Lock mass, application

In tandem MS mode, because the product ions are recorded with the same TOF mass analyzers as in full scan mode, the same high resolution and mass accuracy is obtained. Isolation of the precursor ion can be performed either at unit mass resolution or at 2-3 m/z units for multiply charged ions. Accurate mass measurements of the elemental composition of product ions greatly facilitate spectra interpretation and the main applications are peptide analysis and metabolite identification using electrospray iomzation [68]. In TOF mass analyzers accurate mass determination can be affected by various parameters such as (i) ion intensities, (ii) room temperature or (iii) detector dead time. Interestingly, the mass spectrum can be recalibrated post-acquisition using the mass of a known ion (lock mass). The lock mass can be a cluster ion in full scan mode or the residual precursor ion in the product ion mode. For LC-MS analysis a dual spray (LockSpray) source has been described, which allows the continuous introduction of a reference analyte into the mass spectrometer for improved accurate mass measurements [69]. The versatile precursor ion scan, another specific feature of the triple quadrupole, is maintained in the QqTOF instrument. However, in pre-... 

The amount of energy released by the incident beam is sufficiently high in the vicinity of the point of impact that sample molecules are ionized by proton transfer from a protonated matrix. Typically, the spectrum obtained shows cluster ions formed from the matrix. In particular, the positive ion spectrum of glycerol (mw 92 u) shows a series of ions 92 +l where n can be 1 up to 12 or more. This spectrum can be used to calibrate the mass spectrometer and also provide internal lock masses for accurate mass measurement, described in applications below. 

Target compound analysis using high mass resolution, for example, for PCDD/ PCDFs, pesticides, POPs or pharmaceutical residues are typically performed by monitoring the compound-specific accurate mass ions at the expected retention time for each analyte. High resolution GC-MS target compound applications benefit from a unique technical feature referred to as the lock-mass technique for performing MID analyses. The lock mass technique provides ease of use, combined with a maximum quantitative precision and certainty in analyte confirmation. 

As a first step in this direction we will discuss here the two flavor color superconducting (2SC) quark matter phase which occurs at lower baryon densities than the color-flavor-locking (CFL) one, see [18, 32], Studies of three-flavor quark models have revealed a very rich phase structure (see [32] and references therein). However, for applications to compact stars the omission of the strange quark flavor within the class of nonlocal chiral quark models considered here may be justified by the fact that central chemical potentials in stable star configurations do barely reach the threshold value at which the mass gap for strange quarks breaks down and they appear in the system [20], Therefore we will not discuss here first applications to calculate compact star configurations with color superconducting quark matter phases that have employed non-dynamical quark models... 

For many applications, especially in the automotive industry, precision parts can only be mass-produced competitively and cost-effectively by using liquid silicone rubber. Successful applications include seals, 0-rings, membranes including central locking membranes, switch... 

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