The steroid disulfates ( bis-sulfates) are a significant but minor fraction of the urinary steroid metabolome that have not been widely studied because major components are not hydrolyzed by the commercial sulfatases commonly used in steroid metabolomics. In early studies, conjugate fractionation followed by hydrolysis using acidified solvent (solvolysis) was used for the indirect detection of this fraction by GC-MS. This paper describes the application of a specific LC-MS/MS method for the direct identification of disulfates in urine, and their use as markers for the prenatal diagnosis of disorders causing reduced estriol production: STSD (steroid sulfatase deficiency), SLOS (Smith-Lemli-Opitz syndrome) and PORD (P450 oxidoreductase deficiency). Disulfates were detected by monitoring a constant ion loss (CIL) from the molecular di-anion. While focused on disulfates, our methodology included an analysis of intact steroid glucuronides and monosulfates because steroidogenic disorder diagnosis usually requires an examination of the complete steroid profile. In the disorders studied, a few individual steroids (as disulfates) were found particularly informative: pregn-5-ene-3β,20-diol, pregn-5-ene-3β,21-diol (STSD, neonatal PORD) and 5α-pregnane-3β,20-diol (pregnancy PORD). Authentic steroid disulfates were synthesized for use in this study as aid to characterization. Tentative identification of 5ξ-pregn-7-ene-3ξ,20-diol and 5ξ-pregn-7-ene-3ξ,17,20-triol disulfates was also obtained in samples from SLOS affected pregnancies. Seven ratios between the detected metabolites were applied to distinguish the three selected disorders from control samples. Our results show the potential of the direct detection of steroid conjugates in the diagnosis of pathologies related with steroid biosynthesis.

Doubly or bisconjugated steroid metabolites have long been known as minor components of the steroid profile that have traditionally been studied by laborious and indirect fractionation, hydrolysis and gas chromatography-mass spectrometry (GC-MS) analysis.Recently, the synthesis and characterisation of steroid bis(sulfate) (aka disulfate or bissulfate) reference materials enabled the liquid chromatography-tandem mass spectrometry (LC-MS/MS) study of this metabolite class and the development of a constant ion loss (CIL) scan method for the direct and untargeted detection of steroid bis(sulfate) metabolites. Methods for direct LC-MS/MS detection of other bisconjugated steroids, such as steroid bisglucuronide and mixed steroid sulfate glucuronide metabolites, have great potential to reveal a more complete picture of the steroid profile. However, access to steroid bisglucuronide or sulfate glucuronide reference materials necessary for LC-MS/MS method development, metabolite identification or quantification is severely limited. In this work, ten steroid bisglucuronide and ten steroid sulfate glucuronide reference materials were synthesised through an ordered combination of chemical sulfation and/or enzymatic glucuronylation reactions. All compounds were purified and characterised using NMR and MS methods. Chemistry for the preparation of stable isotope labelled steroid { 13 C 6 }glucuronide internal standards has also been developed and applied to the preparation of two selectively mono-labelled steroid bisglucuronide reference materials used to characterise more completely MS fragmentation pathways. The electrospray ionisation and fragmentation of the bisconjugated steroid reference materials has been studied.Preliminary targeted ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis of the reference materials prepared revealed the presence of three steroid sulfate glucuronides as endogenous human urinary metabolites.Highlights  Ten steroid bisglucuronide reference materials synthesised and characterised  Ten steroid sulfate glucuronide reference materials synthesised and characterised  Stable isotope labelled internal standards using 18 O and 13 C prepared  Electrospray ionisation and fragmentation of reference materials studied  Three steroid sulfate glucuronide metabolites confirmed in human urine Keywords:Steroid bisglucuronide; steroid sulfate glucuronide; steroid conjugate; phase II metabolism; stable isotope labelled internal standard; mass spectrometry. AbbreviationsCID = collision induced dissociation, CIL = constant ion loss, DHEA = dehydroepiandrosterone, EA = epiandrosterone, E. coli = Escherichia coli, GC-MS = gas chromatography-mass spectrometry, LC-MS = liquid chromatography-mass spectrometry, LC-MS/MS = liquid chromatography-tandem mass spectrometry, NL = neutral loss, PORD = cytochrome P450 Oxido-Reductase Deficiency, SIM = single ion monitoring, SLOS = Smith-Lemli-Opitz Syndrome, SPE = solid phase extraction, SRM = selected reaction monitoring, STSD = Steroi...

