Ion-Pair Chromatography IPC

Another form of ion chromatography is ligand exchange chromatography where a cation exchange resin is used to separate analytes that can form coordination complexes with the metal attached to the resin. 

Ion-exchange chromatography involves more variables than other forms of chromatography. Distribution coefficients and selectivities are functions of pH, solute charge and radius, resin porosity, ionic strength and type of buffer, type of solvent and temperature. The number of experimental variables makes lEC a very versatile technique but a difficult one because of the effort needed to optimise a separation. 

One recent application in lEC consists of solid phase extraction disks which are used to eliminate matrix interference prior to analysis. The disk contains a membrane composed of resin beads enmeshed in a PTFE membrane, housed in a polypropylene housing. The resin is treated to remove specific ions such as H+ to remove hydroxide, Ag+ for excess halides and Ba to remove sulphate. Other disks such as hydroxide for acid removal and neutral styrene-divinylbenzene to eliminate hydrophobic components which can damage resin based IC columns are being developed [23]. 

A summary of the appHcations of ion chromatography in the analysis of foods can be found in one of the Journal of Chromatography Library [24]. The same volume also describes in great detail the principles of ion chromatography. 

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Ion-pair chromatography (IPC) is a further example of the use of secondary chemical equilibria to control retention and... 

Table 3.10f lists the most relevant parameters for ion-pairing chromatography (IPC). Here there are four major primary parameters, which cannot be seen as independent. Hence (see section 5.1.1), these four parameters should preferably be optimized simultaneously. Sensible upper and lower limits may be set for each of the parameters and an optimized separation may result from the process. If this is not the case, there arestill many secondary parameters that could be exploited. 

Ion Pair Chromatography (IPC). This discussion is limited to the most common type of IPC—reverse phase mode using bonded alkyl ligates (like C)8 and Cg) as the stationary phase. Its main advantage over regular reverse phase LC is that it facilitates the analysis of samples that contain both ions and molecular species. 

The development of most ion-pairing chromatography (IPC) methods started with optimization of the mobile phase composition after an appropriate column was selected. The theory described in Chapter 3 assists the chromatographer to perform educated guesses. Chapters 7 through 10 discuss the main qualitative and quantitative attributes of tunable mobile phase parameters to illustrate their influence on the global performance of the method. 

Helfrich, A. and Bettmer, J. Determination of phytic acid and its degradation products hy ion-pair chromatography (IPC) coupled to inductively coupled plasma-sector field-mass spectrometry (ICP-SF-MS). /. Anal. Atom. Spectrom. 2004, 19, 1330-1334. 

Ion-pair chromatography (IPC) is more susceptible to peak fronting than other modes in LC. Column temperature problems can cause fronting peaks in IPC. Figure 1 shows the separation of an antibiotic amine at ambient temperature. Repeating the... 

Ion pair chromatography (IPC) using a mobile phase containing an opposite charged ion compared to the analyte... 

The mobile phase used in HPLC is dependent on the hydrophobicity of the compounds. Appropriate mixtures of methanol (or an appropriate organic solvent such as acetonitrile) and water (or buffer solution), with or without ion pair chromatography (IPC) reagents, are used. 

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