Ionic matrices

Carda-Broch, S., Berthod, A. and Armstrong, D. W., Ionic matrices for matrix-assisted laser desorption/ionization time-of-flight detection of DNA oligomers. Rapid Commun. Mass Spec., 17, 553, 2003. 

Figure 1. Excess internal energy (split in ion-dipole (fluio = flU o/V) and dipole-dipole (3un = SU fl/V) contributions) and chemical potential for a dipolar fluid inclusion in ionic matrices quenched at low temperature floe2/a — 1 (solid line and filled triangles) and high temperature floe2/a = 0.005 (dashed line and filled circles). The dotted lines correspond to the ion-dipole equilibrated mixture at fle2 /a = 1 for the corresponding charge densities. Curves denote ROZ results and symbols GCMC data[18].

Pukhov KK, Pelle F, Heber J (2003) Multiphonon relaxation of excited rare-earth ions in ionic matrices. Mol Phys 101 1001-1006... 

A series of ILs, including AILs and PILs, were trialed as ionic matrices for use with matrix-assisted laser desorption/ ionization mass spectrometry (MALDI-MS). The ILs were of irrterest beeause of their high solubilizing power, negligible vapor pressure, artd broad liquid terrrperatures. 

For completeness sake, there also exists a form of sputtering known as potential sputtering. This describes sputtering as occurring through purely inelastic processes, i.e. without the requirement of momentum transfer. As extensive energy transfer is involved, these typically result in atomic emissions alone. These are rare and tend only to occur on specific highly ionic matrices. 

It has been demonstrated that ionic liquids and solids make useful MALDI matrices. With ionic matrices, it is possible to combine the beneficial qualities of liquid and solid matrices. Ionic liquids produce a much more homogeneous sample... 

Thirty-eight different ionic matrices having excellent solubilizing properties and vacuum stability were synthesized and tested with peptides, proteins, and poly(ethylene glycol) (PEG-2000) analytes. Out of 38 ionic matrices tested, 20 ionic matrices produced homogeneous solutions of greater vacuum stability, higher ion peak intensity, and equivalent or lower detection limits than conventional solid matrices. 

Lemaire R,Tabet J, Ducoroy P, et al. Solid ionic matrixes for direct tissue analysis and MALDI imaging. Anal. Chem. 2006 78 809-819. 

LC separation applying ion chromatography in combination with ion spray mass spectrometric detection was applied for the examination of a synthetic mixture of alkyl sulfonates (CnH2n+i-SO3 re = 8) and AS with different alkyl chain lengths in the selected ion monitoring (SIM) ESI-MS(—) mode [53], Selected ion current profiles provided the separation of the compounds. The ionic matrix constituents of the eluent were removed by a suppressor module prior to MS detection to improve the signal to noise (S/N) ratio. 

Further evidence for microphase separahon has been seen by AFM. As expected, BPSH 00, with no ionic regions, displays no significant features in its AFM image. For BPSH 20, isolated ionic clusters have dimensions of 10-25 nm. These clusters are even more readily discerned from the non-ionic matrix in BPSH 40, but the domains appear to remain relatively segregated from each other. In the case of BPSH 50 and 60, connections between domains are clearly visible, especially in the case of the latter sample. It also should be noted, however, that these samples were in a dehydrated state. Therefore, it might be expected that even in the case of the lower acid content samples, it is likely that some channel formation between ionic domains will still occur upon the uptake of water. This can be clearly seen in its linear conductivity behavior as a function of disulfonated monomer (i.e., the percolation threshold has been reached by at least 20-30% content of disulfonated monomer). 

Meriaux C, Franck J, Wisztorski M, Salzet M, Fournier I (2010) Liquid ionic matrixes for MALDI mass spectrometry imaging of lipids. J Proteomics 73 1204-1218. doi 10.1016/j. jprot.2010.02.010... 

Liu Q, He L (2009) Ionic matrix for matrix-enhanced surface-assisted laser desorption/ionization mass spectrometry (ME-SALDI-MS). J Am Soc Mass Spectrom 20 2229-2237. doi 10.1016/j.jasms.2009.08.Oil... 

An area in which functionalised ionic liquids are already playing an important role in catalysis is heterogenisation on solid supports. The general concept involves the immobilisation of imidazolium and other cationic fragments onto solid supports using appropriate functional groups attached to the cation. An ionic catalyst then resides within the ionic matrix and several examples of such supported ionic liquid phase catalysts are provided in the subsequent chapters of this book. The concept is illustrated in Figure... 