Selective incorporation of stable isotope labelled sulfate esters in steroidal systems affords internal standards and MS probes to investigate the fragmentation patterns of mono- and bis-conjugated derivatives in CID MS/MS experiments.

The study of urinary phase II sulfate metabolites is central to understanding the role and fate of endogenous and exogenous compounds in biological systems. This study describes a new workflow for the untargeted metabolic profiling of sulfated metabolites in a urine matrix. Analysis was performed using ultra-high-performance liquid chromatography-high resolution tandem mass spectrometry (UHPLC-HRMS/MS) with data dependent acquisition (DDA) coupled to an automated script-based data processing pipeline and differential metabolite level analysis. Sulfates were identified through k-means clustering analysis of sulfate ester derived MS/MS fragmentation intensities. The utility of the method was highlighted in two applications. Firstly, the urinary metabolome of a thoroughbred horse was examined before and after administration of the anabolic androgenic steroid (AAS) testosterone propionate. The analysis detected elevated levels of ten sulfated steroid metabolites, three of which were identified and confirmed by comparison with synthesised reference materials. This included 5α-androstane-3β,17α-diol 3-sulfate, a previously unreported equine metabolite of testosterone propionate. Secondly, the hydrolytic activity of four sulfatase enzymes on pooled human urine was examined. This revealed that Pseudomonas aeruginosa arylsulfatases (PaS) enzymes possessed higher selectivity for the hydrolysis of sulfated metabolites than the commercially available Helix pomatia arylsulfatase (HpS). This novel method provides a rapid tool for the systematic, untargeted metabolic profiling of sulfated metabolites in a urinary matrix.

The identification and confirmation of steroid sulfate metabolites in biological samples are essential to various fields, including anti-doping analysis and clinical sciences. Ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) is the leading method for the detection of intact steroid conjugates in biofluids, but because of the inherent complexity of biological samples and the low concentration of many targets of interest, metabolite identification based solely on mass spectrometry remains a major challenge. The confirmation of new metabolites typically depends on a comparison with synthetically derived reference materials that encompass a range of possible conjugation sites and stereochemistries. Herein, energy-resolved collision-induced dissociation (CID) is used as part of UHPLC-HRMS/MS analysis to distinguish between regio- and stereo-isomeric steroid sulfate compounds. This wholly MS-based approach was employed to guide the synthesis of reference materials to unambiguously confirm the identity of an equine steroid sulfate biomarker of testosterone propionate administration.

Reliable drywood termite detection in structures is challenging but is critical for effective management. A microwave-based non-destructive method was evaluated for detecting termite activity. This study evaluated factors affecting the ability of this device to reliably detect Cryptotermes brevis in timber. The device displayed a high probability of successfully detecting C. brevis in naturally infested boards. The system detected termites 97% of the time when used at the highest sensitivity level, while producing few false positives. The number of termites did not affect detection ability, and detectable signals were produced even when a single termite was present. Detection success decreased with both increasing wood density and testing perpendicular to the grain in abrupt transition timber species. The device detected termites to a maximum depth of 45 mm in southern pine (Pinus spp.), but sensitivity declined with increased wood density with the detection limit declining to only 20 mm in denser Tasmanian oak (Eucalyptus spp). The device could only detect termites in samples with densities between 392 to 511 kg/m3 in 38 mm thick radiata pine samples. The results support the ability of microwaves to reliably detect C. brevis in timber.