Development of an improved standard reference material for folate vitamers in human serum.

The US National Institute of Standards and Technology (NIST) developed a Standard Reference Material® (SRM®) 3949 Folate Vitamers in Frozen Human Serum to replace SRM 1955 Homocysteine and Folate in Human Serum. The presence of increased endogenous levels of folic acid and 5-methyltetrahydrofolate (5mTHF) in SRM 3949, enhanced folate stability via addition of ascorbic acid, and inclusion of values for additional minor folates are improvements over SRM 1955 that should better serve the clinical folate measurement community. The new SRM contains folates at three levels.

The need for multicomponent gas standards for breath biomarker analysis.

Exhaled breath is a non-invasive, information-rich matrix with the potential to diagnose or monitor disease, including infectious disease. Despite significant effort dedicated to biomarker identification in case control studies, very few breath tests are established in practice. In this topical review, we identify how gas standards support breath analysis today and what is needed to support further expansion and translation to practice.

Workshop report: Toward the development of a human whole stool reference material for metabolomic and metagenomic gut microbiome measurements.

Introduction: To date, there has been little effort to develop standards for metabolome-based gut microbiome measurements despite the significant efforts toward standard development for DNA-based microbiome measurements.

Objectives: The National Institute of Standards and Technology (NIST), The BioCollective (TBC), and the North America Branch of the International Life Sciences Institute (ILSI North America) are collaborating to extend NIST's efforts to develop a Human Whole Stool Reference Material for the purpose of method harmonization and eventual quality control.

Methods: The reference material will be rationally designed for adequate quality assurance and quality control (QA/QC) for underlying measurements in the study of the impact of diet and nutrition on functional aspects of the host gut microbiome and relationships of those functions to health.

Nontargeted lipidomics of novel human plasma reference materials: hypertriglyceridemic, diabetic, and African-American.

The unavailability of appropriate quality assurance/quality control materials in many lipidomics applications poses a significant challenge for lipidomics research. It is recommended that samples with certified values and/or consensus estimates, such as NIST SRM 1950-Metabolites in Frozen Human Plasma, be implemented in routine analyses to enable community-wide comparisons of lipidomics results and analytical workflows. Herein, we applied a nontargeted lipidomics method for the analysis of a new human plasma reference material suite developed by NIST (hypertriglyceridemic, diabetic, and African-American plasma pools), in addition to SRM 1950.

Enhancing the accuracy of measurement of small molecule organic biomarkers.

Over two decades, the Organic Analysis Working Group (OAWG) of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) has organized a number of comparisons for clinically relevant small molecule organic biomarkers. The aim of the OAWG community is to be part of the coordinated international movement towards accuracy and comparability of clinical measurements that will, in turn, minimize the wastage of repeat testing and unnecessary therapy to create a sustainable healthcare industry. International and regional directives/requirements on metrological traceability of calibrators and control materials are in place.

Towards quality assurance and quality control in untargeted metabolomics studies.

We describe here the agreed upon first development steps and priority objectives of a community engagement effort to address current challenges in quality assurance (QA) and quality control (QC) in untargeted metabolomic studies. This has included (1) a QA and QC questionnaire responded to by the metabolomics community in 2015 which recommended education of the metabolomics community, development of appropriate standard reference materials and providing incentives for laboratories to apply QA and QC; (2) a 2-day 'Think Tank on Quality Assurance and Quality Control for Untargeted Metabolomic Studies' held at the National Cancer Institute's Shady Grove Campus and (3) establishment of the Metabolomics Quality Assurance and Quality Control Consortium (mQACC) to drive forward developments in a coordinated manner.

Differentiation of fentanyl analogues by low-field NMR spectroscopy.

Forensic laboratories commonly receive new psychoactive substances such as fentanyl analogues and other synthetic opioids that are difficult to identify. Slight changes to chemical structures, e.g.

The role of the CCQM OAWG in providing SI traceable calibrators for organic chemical measurements.

Metrological traceability for organic chemical measurements is a documented unbroken chain of calibrations with stated uncertainties that ideally link the measurement result for a sample to a primary calibrator in appropriate SI units (e.g., mass fraction).

A New Realization of SI for Organic Chemical Measurement: NIST PS1 Primary Standard for Quantitative NMR (Benzoic Acid).

Metrological traceability to common references supports the comparability of chemical measurement results produced by different analysts, at various times, and at separate places. Ideally, these references are realizations of base units of the International System of Units (SI). ISO/IEC 17025 (Clause 6.

A scoring metric for multivariate data for reproducibility analysis using chemometric methods.

