution GC/MS. Specific fragmentations were also investigated by high-resolution MS (GC/quadrupole time-of-flight MS, GC/QTOFMS).

RESULTS

Methyl radical cleavage occurs primarily from the TMS groups in saturated androstanes and from the steroid nucleus in the case of enol-TMS of oxo or α,β-unsaturated steroid ketones. Loss of trimethylsilanol (TMSOH) is dependent on steric factors, degree of saturation of the steroid backbone and the availability of a hydrogen atom and TMSO group in the 1,3-diaxial position. For the formation of the [M - 105]⁺ fragment ion, methyl radical cleavage predominates from the angular methyl groups in position C-18 or C-19 and is independent of the site of TMSOH loss. The common [M - 15 - 76]⁺ fragment ion was found in low abundance and identified as [M - CH₃ - (CH₃ )₂ SiH - OH]⁺ . For the different steroid subclasses further diagnostic fragment ions were discussed and structure proposals postulated.

CONCLUSIONS

Stable isotope labelling of oxo groups as well as derivatization with deuterated TMS groups enables the detection of structure-related fragment ion generation in unit mass resolution GC/EI-MS. This may in turn allow us to propose isomeric assignments that are otherwise almost impossible using MS only.

Separation and degradation detection of nanogram-per-litre concentrations of radiolabelled steroid hormones using combined liquid chromatography and flow scintillation analysis

Detection of micropollutants such as steroid hormones occurring in the aquatic environment at concentrations between ng/L and µg/L remains a major challenge, in particular when treatment efficiency is to be evaluated. Steroid hormones are typically analysed using mass-spectrometry methods, requiring pre-concentration and/or derivatisation procedures to achieve required detection limits. Free of sample preparation steps, the use of radiolabelled contaminants with liquid scintillation counting is limited to single-compound systems and require a separation of hormone mixtures before detection. In this work, a method was developed coupling ultra-high-pressure liquid chromatography (UHPLC) with flow scintillation analysis (FSA) for separation and detection of radiolabelled estrone, 17ß-estradiol, testosterone and progesterone. Adjustment of the flow rate of scintillation liquid and UHPLC mobile phase, gradient time, column temperature, and injection volume allowed the separation of steroid hormones and degradation products. The limit-of-detection (LOD = 1.5–2.4 ng/L) and limit-of-quantification (LOQ = 3.4–4.3 ng/L) for steroid hormones were comparable with the current state-of-the-art technique (LC-MS/MS) for non-derivatised compounds. Although the method cannot be applied to real water samples (unless spiked with radiotracers), it serves as a useful tool for the development of water treatment technologies at laboratory scale as demonstrated via: i) adsorption on polymer-based spherical activated carbon, ii) retention in nanofiltration, iii) photodegradation using a photocatalytic membrane.

Determination of the steroid profile in alternative matrices by liquid chromatography tandem mass spectrometry

The simultaneous determination of a broad panel of steroids provides more accurate information about the hormonal status than the detection of a single hormone. For that reason, the determination of the steroid profile, i.e. the endogenous steroid hormones and their main metabolites, has become the most powerful tool for the study of hormonal imbalances. The usefulness of the evaluation of the steroid profile in urine and plasma is widely accepted. However, despite its broad potential applicability, the evaluation of the whole steroid profile in alternative matrices such as amniotic fluid, saliva and breast milk remains almost unexplored. In this research we developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of several steroids and their metabolites in amniotic fluid (28 analytes), saliva (15) and breast milk (12). Sample preparation, chromatographic conditions and mass spectrometric conditions (e.g. ionization species or ion source parameters) were optimized. The method was shown to be linear in the range of endogenous concentrations for all studied metabolites. Intra- and inter-assay accuracies were between 80% and 120% while intra- and inter-precisions were below 20% for all analytes in all matrices. The applicability of the method was evaluated by the comparison between the concentration ranges obtained in healthy volunteers (n = 30 per matrix) and the scarce data previously reported in literature. The concentration ranges for several analytes are reported for the first time. The present methodology represents a useful tool for the comprehensive evaluation of the steroid profile in alternative matrices and can be applicable for different clinical purposes.

