accurate mass

(redirected from exact mass)

accurate mass

The mass of an ion of specified isotopic composition, which is calculated by summing the exact masses of the constituent atoms. The empirical formula of an ion can be deduced from the measured accurate mass of the ion if the ion mass is low enough to limit the number of formulaic possibilities and if the exact mass value is accurately known.
References in periodicals archive ?
Contract notice: Supply of 1 hplc / ms q-tof system, Liquid chromatograph coupled to exact mass spectrophotometer with quadrupole-time of flight.
Although situated nearly 13,000 light-years away, the celestial body has the exact mass as Earth and even orbits its star, in the same distance as our planet orbits the Sun.
In most cases, it is very difficult to discern the exact mass acting as a lead point.
This is where the limitation associated by the uncertainty principle of knowing simultaneously the exact mass and de cay time of a particle still remains.
The molecule's average mass was slightly higher than the exact mass due to the isotopic distribution, giving an M+1 ion one amu higher.
This new high-performance instrumentation, combined with exact mass libraries and screening tools from Agilent's MassHunter Workstation Software, provides scientists with a new level of confidence in library searching and a more efficient means to screen samples for both known and unknown compounds.
Note that the individual peaks in a mass spectrum are not some Gaussian curve shape as in most techniques, but exact mass value lines, and that the instrument resolution can be sufficient to differentiate even isotopic differences.
However, when the Stuxnet virus is used (by Iran's enemies) C* or explosives are stashed in the devices, they give truthful and honest reports on the number of centrifuge machines, exact mass of the uranium C* and everything else which is visible in the vicinity," Abbasi said.
They were first detected 25 years later, but their exact mass remains unknown.
Together, these features provide a new dimension of high-resolution, exact mass, and quantitative performance available at acquisition rates that are compatible with UPLC separations, according to the company.
Calculating this exact mass depends on our knowledge of nuclear and stellar physics, but is thought to be around 100 to 120 solar masses for stars that have formed recently in our Milky Way Galaxy.
Mass defect refers to the difference between the exact mass of an element (or a compound) and its closest integer value (Table I).