Although steroid hormones have been measured, primarily in urine, by gas chromatography–mass spectrometry (GC–MS) assays for many years, in the past decade both clinical and research laboratories ...have dramatically increased usage of liquid chromatography–tandem mass spectrometry (LC–MS/MS) assays for measuring circulating levels of steroid hormones. Because of their high validity and throughput, mass spectrometry (MS) assays have replaced conventional radioimmunoassays (RIAs) and direct immunoassays for steroid hormones in larger reference laboratories, and they are touted to become the “gold standard” for steroid hormone quantitation. These advances in MS assays present several major challenges, which include the affordability of smaller laboratories to purchase MS instruments and pay for related operating costs; improving assay sensitivity, especially for measuring low estradiol levels in postmenopausal women and women treated with aromatase inhibitors; developing assays for quantitating profiles of steroid hormone metabolites in serum and tissues; standardizing steroid MS assays; and obtaining reliable reference intervals. The present review discusses the advantages of MS assays over conventional RIAs and direct immunoassays in steroid hormone measurements, and points out some of the important challenges facing the rapid increase in usage of MS assays.
The recent onslaught of mass spectrometry (MS) to measurements of steroid hormones, including demands that they should be the only acceptable method, has confused clinicians and scientists who have ...relied for more than 40 years on a variety of immunoassay (IA) methods in steroid hormone measurements. There is little doubt that MS methods with their superior specificity will be the future method of choice in many clinical and research applications of steroid hormone measurement. However, the majority of steroid measurements are currently, and will continue to be, carried out using various types of IAs for several reasons, including their technical ease, cost and availability of commercial reagents. Speedy replacement of all IAs with MS is an unrealistic and unnecessary goal, because the availability of MS measurements is limited by cost, need of expensive equipment, technical demands and lack of commercial applications. Furthermore, IAs have multiple well-known advantages that vindicate their continuing use. The purpose of this article is to elucidate the advantages and limitations of the MS and IA techniques from two angles, i.e. promotion of MS and defence of IA. The purpose of the text is to give the reader an unbiased view about the current state and future trends of steroid analysis and to help him/her choose the correct assay method to serve his/her diagnostic and research needs.
Mass spectrometry imaging (MSI) is a powerful, label-free technique that provides detailed maps of hundreds of molecules in complex samples with high sensitivity and subcellular spatial resolution. ...Accurate quantification in MSI relies on a detailed understanding of matrix effects associated with the ionization process along with evaluation of the extraction efficiency and mass-dependent ion losses occurring in the analysis step. We present a critical summary of approaches developed for quantitative MSI of metabolites, lipids, and proteins in biological tissues and discuss their current and future applications.
The cyclization of di-(2,6-difluorophenyl)maleindinitrile with magnesium(II) and zinc(II) acetates in boiling ethylene glycol is applied to synthesize Mg(II) and Zn(II) complexes of the ...octa-(2,6-difluorophenyl)tetraazaporphyrin. The compounds are identified by UV-Vis, sup.1H NMR, and mass spectrometry methods. A comparative analysis is performed of the spectral-luminescent properties of magnesium and zinc octaaryltetraazaporphyrinates and their dependence on the number and position of the fluorine atoms in the macrocycle phenyl fragments. The DFT method is used to optimize the geometry of the synthesized complexes. Machine learning methods and QSPR are applied to predict the Soret band wavelength in the UV-V is spectra of the complexes described.
Advances in drugs of abuse testing Tamama, Kenichi
Clinica chimica acta,
March 2021, 2021-Mar, 2021-03-00, 20210301, Letnik:
514
Journal Article
Recenzirano
•Saliva, sweat, hair, and meconium are emerging types of specimen for drug testing.•LC-MSMS becomes a new gold standard for confirmatory drug testing.•LC-hybrid-Tof-MS is usable for comprehensive ...drug screening.•Miniature ambient ionization MS can quickly analyze biological specimens.•Miniature ambient ionization MS is promising for rapid drugs of abuse testing.