MASS SPECTROMETRIC FRAGMENTATION OF TRIMETHYLSILYL AND RELATED ALKYLSILYL DERIVATIVES

This review describes the mass spectral fragmentation of trimethylsilyl (TMS) and related alkylsilyl derivatives used for preparing samples for analysis, mainly by combined gas chromatography and mass spectrometry (GC/MS). The review is divided into three sections. The first section is concerned with the TMS derivatives themselves and describes fragmentation of derivatized alcohols, thiols, amines, ketones, carboxylic acids and bifunctional compounds such as hydroxy- and amino-acids, halo acids and hydroxy ethers. More complex compounds such as glycerides, sphingolipids, carbohydrates, organic phosphates, phosphonates, steroids, vitamin D, cannabinoids, and prostaglandins are discussed next. The second section describes intermolecular reactions of siliconium ions such as the TMS cation and the third section discusses other alkylsilyl derivatives. Among these latter compounds are di- and trialkyl-silyl derivatives, various substituted-alkyldimethylsilyl derivatives such as the tert-butyldimethylsilyl ethers, cyclic silyl derivatives, alkoxysilyl derivatives, and 3-pyridylmethyldimethylsilyl esters used for double bond location in fatty acid spectra. © 2019 Wiley Periodicals, Inc. Mass Spec Rev 0000:1-107, 2019.

Technologies to improve the sensitivity of existing chromatographic methods used for bioanalytical studies

Chromatographic method has long been recognized as the most widely used separation method in bioanalytical research. However, the relatively low sensitivity of existing chromatographic methods remains a significant challenge, as the requirements for experimental procedures become more demanding. This review discusses the main causes for the low sensitivity of chromatographic methods and aims to introduce different technologies for enhancing their sensitivity in the following aspects: (i) different pretreatment methods for improving clean-up efficiency and recovery; (ii) derivatization step for altering the chromatographic behavior of analytes and enhancing MS ionization efficiency; (iii) optimal LC-MS conditions and appropriate separation mechanism; and (iv) applications of other chromatographic methods, including miniaturized LC, 2D-LC, 2D-GC, and supercritical fluid chromatography. Altogether, this review is devoted to summarizing the recent technologies reported in the literature and providing new strategies for the detection of bioanalytes.

Comparison of Strategies for the Determination of Sterol Sulfates via GC-MS Leading to a Novel Deconjugation-Derivatization Protocol

Sulfoconjugates of sterols play important roles as neurosteroids, neurotransmitters, and ion channel ligands in health and disease. In most cases, sterol conjugate analysis is performed with liquid chromatography-mass spectrometry. This is a valuable tool for routine analytics with the advantage of direct sterol sulfates analysis without previous cleavage and/or derivatization. The complementary technique gas chromatography-mass spectrometry (GC-MS) is a preeminent discovery tool in the field of sterolomics, but the analysis of sterol sulfates is hampered by mandatory deconjugation and derivatization. Despite the difficulties in sample workup, GC-MS is an indispensable tool for untargeted analysis and steroid profiling. There are no general sample preparation protocols for sterol sulfate analysis using GC-MS. In this study we present a reinvestigation and evaluation of different deconjugation and derivatization procedures with a set of representative sterol sulfates. The advantages and disadvantages of trimethylsilyl (TMS), methyloxime-trimethylsilyl (MO-TMS), and trifluoroacetyl (TFA) derivatives were examined. Different published procedures of sterol sulfate deconjugation, including enzymatic and chemical cleavage, were reinvestigated and examined for diverse sterol sulfates. Finally, we present a new protocol for the chemical cleavage of sterol sulfates, allowing for simultaneous deconjugation and derivatization, simplifying GC-MS based sterol sulfate analysis.

Measurement of serum steroid profiles by HPLC-tandem mass spectrometry

Accurate investigations of adrenal hormone levels play a vital role in pediatric endocrinology for the detection of steroid-related disorders. In this study, we developed and validated a simultaneous assay for eight serum steroids, i.e., DHEA, androstenedione, testosterone, progesterone, 17‑hydroxyprogesterone, DHEA‑sulfate, pregnenolone‑sulfate and cholesterol-sulfate, using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Serum samples were prepared by liquid-liquid extraction with methyl t‑butyl ether. Quantitation by LC-MS/MS was performed in multiple reaction monitoring mode with an electrospray ionization source. The run time was 10 min. Analytical performance was evaluated, including imprecision, linearity, ion suppression, carry over and detection capabilities. Serum specimens from 59 children and 120 adults were analyzed to compare the distribution of steroid levels between the groups. All hormones were effectively extracted and separated using our method. The method was essentially free from potential interference and ion suppression. Within-run and between-run imprecision values were <20%. The lower limits of quantification varied from 0.025 to 10 ng/mL. The results were generally good and correlated with those obtained using immunoassay techniques. We developed the HPLC-MS/MS method for the simultaneous measurement of free and sulfated steroid hormones. The performance of the developed method was generally acceptable. Thus, this method may provide a novel approach to steroid profiling in children of age before adrenarche.

