An LC/MS/MS method for analyzing the steroid metabolome with high accuracy and from small serum samples.

Analyzing global steroid metabolism in humans can shed light on the etiologies of steroid-related diseases. However, existing methods require large amounts of serum and lack the evaluation of accuracy. Here, we developed an LC/MS/MS method for the simultaneous quantification of 12 steroid hormones: testosterone, pregnenolone, progesterone, androstenedione, corticosterone, 11-deoxycortisol, cortisol, 17-hydroxypregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone, estriol, and estradiol. Steroids and spiked internal standards in 100 µl serum were extracted by protein precipitation and liquid-liquid extraction. The organic phase was dried by evaporation, and isonicotinoyl chloride was added for steroid derivatization, followed by evaporation under nitrogen and redissolution in 50% methanol. Chromatographic separation was performed on a reverse-phase PFP column, and analytes were detected on a triple quadrupole mass spectrometer with ESI. The lower limits of quantification ranged from 0.005 ng/ml for estradiol to 1 ng/ml for cortisol. Apparent recoveries of steroids at high, medium, and low concentrations in quality control samples were between 86.4% and 115.0%. There were limited biases (-10.7% to 10.5%) between the measured values and the authentic values, indicating that the method has excellent reliability. An analysis of the steroid metabolome in pregnant women highlighted the applicability of the method in clinical serum samples. We conclude that the LC/MS/MS method reported here enables steroid metabolome analysis with high accuracy and reduced serum consumption, indicating that it may be a useful tool in both clinical and scientific laboratory research.

LC-MS/MS determination of plasma catecholamines after selective extraction by borated zirconia.

For the first time, boronate affinity chromatography and metal oxide affinity chromatography mechanisms for cis-diol-compounds extraction are simultaneously realized on a single material, termed borated zirconia. This material was prepared by hydrolyzing zirconium butoxide with boric acid under non-aqueous environment. The diameter of formed particles is around 200 nm. By extracting catechol under different pH conditions or with phosphate ion competition, the dual affinity mechanisms of borated zirconia are confirmed. Benefiting from such unique feature, borated zirconia can function well under neutral condition. By using borated zirconia for dispersive solid phase extraction, specific capture of cis-diol-containing catecholamines, including epinephrine (E), norepinephrine (NE) and dopamine (DA), was achieved. A reliable LC-MS/MS method was established and validated for quantification of these target analytes in plasma samples after derivatisation with benzoyl chloride. The linear ranges are 0.010-0.200 ng·mL-1 for E and DA, and 0.050-1.000 ng·mL-1 for NE. The limits of quantification are 0.008, 0.020 and 0.004 ng·mL-1 for E, NE and DA respectively. By analyzing samples from healthy volunteers and schizophrenia patients, the plasma concentrations of E, NE and DA were found to be higher for the latter. Graphical AbstractSchematic representation of boronate combined metal oxide affinity chromatography (BMOAC) extraction of cis-diol catecholamines from human plasma by borated zirconia following with benzoyl chloride derivatization and LC-MS determination.

Steroid profile analysis by liquid chromatography-tandem mass spectrometry in second-trimester pregnant women for trisomy 21 screening.

BACKGROUND: Trisomy 21 is a serious chromosome abnormality. The conventional Down's screening test is the most widely used for trisomy 21 screening. However, this method could lead to a higher false positive rate. Therefore, we aim to analyze steroid profile in second-trimester pregnant women and identify novel serum biomarkers of trisomy 21. METHODS: We employed an LC-MS/MS method to measure the steroid profile. The concentrations and product-to-substrate ratios in 71 second-trimester pregnant women were determined and statistically analyzed to identify novel biomarkers for trisomy 21 screening. RESULTS: We found that there were significant differences in levels of E3, 11-deoxycortisol, and 11-deoxycortisol /17-hydroxyprogesterone between two groups. The OPLS-DA plots revealed obvious separation between two groups. Combining VIP analysis (VIP > 1.0) with volcano plot (P < 0.05 and fold change >1.2 or < 0.83), 11-deoxycortisol was identified as a novel biomarker for trisomy 21. After controlling for confounders, we found 11-deoxycortisol was associated with trisomy 21 (adjusted P = 0.009), and the fully adjusted OR (95 % CI) was 0.098 (0.016-0.593) in highest quartile versus lowest quartile of 11-deoxycortisol (P = 0.011). CONCLUSIONS: Steroid profile analysis for the first time showed that steroid hormones perturbations occurred in pregnant women carrying a fetus affected by trisomy 21 and decreased 11-deoxycortisol levels were associated with trisomy 21.

