geologia: Helium

Evidence: 100 • authority: 72

Helium (from Ancient Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements, and it does not have a melting point at standard pressures. It is the second-lightest and second-most abundant element in the observable universe, after hydrogen. It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and Jupiter, because of the very high nuclear bindin…

Evidence: 51 • authority: 92

Quantification of 24 Inorganic Impurities in Vismodegib and Idelalisib Anti-Cancer Drug Substances by Using ICP-MS.. Background Metal impurities in pharmaceutical products can originate from various sources, including manufacturing machinery, catalysts used during drug synthesis, and even the container-closure systems. Objective The objective of the present study is to accurately quantify trace levels of 24 metal impurities in the active pharmaceutical ingredients of the anticancer drugs vismodegib and idelalisib using an inductively coupled plasma mass spectrometer. Method The diluent used in the analysis consists of a mixture of 3% nitric acid and 1% hydrochloric acid, while argon serves…

Evidence: 45 • authority: 72

Atomic mass (ma or m) is the mass of a single atom. The atomic mass mostly comes from the combined mass of the protons and neutrons in the nucleus, with minor contributions from the electrons and nuclear binding energy. The atomic mass of atoms, ions, or atomic nuclei is slightly less than the sum of the masses of their constituent protons, neutrons, and electrons, due to mass defect (explained by mass–energy equivalence: E = mc2). Atomic mass is often measured in dalton (Da) (a.k.a. unified atomic mass unit (u)). One dalton is equal to ⁠+1/12⁠ the mass of a carbon-12 atom in its natural state, given by the atomic mass constant mu = m(12C)/12 = 1 Da, where m(12C) is the atomic mass of carbo…

Evidence: 42 • authority: 72

In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-dark) matter in the universe is either hydrogen or helium, and astronomers use the word metals as convenient shorthand for all elements except hydrogen and helium. This word-use is distinct from the conventional chemical or physical definition of a metal as an electrically conducting element. Stars and nebulae with relatively high abundances of heavier elements are called metal-rich in discussions of metallicity, even though many of those elements are called nonmetals in chemistry. The presence of heavier elements is the res…

Evidence: 34 • authority: 72

The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction. Volume fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is similar in value to molecular mole fraction for gas mixtures at relatively low densities and pressures, and ideal gas mixtures. Most abundance values in this article are given as mass fractions. The abundance…

Evidence: 27 • authority: 72

The standard atomic weight of a chemical element (symbol Ar°(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, isotope 63Cu (Ar = 62.929) constitutes 69% of the copper on Earth, the rest being 65Cu (Ar = 64.927), so A r ° ( 29 Cu ) = 0.69 × 62.929 + 0.31 × 64.927 = 63.55. {\displaystyle A_{\text{r}}{\text{°}}(_{\text{29}}{\text{Cu}})=0.69\times 62.929+0.31\times 64.927=63.55.} Relative isotopic mass is dimensionless, and so is the weighted average. It can be converted into a measure of mass (with dimension M) by multiplying it with the atomic mass constant dalton. Am…

Evidence: 27 • authority: 92

Characterizing the Elemental Metabolome in Asparagus officinalis with Multielemental Speciation Analysis.. We report a multielemental and quantitative speciation analysis study with chromatographic inductively coupled plasma-mass spectrometry (ICP-MS/MS) detection involving four elements (sulfur, selenium, arsenic, and phosphorus) in Asparagus officinalis. The samples were locally purchased and labeled to originate from different regions in two continents. Major compounds were identified and quantified with confirmation based on chemical synthesis in pure form. Nontargeted analysis revealed significant quantitative and qualitative variation for the elemental metabolomes among samples, parti…

Evidence: 27 • authority: 92

Development and Validation of an ICP-MS/MS Method for Multi-elemental Analysis of Human Hair with Application to Heart Failure.. Human hair has emerged as a promising non-invasive matrix for assessing long-term exposure to essential and toxic trace elements relevant to cardiovascular disease. However, its clinical applicability depends on the availability of robust and fully validated analytical methodologies capable of overcoming matrix-related challenges. This study aimed to develop and validate a reliable and high-throughput method for multi-elemental (As, Cd, Cu, Pb, Se and Zn) analysis of human hair using microwave-assisted acid digestion followed by ICP-MS/MS, and to explore its poten…

Evidence: 25 • authority: 80

Review for "Three combustion reactions in a single elemental analysis and isotope ratio mass spectrometry acquisition as a strategy to save helium and energy"

Evidence: 25 • authority: 80

Decision letter for "Sulfur isotope analyses using 3× elemental analysis/isotope ratio mass spectrometry: Saving helium and energy while reducing analytical time and costs"

Evidence: 25 • authority: 80

Review for "Sulfur isotope analyses using 3× elemental analysis/isotope ratio mass spectrometry: Saving helium and energy while reducing analytical time and costs"

Evidence: 25 • authority: 80

Review for "Sulfur isotope analyses using 3× elemental analysis/isotope ratio mass spectrometry: Saving helium and energy while reducing analytical time and costs"