A Novel Targeted Analysis of Peripheral Steroids by Ultra-Performance Supercritical Fluid Chromatography Hyphenated to Tandem Mass Spectrometry

Ultra-performance supercritical fluid chromatography–tandem mass spectrometry (UPSFC–MS/MS) is an alternative method for steroid analysis. Continuous development of analytical methodologies for steroid profiling is of major importance in the clinical environment to provide useful and more comprehensive data. The aim of this study was to identify and quantify a large number of endogenous steroids from the four major classes (estrogens, androgens, progestogens and corticosteroids) simultaneously within a short analytical time. This novel UPSFC–MS/MS method with electrospray in positive ionisation (ESI+) mode is robust, selective and present sufficiently high sensitivity to profile nineteen steroids in 50 µL human plasma. Under optimised conditions, nineteen different steroids were separated with high efficiency in the multiple reaction monitoring (MRM) mode. The linearity of the method was good with correlation coefficients (R²) in the range of 0.9983–0.9999 and with calibration range from 0.05–500 ng/mL in human plasma. The intraday and interday precision of the method, as RSD, was less than 15%. The accuracy of the nineteen analytes varied between 80 to 116%. Finally, the novel method was successfully applied for the determination of nineteen steroids within 5 minutes providing the possibility to use it for research as well as routine healthcare practice.

GC/MS in Recent Years Has Defined the Normal and Clinically Disordered Steroidome: Will It Soon Be Surpassed by LC/Tandem MS in This Role?

Gas chromatography/mass spectrometry (GC/MS) has been used for steroid analysis since the 1960s. The advent of protective derivatization, capillary columns, and inexpensive electron ionization bench-top single quadrupole soon made it the method of choice for studying disorders of steroid synthesis and metabolism. However, the lengthy sample workup prevented GC/MS from becoming routine for steroid hormone measurement, which was dominated by radioimmunoassay. It was the emergence of liquid chromatography/tandem MS (LC/MS/MS) that sparked a renewed interest in GC/MS for the multicomponent analysis of steroids. GC/MS is excellent at providing an integrated picture of a person's steroid metabolome, or steroidome, as we term it. We review the recent work on newly described disorders and discuss the technical advances such as GC coupling to triple quadrupole and ion trap analyzers, two-dimensional GC/MS, and alternative ionization and detection systems such as atmospheric pressure chemical ionization (APCI) and time of flight. We believe that no novel GC/MS-based technique has the power of GC(electron ionization)/MS/MS as a "discovery tool," although APCI might provide ultimate sensitivity, which might be required in tissue steroidomics. Finally, we discuss the role of LC/MS/MS in steroidomics. This remains a challenge but offers shorter analysis times and advantages in the detection and discovery of steroids with a known structure. We describe recent advances in LC/MS steroidomics of hydrolyzed and intact steroid conjugates and suggest the technique is catching up with GC/MS in this area. However, in the end, both techniques will likely remain complementary and both should be available in advanced analytical laboratories.

GC/MS in Recent Years Has Defined the Normal and Clinically Disordered Steroidome: Will It Soon Be Surpassed by LC/Tandem MS in This Role?

Gas chromatography/mass spectrometry (GC/MS) has been used for steroid analysis since the 1960s. The advent of protective derivatization, capillary columns, and inexpensive electron ionization bench-top single quadrupole soon made it the method of choice for studying disorders of steroid synthesis and metabolism. However, the lengthy sample workup prevented GC/MS from becoming routine for steroid hormone measurement, which was dominated by radioimmunoassay. It was the emergence of liquid chromatography/tandem MS (LC/MS/MS) that sparked a renewed interest in GC/MS for the multicomponent analysis of steroids. GC/MS is excellent at providing an integrated picture of a person's steroid metabolome, or steroidome, as we term it. We review the recent work on newly described disorders and discuss the technical advances such as GC coupling to triple quadrupole and ion trap analyzers, two-dimensional GC/MS, and alternative ionization and detection systems such as atmospheric pressure chemical ionization (APCI) and time of flight. We believe that no novel GC/MS-based technique has the power of GC(electron ionization)/MS/MS as a “discovery tool,” although APCI might provide ultimate sensitivity, which might be required in tissue steroidomics. Finally, we discuss the role of LC/MS/MS in steroidomics. This remains a challenge but offers shorter analysis times and advantages in the detection and discovery of steroids with a known structure. We describe recent advances in LC/MS steroidomics of hydrolyzed and intact steroid conjugates and suggest the technique is catching up with GC/MS in this area. However, in the end, both techniques will likely remain complementary and both should be available in advanced analytical laboratories.