Drugs of abuse testing is widely used clinically and forensically. Urine is the preferred type of specimen for drugs of abuse screening, but saliva, sweat, hair, and meconium are emerging types of specimens. GC–MS has been used as a gold standard for confirmatory drug testing, but LC-tandem-MS can analyze more diverse types of analytes than GC–MS. Thus, LC-tandem-MS becomes a new gold standard for confirmatory drug testing. Unlike GC–MS, LC-tandem-MS is not suited for non-targeted comprehensive drug screening. But with the advent of high-resolution-MS such as Tof-MS, which can discriminate the compounds of similar molecular masses but with different formulas, LC-hybrid-Tof-MS is usable for non-targeted comprehensive drug screening. Another technical advancement is the advent of miniature ambient ionization MS, which can analyze biological specimens including urine within one minute. Thus these mass spectrometers are promising for rapid drugs of abuse testing in a POC setting.
Reaction of YbCpsub.2(dme) (Cp = cyclopentadienyl, dme = 1,2 dimethoxyethane) with bis(diphenylphosphano)methane dioxide (Hsub.2dppmOsub.2) leads to deprotonation of the ligand Hsub.2dppmOsub.2 and ...oxidation of ytterbium, forming an extremely air-sensitive product, Ybsup.III(HdppmOsub.2)sub.3 (1), a six-coordinate complex with three chelating (OPCHPO) HdppmOsub.2 ligands. Complex 1 was also obtained by a redox transmetallation/protolysis synthesis from metallic ytterbium, Hg(Csub.6Fsub.5)sub.2, and Hsub.2dppmOsub.2. In a further preparation, the reaction of Yb(Csub.6Fsub.5)sub.2 with Hsub.2dppmOsub.2, not only yielded compound 1, but also gave a remarkable tetranuclear cage, Ybsub.4(µ-HdppmOsub.2)sub.6(µ-F)sub.6 (2) containing two Yb(µ-F)sub.2 rhombic units linked by two fluoride ligands and the tetranuclear unit is encapsulated by six bridging HdppmOsub.2 donors. The fluoride ligands of the cage result from C-F activation of pentafluorobenzene and concomitant formation of p-Hsub.2Csub.6Fsub.4 and m-Hsub.2Csub.6Fsub.4, the last being an unexpected product.
Native mass spectrometry (MS) is becoming an important integral part of structural proteomics and system biology research. The approach holds great promise for elucidating higher levels of protein ...structure: from primary to quaternary. This requires the most efficient use of tandem MS, which is the cornerstone of MS-based approaches. In this work, we advance a two-step fragmentation approach, or (pseudo)-MS3, from native protein complexes to a set of constituent fragment ions. Using an efficient desolvation approach and quadrupole selection in the extended mass-to-charge (m/z) range, we have accomplished sequential dissociation of large protein complexes, such as phosporylase B (194 kDa), pyruvate kinase (232 kDa), and GroEL (801 kDa), to highly charged monomers which were then dissociated to a set of multiply charged fragmentation products. Fragment ion signals were acquired with a high resolution, high mass accuracy Orbitrap instrument that enabled highly confident identifications of the precursor monomer subunits. The developed approach is expected to enable characterization of stoichiometry and composition of endogenous native protein complexes at an unprecedented level of detail.
Orthorhombic phases for perovskite solar cellsThe power conversion efficiencies (PCEs) of all-inorganic perovskites are lower than those of materials with organic cations. This is in part because ...these materials have larger bandgaps. The cubic crystal phases of these materials also exhibit poor stability. Wang et al. synthesized the orthorhombic β-phase of CsPbI3 from HPbI3 and CsI. The material exhibited higher stability and a more favorable bandgap, which allowed for PCEs of 15%. Passivation of the surface trap state with choline iodide boosted PCEs to 18%.Science, this issue p. 591Although β-CsPbI3 has a bandgap favorable for application in tandem solar cells, depositing and stabilizing β-CsPbI3 experimentally has remained a challenge. We obtained highly crystalline β-CsPbI3 films with an extended spectral response and enhanced phase stability. Synchrotron-based x-ray scattering revealed the presence of highly oriented β-CsPbI3 grains, and sensitive elemental analyses—including inductively coupled plasma mass spectrometry and time-of-flight secondary ion mass spectrometry—confirmed their all-inorganic composition. We further mitigated the effects of cracks and pinholes in the perovskite layer by surface treating with choline iodide, which increased the charge-carrier lifetime and improved the energy-level alignment between the β-CsPbI3 absorber layer and carrier-selective contacts. The perovskite solar cells made from the treated material have highly reproducible and stable efficiencies reaching 18.4% under 45 ± 5°C ambient conditions.
PDF
