An electron-capture negative chemical ionization (NCI) gas chromatography-mass spectrometry (GC-MS) method for determination of lead (Pb) in blood samples is described. Extraction of Pb from the sample does not involve hot digestion but is based on treatment at ambient temperature. The blood sample is supplemented with a known amount of internal standard (204Pb) for isotope dilution and is trea...

For the first time, an interlaboratory comparison was performed in the field of quantitative metabolite profiling in Pichia pastoris. The study was designed for the evaluation of different measurement platforms integrating different quantification strategies using internal standardization. Nineteen primary metabolites including amino acids and organic acids were selected for the study. Homogeno...

Neutron activation analysis with an internal standard correction was applied to the determination of Cr and Co in a ceramics certified reference material (NMIJ CRM 8004-a silicon nitride powder). Cesium was used as an internal standard to compensate for any inhomogeneity of the neutron flux through an irradiation capsule and to improve the repeatability of gamma-ray measurements. It was found t...

The emergence of homeostatic mechanisms that enable maintenance of an intracellular steady state during growth was critical to the advent of cellular life. Here, we show that concentration-dependent reversible binding of short oligonucleotides, of both specific and random sequence, can modulate ribozyme activity. In both cases, catalysis is inhibited at high concentrations, and dilution activat...

We investigated the effects of dilution of plasma samples on the measured concentrations of catecholamines. Diluting samples of human plasma 10-, 50-, and 100-fold with Tris buffer (100 mol/L, pH 8.6) improved analytical recovery of internal standards, suggesting that it decreases the commonly observed inhibition of methylation in radioenzymatic assays of catecholamines in plasma. However, the ...

The effect of the growth rate and oxygen transfer rate on Debaryomyces hansenii physiology was studied using xylose-limited and oxygen-limited chemostat cultures respectively, and complemented with enzymatic assays. Under xylose-limited chemostat (oxygen-excess) neither ethanol nor xylitol was produced over the entire range of dilution rate (D). The maximal volumetric biomass productivity was 2...

Abstract In the context of CO2 challenge, oxy-fuel combustion in internal engines (OFC-ICE) arises as a promising technology for carbon capture and almost zero-NOx solutions. Although literature shows some experimental theoretical works on OFC-ICE, there is lack systematic studies dealing with dilution strategies or where non-synthetic EGR used. Using combination 0D-1D CFD modeling measurements...

A stable isotopically labeled (SIL) analogue is believed to be the most appropriate internal standard in a quantitative bioanalytical liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay. It is assumed that a SIL internal standard always compensates for variability in chemical derivatization, sample extraction and LC/MS/MS analysis due to its nearly identical chemical and physical pr...