In the theme of quantitative LC–MS bioanalysis of oligonucleotides free of ion-pairing, a 22-mer RNA oligonucleotide took center stage. The focus was on a unique polar-based retention scheme to ...produce a high-recovery extraction presenting a high-performance alternative extraction means, also there was the opportunity to involve hydrophilic-interaction liquid chromatography and contemporary high-resolution MS as the end point.
Original LC–MS methodology was developed for the oligonucleotide and the performance was robust for both nominal and accurate mass detection, the latter affording 10× improvement in sensitivity and 4000-fold linear dynamic range, 500 pM to 2000 nM.
A novel means of solid-phase extraction is exhibited within a robust pair-free methodology, reaching pM sensitivity with the demonstrably beneficial accurate mass platform.
The reliably accurate and precise quantification of biomarkers is a priceless objective in the drug development and diagnostic arenas. To employ a technique that brings such reliability and ...furthermore involves a simpler, faster, and inexpensive regime would only underline the potential importance of the concept and technique. To the existing established approaches for biomarker quantification in bioanalytical LC–MS, surrogate matrix (SUR-M) and surrogate analyte (SUR-A), in this Letter we present an approach that fulfills the aforementioned advantages. The concept builds on the historic method of standard addition (SA), in which one source of biological matrix is spiked with analyte to form a calibration curve. With the SA curve back-calculated, the heart of this procedure is the subsequent adjustment of the intercept to zero, the origin, and using only the slope of the curve for interpolation giving calculated sample concentrations. In SA, the concentration axis intercept indicates the endogenous analyte concentration, and our zeroing of this is equivalent to removing the endogenous level. This key shift of the calculated line to the origin unveils our novel origin-adjusted (OA) approach. It enables use akin to a regular xenobiotic method, with no need to ultimately account for the endogenous analyte level in the control matrix used for calibrants. We present a comparison of OA against the control approach of SUR-M in a representative application for kynurenine and tryptophan in human plasma by LC–MS. A numerical performance analysis performed is demonstrative of equivalence between the two approaches for both analytes.
Using CMS, it must be borne in mind that, besides the microsampling related increased challenge of sensitivity for a given instrument due to the lower sample volume available, any propensity for ...nonspecific binding to glass must be carefully investigated and mediated as the capillary surface area in contact with sample is clearly pronounced, and frozen storage will exacerbate this phenomenon. Ion mobility-based selectivity gets mobile Ion mobility, specifically exploiting differential mobilities in specialized cells for gas phase ion separation immediately prior to mass spectral detection, is another valuable analytical tool which has seen development in quantitative bioanalytical applications over the decade. ...as the industry moves further into developing biologics as therapeutic candidates, especially larger biologics that readily charges to great extents, the value of high resolution MS in detection rises dramatically (36). ...we have been given more than enough reason to celebrate the technological progression that has accompanied the first 10 years of Bioanalysis, and I look forward to the next decade with keen anticipation, all the while looking to the same primary literary source of appealing, user-friendly and contemporary nature.
Towards the stabilization of the relevant antibodies, receptors, targets, synthetic peptides and oligonucleotides, as appropriate, the array of different reagents is just part of the foundation for ...reliable ligand-binding assay performance (1) and enough subject matter to make inclusion in this article unfeasible. Care must be taken, therefore, to assign the appropriate lifetimes to mobile phase components, washes and any isolated solvent or combination of solvents used in sample preparation or analysis. Buffer solutions, although wonderfully useful in quantitative LC-MS, are very often excellent growth media for microbes (2), as a consequence of the inherent dilute salt content. For protic organic solvents in the presence of carboxylic acids, ester formation may occur (3), and in the presence of esters, hydrolysis to the free acid can occur, especially when catalyzed by acidic or basic conditions.
The National Institute of Standards and Technology (NIST) conducted an extensive investigation of the collapse of World Trade Center towers (WTC 1 and WTC 2) and the WTC 7 building. This paper ...describes the component, subsystem, and global analyses performed for the reconstruction of the structural response of WTC buildings 1, 2, and 7 to impact and fire damage. To illustrate the component and subsystem analyses, the approach taken for simulating the performance of concrete slabs and shear stud connectors in composite floors subject to fire conditions are presented, as well as steel floor framing connections for beams and girders. The development of the global models from the component and subsystem analyses is briefly described, including the sets of input data used to bound the probable conditions of impact and fire damage. The final analysis results that were used to develop the probable collapse hypotheses, and a comparison of the results against observed events, are presented for each building. A review of research activities focused on improving understanding of structural system response to multi-floor fires following the WTC disaster is also provided.
Reliable quantitative LC–MS methodology has been established and validated for an oligonucleotide in plasma in a fresh and unique fashion, free of ion-pairing reagents and the various associated ...deleterious effects from primary solution preparation through sample preparation and extraction to the LC–MS analytical end point, offering a highly selective mixed-mode solid-phase extraction with hydrophilic-interaction liquid chromatography as the chromatographic element prior to SRM detection.
Inter- and intra-assay accuracy and precision ranged from 97.9 to 111% and 2.75 to 9.66%, respectively. Recoveries of 50% were attained, and there was no significant matrix effect manifestation.
The method demonstrated rugged performance and reliability under the optimized conditions, indicating a possible exciting new avenue, free of ion-pairing, for general application in oligonucleotide quantitative LC–MS.
The National Institute of Standards and Technology (NIST) conducted an extensive investigation of the collapse of World Trade Center towers (WTC 1 and WTC 2) and the WTC 7 building. This paper ...describes the reconstruction of impact damage to each of the WTC buildings, as well as analytical studies related to the WTC building collapses. In addition, data and evidence that were collected, tests of the floor truss systems in the WTC towers that were conducted, the overall structural analysis approach, and the development of the collapse hypotheses are discussed to provide a basis for the impact analyses and the fire and structural response analyses in a companion paper. Three companion papers address the primary structural systems of the WTC towers and WTC 7, the effects of fire on the three buildings, and how these events contributed to building collapse. The papers provide an overview of the complex and extensive investigations undertaken by NIST at a level of detail that has scientific merit but presents key aspects from the voluminous official reports at a level suitable for the technical literature. The aircraft impact damage to structural members and their passive fire protection in WTC 1 and 2 were estimated through detailed aircraft impact simulations. The impact damage to WTC 7 was estimated from photographs after the collapse of WTC 1, where falling debris damaged the southwest corner of WTC 7. Based on the aircraft impact simulation, over half of the exterior columns on the north face of WTC 1 were severed and approximately 20% of the core columns were severed or heavily damaged. Spray-applied fire resistive material (SFRM) was dislodged by direct debris impact over five floors (Floors 94 to 98). WTC 2 structural damage was concentrated on the east side of the building. Over half of the exterior columns on the south face were severed and approximately 25% of the core columns were severed or heavily damaged. SFRM was dislodged by direct debris impact over six floors (Floors 78 to 83). WTC 7 was structurally damaged by debris from the collapse of WTC 1. Photographic evidence showed that seven exterior columns were severed near the southwest corner at the lower floors. Unlike the towers, the SFRM in WTC 7 likely remained intact except for local areas around the debris impact damage at the southwest corner. All three buildings were stable with the impact damage, but the WTC 2 building section above the aircraft impact damage leaned to the east and south.
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