The extension of the ROZ formalism to confined molecular fluids has recently been carried out for adsorbed diatomic molecules [6] and dipolar fluids confined in hard sphere matrices [18, 19], In the case of ionic matrix, new features of the system have to be taken into account. On one hand, we have now a two component matrix (with positive and negative ions). This case was already considered in [14, 15] for the primitive model electrolyte adsorbed in an electroneutral charged matrix. On the other hand, we have to deal with two different temperatures the matrix temperature, (h (at which the ionic fluid is equilibrated before quenched) and the fluid temperature fi, at which the fluid is adsorbed in the solid matrix. As usual when dealing with molecular fluids one starts with an expansion of the correlation functions in terms of spherical harmonics as follows,... 

We also compare in both figures the dielectric constant values of the dipolar fluid when adsorbed in the ionic and in the hard sphere matrix. A clear influence of the presence of charges in the matrix is then observed. The ionic matrix lowers the response of the dipoles to an external field, i.e. lowers the value of the dielectric constant of the fluid in the given state. This can easily be understood, since the local electric field that the matrix charges generate... 

In most applications, the method of cation exchange with direct conductivity detection does not have the required specificity for the analysis of heavy and transition metals. Ionic matrix components which are often present in high excess are also detected. 

Penicillin G acylase (PGA) has pivotal role in industry for the synthesis of penicillin antibiotics. PGA catalyzes the hydrolysis of peniciUm and other P-lactam antibiotics to produce 6-amino penicillinic acid [53, 54]. Stability of PGA was investigated by assaying the enzyme activity at different time points after incubation of PGA in various ILs [53]. In the absence of substrate, about 2,000-fold increase in t, was observed in a hydrophobic IL, [EMIM][Tf2N] with respect to twpropanol. Whereas in the presence of substrate, PGA showed less stability in [Tf N]" containing ILs. The reverse trend was found for PGA in a water miscible IL [BMIM][PFg], i.e., PGA showed 9 times increase in tj in [BMIM][PF ] in the presence of substrate even at an elevated temperature of 40°C [54]. These altered t, values in hydrophobic ILs in the presence of substrates were explained on the basis of cumulative outcome of specific interaction of substrates with the active site of enzyme and inhibitory effect of the hydrolytic products formed in the reaction medium. It can be speculated that in a more hydrophilic IL like [BMIM][PF ], substrates shield the enzyme active site from direct interaction with the ionic matrix and thus imparts a stabilizing effect whereas in hydrophobic IL [EMIM][TfjN], the inhibitory effect of hydrolytic products predominates and destabilizes the enzyme. 

Liquid ionic matrixes for MALDI mass spectrometric imaging of lipids. /. Proteomics, 73, 1204-1218. 

The same MALDI-based assay approach with DHB butylamine (DHBB) was implemented to monitor the desialylation reaction of 3 -sialyUactose [128]. DHBB is a liquid ionic matrix prepared by mixing equimolar amounts of DHB and butylamine, and can be used in lieu of an organic solvent in the enzyme reaction, thereby allowing rapid monitoring of the enzyme-catalyzed reaction. 

The treatment of the samples from environmental matrices is an important issue in CE. Little attention has been given for the water sample treatment in CE analysis of environmental pollutants. Soil samples have been extracted by the usual methods. Besides, the sediment samples were digested using strong acids. The samples containing a highly ionic matrix may cause problems in CE. EOF in the capillary can be altered by the influence of the sample matrix, resulting in poor resolution. Additionally, the... 

Liu Q, Zhang P, Qing A, Lan Y, Lu M (2006) Poly(N-isopropylacrylamide) hydrogels with improved shrinking kinetics by RAFT polymerization. Polymer 47 2330 Magnin D, Lefebvre J, Chomet E, Dumitriu S (2004) Physicochemical and structural characterization of a poly ionic matrix of interest in biotechnology, in the pharmaceutical and biomedical fields. Carbohydr Polym 55 437... 

Ion-exchange methods are based essentially on a reversible exchange of ions between an external liquid phase and an ionic solid phase. The solid phase consists of a polymeric matrix, insoluble, but permeable, which contains fixed charge groups and mobile counter ions of opposite charge. These counter ions can be exchanged for other ions in the external liquid phase. Enrichment of one or several of the components is obtained if selective exchange forces are operative. The method is limited to substances at least partially in ionized form. 

Another approach to matrix matching, which does not rely on knowing the exact composition of the sample s matrix, is to add a high concentration of inert electrolyte to all samples and standards. If the concentration of added electrolyte is sufficient, any difference between the sample s matrix and that of the standards becomes trivial, and the activity coefficient remains essentially constant. The solution of inert electrolyte added to the sample and standards is called a total ionic strength adjustment buffer (TISAB). 

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