Process quality control and reproducibility in emerging measurement fields such as metabolomics is normally assured by interlaboratory comparison testing. As a part of this testing process, spectral features from a spectroscopic method such as nuclear magnetic resonance (NMR) spectroscopy are attributed to particular analytes within a mixture, and it is the metabolite concentrations that are returned for comparison between laboratories. However, data quality may also be assessed directly by using binned spectral data before the time-consuming identification and quantification.

Unsupervised classification of petroleum Certified Reference Materials and other fuels by chemometric analysis of gas chromatography-mass spectrometry data.

As feedstocks transition from conventional oil to unconventional petroleum sources and biomass, it will be necessary to determine whether a particular fuel or fuel blend is suitable for use in engines. Certifying a fuel as safe for use is time-consuming and expensive and must be performed for each new fuel. In principle, suitability of a fuel should be completely determined by its chemical composition.

Navigating the Decision Space: Shared Medical Decision Making as Distributed Cognition.

Despite increasing prominence, little is known about the cognitive processes underlying shared decision making. To investigate these processes, we conceptualize shared decision making as a form of distributed cognition. We introduce a Decision Space Model to identify physical and social influences on decision making.

Chemical purity using quantitative H-nuclear magnetic resonance: a hierarchical Bayesian approach for traceable calibrations.

Chemical purity assessment using quantitative H-nuclear magnetic resonance spectroscopy is a method based on ratio references of mass and signal intensity of the analyte species to that of chemical standards of known purity. As such, it is an example of a calculation using a known measurement equation with multiple inputs. Though multiple samples are often analyzed during purity evaluations in order to assess measurement repeatability, the uncertainty evaluation must also account for contributions from inputs to the measurement equation.

25-Hydroxyvitamin D isomerizes to pre-25-hydroxyvitamin D in solution: considerations for calibration in clinical measurements.

Reference standards for the vitamin D metabolites 25-hydroxyvitamin D3, 25-hydroxyvitamin D2, and 3-epi-25-hydroxyvitamin D3 were evaluated using liquid chromatography (LC) with ultraviolet (UV) absorbance and mass spectrometric (MS) detection to assess purity. The chromatograms for solutions of all three 25(OH)D compounds, obtained using a pentafluorophenyl (PFP) stationary phase, revealed peaks that increased in area over time and had MS spectra that were nearly identical to the parent compound, indicating isomers had formed in solution that were unrelated to the reference standard purity. However, when the purity evaluations were completed with a cyanopropyl stationary phase, the isomeric products coeluted with the parent compounds and were not observable.

Metrological approaches to organic chemical purity: primary reference materials for vitamin D metabolites.

Given the critical role of pure, organic compound primary reference standards used to characterize and certify chemical Certified Reference Materials (CRMs), it is essential that associated mass purity assessments be fit-for-purpose, represented by an appropriate uncertainty interval, and metrologically sound. The mass fraction purities (% g/g) of 25-hydroxyvitamin D (25(OH)D) reference standards used to produce and certify values for clinical vitamin D metabolite CRMs were investigated by multiple orthogonal quantitative measurement techniques. Quantitative (1)H-nuclear magnetic resonance spectroscopy (qNMR) was performed to establish traceability of these materials to the International System of Units (SI) and to directly assess the principal analyte species.

Quantitative evidence for organic peroxy radical photochemistry at 254 nm.

Quantitative evidence is presented for the importance of alkyl peroxy photochemistry in the formation of secondary organic aerosol at 254 nm. Particles were generated by extensively oxidizing dodecanoic acid with photolytically generated hydroxyl radicals in a flow cell. The resulting particles were collected and analyzed for composition, which shows a lower contribution from multiply substituted parent molecules and much more decomposition product than expected from typical low-NOx oxidation mechanisms.

Stability of cocaine and its metabolites in municipal wastewater--the case for using metabolite consolidation to monitor cocaine utilization.

Transformations of cocaine and eleven of its metabolites were investigated in untreated municipal sewage at pH ≈ 7 and 9, 23, and 31 °C. Results indicated that hydrolysis-possibly bacterially mediated-was the principal transformation pathway. Residues possessing alkyl esters were particularly susceptible to hydrolysis, with pseudo-first-order rate constants varying from 0.

Probing the intracellular glutathione redox potential by in-cell NMR spectroscopy.

Non-invasive and real-time analysis of cellular redox processes has been greatly hampered by lack of suitable measurement techniques. Here we describe an in-cell nuclear magnetic resonance (NMR) based method for measuring the intracellular glutathione redox potential by direct and quantitative measurement of isotopically labeled glutathione introduced exogenously into living yeast. By using this approach, perturbations in the cellular glutathione redox homeostasis were also monitored as yeast cells were subjected to oxidative stress.