Targeting human urinary metabolome by LC-MS/MS: a review

Urine is a biological matrix that contains hundreds of metabolic end products which constitute the urinary metabolome. The development and advances on LC-MS/MS have revolutionized the analytical study of biomolecules by enabling their accurate identification and quantification in an unprecedented manner. Nowadays, LC-MS/MS is helping to unveil the complexity of urine metabolome, and the results obtained have multiple biomedical applications. This review focuses on the targeted LC-MS/MS analysis of the urine metabolome. In the first part, we describe general considerations (from sample collection to quantitation) required for a proper targeted metabolic analysis. In the second part, we address the urinary analysis and recent applications of four relevant families: amino acids, catecholamines, lipids and steroids.

The utility of ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS) for clinically relevant steroid analysis

Liquid chromatography tandem mass spectrometry (LC-MS/MS) assays are considered the reference standard for serum steroid hormone analyses, while full urinary steroid profiles are only achievable by gas chromatography (GC-MS). Both LC-MS/MS and GC-MS have well documented strengths and limitations. Recently, commercial ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS) systems have been developed. These systems combine the resolution of GC with the high-throughput capabilities of UHPLC. Uptake of this new technology into research and clinical labs has been slow, possibly due to the perceived increase in complexity. Here we therefore present fundamental principles of UHPSFC-MS/MS and the likely applications for this technology in the clinical research setting, while commenting on potential hurdles based on our experience to date.

Current state of bioanalytical chromatography in clinical analysis

Chromatographic methods have become popular in clinical analysis in both routine and research laboratories.

Steroid hormone profiling in human breast adipose tissue using semi-automated purification and highly sensitive determination of estrogens by GC-APCI-MS/MS

Body mass index is a known breast cancer risk factor due to, among other mechanisms, adipose-derived hormones. We developed a method for steroid hormone profiling in adipose tissue to evaluate healthy tissue around the tumor and define new biomarkers for cancer development. A semi-automated sample preparation method based on gel permeation chromatography and subsequent derivatization with trimethylsilyl (TMS) is presented. Progestagens and androgens were determined by GC-EI-MS/MS (LOQ 0.5 to 10 ng/g lipids). For estrogen measurement, a highly sensitive GC-APCI-MS/MS method was developed to reach the required lower limits of detection (0.05 to 0.1 ng/g lipids in matrix, 100-200 fg on column for pure standards). The combination of the two methods allows the screening of 27 androgens and progestagens and 4 estrogens from a single sample. Good accuracies and repeatabilities were achieved for each compound class at their respective limit of detection. The method was applied to determine steroid hormone profiles in adipose tissue of 51 patients, collected both at proximity and distant to the tumor. Out of the 31 tested steroid hormones, 14 compounds were detected in human samples. Pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone (DHEA), and androstendione accounted together for 80% of the observed steroid hormone profiles, whereas the estrogens accounted for only 1%. These profiles did not differ based on sampling location, except for ß-estradiol; steroid hormone conversions from androgens to estrogens that potentially take place in adipose or tumoral tissue might not be detectable due a factor 100 difference in concentration of for example DHEA and ß-estradiol. Graphical Abstract Schematic overview of the determination of steroid hormones and metabolites in adipose tissue in proximity and distal to the tumor.

Human and livestock waste as a reduced carbon source contributing to the release of arsenic to shallow Bangladesh groundwater

Recent studies have demonstrated that the supply of relatively young organic carbon stimulates the release of arsenic to groundwater in Bangladesh. This study explores the potential role of human and livestock waste as a significant source of this carbon in a densely populated rural area with limited sanitation. Profiles of aquifer sediment samples were analyzed for phytosterols and coprostanol to assess the relative contributions of plant-derived and human/livestock waste-derived organic carbon at two well-characterized sites in Araihazar. Coprostanol concentrations increased with depth from non-detection (<10m at Site B and <23m at Site F) to maxima of 1.3 and 0.5ng/g in aquifer sands recovered from 17m (Site B) and 26m (Site F), respectively. The commonly used sewage contamination index ([5β-coprostanol]/([5α-cholestanol]+[5β-coprostanol])) exceeds 0.7 between 12 and 19m at Site B and between 24 and 26m at Site F, indicating input of human/livestock waste to these depths. Urine/fecal input within the same depth range is supported by groundwater Cl/Br mass ratios >1000 compared to Cl/Br <500 at depths >50m. Installed tube wells in the area's study sites may act as a conduit for DOC and specifically human/livestock waste into the aquifer during flood events. The depth range of maximum input of human/livestock waste indicated by these independent markers coincides with the highest dissolved Fe (10-20mg/L) and As (200-400μg/L) concentrations in groundwater at both sites. The new findings suggest that the oxidation of human/livestock waste coupled to the reductive dissolution of iron-(oxy)-hydroxides and/or arsenate may enhance groundwater contamination with As.