An LC-MS/MS analysis for seven sex hormones in serum.

BACKGROUND: Comprehensive serum sex hormone profiling is essential for monitoring the occurrence and development of many related diseases. However, the current methods for multi-class sex hormone detection were always lack of Standard Reference Material (SRM) certification and suffered from large sample consumption. For improvement, we developed a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method focused on SRM certification and minimization of serum consumption for simultaneous quantification of seven mainstream serum sex hormones including estrogens (estrone E1, estradiol E2 and estriol E3), androgens (testosterone T, androstenedione AD, dehydroepiandrosterone DHEA) and progestogens (progesterone P). METHODS: To achieve one-batch analysis, a straightforward strategy was designed and carefully optimized. Schematically, serum was firstly spiked with isotope-labeled internal standards. Then, liquid-liquid extraction was performed with methyl tert-butyl ether. After drying under nitrogen, dansyl chloride was introduced for derivatization. Finally, the mixture was submitted to LC-MS/MS for quantification. RESULTS: The limit of quantification was 0.005 ng/mL for E1, E2 and E3, 0.01 ng/mL for T, P and AD, 0.25 ng/mL for DHEA. Inter- and intra-assay CVs were less than 11.8%. The selectivity was proved satisfactory by interference spiking tests. With systematical SRM validation, the mean bias of -5.4 to 4.7% was observed, which indicated excellent method reliability. We found significant positive bias in chemiluminescence immunoassay (CLIA) detection comparing with current method, which promoted us to reconsider our previous results on sex hormone regulation in male patients with coronary atherosclerotic disease. After redetecting the related samples, modified and improved conclusions were proposed. CONCLUSIONS: A LC-MS/MS method for multi-class serum sex hormone profiling was developed with SRM certification and minimized serum consumption. Taking advantages of such reliable method, the previous CLIA-based research findings on sex hormone regulation in male patients with coronary atherosclerosis were modified and improved after redetecting the same sample-pool.

A novel and reliable method for tetrahydrobiopterin quantification: Benzoyl chloride derivatization coupled with liquid chromatography-tandem mass spectrometry analysis.

Tetrahydrobiopterin (BH4) is a crucial cofactor for nitric oxide synthase, acylglycerol mono-oxygenase and aromatic amino acids hydroxylases. Its significant function for redox pathways in vivo attracted much attention for long. However, because of the oxidizable and substoichiometric nature, analysis of BH4 has never been truly achieved with adequate sensitivity and applicability. In the present work, we pioneeringly stabilized BH4 by derivatizing the active secondary amine on five-position with benzoyl chloride (BC). Benefiting from the favorable chemical stability and excellent mass spectrometric sensitivity of the product (BH4-BC), ultra-sensitive and reliable quantification of endogenous BH4 in plasma was achieved using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. In such methodology, BH4-BC-d5 was introduced as stable isotopic internal standard. And the limit of quantification (LOQ) could reach 0.02 ng mL-1. In the end, after investigation of plasma BH4 in healthy volunteers (n = 38), we found that the levels of BH4 were significantly and negatively correlated to age. Comparing with all the other existed strategies, the present method was obviously superior in sensitivity, specificity and practical applicability. It could be expected that this work could largely promote the future studies in BH4-related fields.

Quantification of menadione from plasma and urine by a novel cysteamine-derivatization based UPLC-MS/MS method.

Menadione, as the crucial component of vitamin Ks, possessed significant nutritional and clinical values. However, there was still lack of favourable quantification strategies for it to date. For improvement, a novel cysteamine derivatization based UPLC-MS/MS method was presented in this work. The derivatizating reaction was proved non-toxic, easy-handling and high-efficient, which realized the MS detection of menadione under positive mode. Benefitting from the excellent sensitivity of the derivatizating product as well as the introduction of the stable isotope dilution technique, the quantification could be achieved in the range of 0.05-50.0ng/mL for plasma and urine matrixes with satisfied accuracy and precision. After analysis of the samples from healthy volunteers after oral administration of menadione sodium bisulfite tablets, the urinary free menadione was quantified for the very first time. We believe the progress in this work could largely promote the exploration of the metabolic mechanism of vitamin K in vivo.