Mass and intensity calibration of gas chromatograph/mass spectrometer (GC/MS) responses is an important quality assurance issue for chemical analysis. Ion abundance calibration with decafluorotriphenylphosphine (DFTPP) was applied in 1975 to standardize quadrupole spectra to resemble the ion abundances that were obtainable from magnetic sector mass spectrometers. Modern quadrupole mass spectrometers provide significantly greater high-mass sensitivity than allowed under the 1975 study. Thus, those recommendations were reevaluated with 2 approaches. First, an interlaboratory study was conducted using 15 different gas chromatography/mass spectrometry (GC/MS) systems. Second, the U.S. Environmental Protection Agency Contract Laboratory Program (EPA-CLP) quality assurance data base was searched and over 6500 DFTPP tune results were plotted and evaluated. Based on these approaches, updated ion abundance criteria recommendations have been developed, which contemporary instruments can meet, and which meet data quality objectives regarding identification and quantitative analysis of analytes.
Download full-text PDF |
Source |
|---|
Publication Analysis
Top Keywords
Similar Publications
Entropy engineering activation of UiO-66 for boosting catalytic transfer hydrogenation.
Nat Commun
January 2025
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, 130012, Changchun, P. R. China.
High-entropy metal-organic frameworks (HE-MOFs) hold promise as versatile materials, yet current rare examples are confined to low-valence elements in the fourth period, constraining their design and optimization for diverse applications. Here, a novel high-entropy, defect-rich and small-sized (32 nm) UiO-66 (ZrHfCeSnTi HE-UiO-66) has been synthesized for the first time, leveraging increased configurational entropy to achieve high tolerance to doping with diverse metal ions. The lattice distortion of HE-UiO-66 induces high exposure of metal nodes to create coordination unsaturated metal sites with a concentration of 322.
View Article and Find Full Text PDFBasic Science and Pathogenesis.
Alzheimers Dement
December 2024
Emory University School of Medicine, Atlanta, GA, USA.
Background: The extracellular amyloid plaques, one of the pathological hallmarks of Alzheimers Disease (AD), are frequently also observed in the cortex of cognitively unimpaired subjects or as co-pathology in other neurodegenerative diseases. Progressive deposition of fibrillar amyloid-β (Aβ) as amyloid plaques for two decades prior disease onset leads to extensive isomerization of Aβ N-terminus. Quantifying the extent of isomerized Aβ can be provide insight into the different stages of amyloidosis in the brain.
View Article and Find Full Text PDFBackground: Neuropathologic inclusions formed by hyperphosphorylated protein tau in the brain are a hallmark of Alzheimer's disease and other human neurodegenerative disorders commonly referred to as tauopathies. Tau lesions differ in their disease-specific morphological presentations, affected cell type, subcellular compartments and tau isoforms present in the inclusions. In addition, tau filaments isolated from different tauopathies have distinct fibrillar structures that potentially underlie the morphological diversity of tau lesions.
View Article and Find Full Text PDFGenerating Strong Metal-Support Interaction and Oxygen Vacancies in Cu/MgAlO Catalysts by CO Treatment for Enhanced CO Hydrogenation to Methanol.
ACS Appl Mater Interfaces
January 2025
Department of Chemical Engineering, and Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion (MATEC), Guangdong Technion Israel Institute of Technology (GTIIT), Guangdong 515063, China.
Strong metal-support interactions (SMSIs) are essential for optimizing the performance of supported metal catalysts by tuning the metal-oxide interface structures. This study explores the hydrogenation of CO to methanol over Cu-supported catalysts, focusing on the synergistic effects of strong metal-support interaction (SMSI) and oxygen vacancies introduced by the CO treatment to the catalysts on the catalytic performance. Cu nanoparticles were immobilized on Mg-Al layered double oxide (LDO) supports and modified with nitrate ions to promote oxygen vacancy generation.
View Article and Find Full Text PDFNickel-Doping Induced Oxygen Vacancies in MnO Hollow Cube with Enlarged Interlayer Spacing for Stable Sodium Ions Storage.
Small
January 2025
School of Chemistry, South China Normal University, Guangzhou, 510006, P. R. China.
Intrinsic low conductivity, poor structural stability, and narrow interlayer spacing limit the development of MnO in sodium-ion (Na) supercapacitors. This work constructs the hollow cubic Mn-PBA precursor through an ion-exchange process to in situ obtain a hollow cubic H-Ni-MnO composite with Ni doping and oxygen vacancies (O) via a self-oxidation strategy. Experiments and theoretical calculations show that the hollow nanostructure and the expanding interlayer spacing induced by Ni doping are beneficial for exposing more reactive sites, synergistically manipulating the Na transport pathways.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!