Ion capacity

What is one of the significant advantages of a linear (2D) ion trap mass analyzer when compared to a 3D (Paul) ion trap (increased ion capacity, which leads to improved sensitivity). 

Figure 2.33 represents such a linear trap. The two detectors allow the use of all the ions expelled from the trap. Trapping efficiency is in the range 55-70 % while it is only 5 % in the Paul ion trap. Unit resolution is achieved at 16 700 Th s 1 scan rate. At 27 Th s 1, Am = 0.05 is observed at m/z 1520, corresponding to a resolution of 30000 FWHM. The ion capacity is about 20 000, 40 times more than in the Paul ion trap. 

Hard carbons were synthesized by carbonizing various combinations of phenolic resin precursors in order to obtain a material with a structure suitable to be used as the anode material in lithium ion battery systems, i.e. a carbon with a large pore volume and small pore openings. The lithium ion capacities of thus obtained carbons were also measured. From the obtained results, strategies to obtain hard carbons with large reversible capacities and small irreversible capacities are proposed. 

This is a complicated function of the small ion capacity (usually 1 to 10 mequiv/g) and the physical properties of the resin (because the ion-exchange groups must be readily accessible to the polyelectrolytes under the conditions of the chromatography). Also important is the rate at which equilibration occurs. 

Ion capacity of several polybenzylamine and ethylene-imine polymers... 

The maximal binding capacity was determined at certain pH values, using both batch and column methods. In the batch methods, the total amount of the metal salt was always in 2-3 fold excess over the theoretical ion capacity, and the metal uptake by the polymers was calculated from the dif-ference.s in metal concentration prior and after the equilibration. In the column method. 500 1000 ml of 0.1- 0.5 M metal sulphate solution was passed through a 10 50 g polymer in a column at a rate of 1 ml/min. Tractions were collected until the initial ion concentration was achieved. The metal uptake was calculated again from the total amount of metal ions recovered in solution, by difference. 

Although 3D traps have been extensively used, during the early to mid-2000s, for structural elucidation of metabolites, overall a slower scan rate compared to TOF mass analyzers, in combination with limited ion capacity and trapping efficiency are the limitations associated with the QITs for becoming the mass analyzer of choice for quantitative/qualitative bioanalysis. Most importantly, 3D traps can only simulate SRM by acquiring full-scan MS data, true SRM scan modes can only be... 

A typical cation-exchange resin of the sulfonated styrene-divinylbenzene (DVB) type, such as Dowex 50, has an exchangeable ion capacity of 5.0 meq/g of dry resin. As shipped, the water-wet resin might contain 41.4 wt% water. Thus, the wet capacity is 2.9 meq/g of wet resin. If the bulk density of a drained bed of wet resin is 0.83 g/cm3, the bed capacity is 2.4 eq/L of resin bed (Seader and Henley, 2006). 

Adsorbent Base matrix/surface modification dp (pm) > Mean pore radius (nm) Ion capacity (pmol mr ) Dynamic capacity (BSA mg ml )... 

An important configuration of quadrupoles is the triple quadrupole (QqQ), in which there are two analytical quadrupoles (Q) separated by a transmission quadrupole (q). While the predominant use of the QqQ is in quantification, this very versatile format has several scanning modes that enable multiple MS/MS approaches to obtain structural information (Section 3.3.3.1). Extensions of the quadrupole technology are the quadrupole ion trap (QIT) and the more recent linear ion trap (LIT) that has higher ion capacity. The resolutions of these ion traps are similar to those of single quadrupoles. However, an advantage of the traps is the ability to store and manipulate ions prior to their detection, thus enabling MS/MS experiments (Section 2.3.2). 

The introduction of nitrile groups into proton conductive sulfonated thermoplastics decreases their moisture absorption [9]. Nitriles promote the adhesion of the polymers to heteropolyacids (HPA)s in composite membranes or to electrodes. In addition, the dimensional stability of the membrane is improved. Thus, PEN membranes with higher ion capacity should be possible, operating at lower humidities [40]. 

Anrcjl) are the occupied volumes of the same instruments, respectively. For collisionally focused ion clouds at a common rf potential and radial frequency, rA = = fc = 1.0 mm based on ion tomography experiments, the ratio Nzd,a N2D,b N3d = 95 22 1. This ratio suggests an ion capacity for the linear ion trap two orders of magnitude greater than that of the 3D ion trap. 

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