A critical review of the proposed definitions of fundamental chemical quantities and their impact on chemical communities (IUPAC Technical Report)

In the proposed new SI, the kilogram will be redefined in terms of the Planck constant and the mole will be redefined in terms of the Avogadro constant. These redefinitions will have some consequences for measurements in chemistry. The goal of the Mole Project (IUPAC Project Number 2013-048-1-100) was to compile published work related to the definition of the quantity \u2018amount of substance\u2019, its unit the \u2018mole\u2019, and the consequence of these definitions on the unit of the quantity mass, the kilogram. The published work has been reviewed critically with the aim of assembling all possible aspects in order to enable IUPAC to judge the adequateness of the existing definitions or new proposals. Compilation and critical review relies on the broadest spectrum of interested IUPAC members.Peer reviewed: YesNRC publication: Ye

Determination of selenium‑containing species, including nanoparticles, in selenium‑enriched Lingzhi mushrooms

Ministerio de Ciencia e Innovación [PID2019-104334RB-I00, PID2021-123854OB-I00]; Spanish MICINN (Spanish Ministry for Science and Innovation) [SV-PA-21-AYUD/2021/51399]; FICYT; Thermo Fisher Scientific (Bremen, Germany

Blank correction in isotope dilution

A novel method for compensation of the procedural blank in isotope dilution is presented. This method - entitled "blank-matching" - copes with the blank through experimental design. Both sample and calibration solutions are exposed to the same amount of isotopic standard and same procedural blank. The identical treatment of sample and calibrators eliminates the need for subtracting the procedural blank from the result obtained by isotope dilution. A further advantage of the method is that quantitation of the analyte in the procedural blank is not required. Blank-matching is simple and fast to implement and it permits direct determination of results without further corrections. This aspect has an important metrological outcome: blank-matching isotope dilution can be considered a primary method of analysis that does not involve the procedural blank as a potential source of bias.Peer reviewed: YesNRC publication: Ye

Mass Spectrometric Separation and Quantitation of Overlapping Isotopologues. Deuterium Containing Hydrides of As, Sb, Bi, Sn, and Ge

Mass spectra of fully and partially deuterated As, Sb, Bi, Ge, and Sn hydrides have been obtained using several mathematical approaches aimed at signal extraction and reconstruction. Study of such hydride mixtures is important for the elucidation of hydride generation mechanisms. In this approach, mass spectra of partially deuterated isotopomers, i.e., AsH2D and AsHD2, are extracted using the weighted two-band target entropy minimization method. Alternatively, these mass spectra were constructed from the mass spectra of fully deuterated and hydrogenated hydrides using the statistical approach in fragmentation pathways. Concentration profiles of all deuterated hydrides were obtained from their overlapping mixture mass spectra using least-squares deconvolution

Mass Spectrometric Separation and Quantitation of Overlapping Isotopologues. H2O/HOD/D2O and H2Se/HDSe/D2Se Mixtures

Three conceptually different mathematical methods are presented for accurate mass spectrometric determination of H2O/HOD/D2O and H2Se/HDSe/D2Se concentrations from mixtures. These are alternating least-squares, weighted two-band target entropy minimization, and a statistical mass balance model. The otherwise nonmeasurable mass spectra of partially deuterated isotopologues (HOD and HDSe) are mathematically constructed. Any recorded isotopologue mixture mass spectra are then deconvoluted by least-squares into their components. This approach is used to study the H2O/D2O exchange reaction, and is externally validated gravimetrically. The H2O/D2O exchange equilibrium constant is also measured from the deconvoluted 70 eV electron impact GC/MS data (K = 3.85 ± 0.03)