Molecular probe technique chromatography

The application of gas chromatography (GC) to the study of polymers has been hampered by their negligible volatility. A solution to this problem is the use of inverse gas chromatography (IOC, also called the molecular probe technique), which was developed by Sknids-red and Guillet (1) in 1969. The word "inverse" indicates that the component of interest is the stationary polymer phase, rather than the injected volatile substances. 

The static measurement is based on the addition of a water-swollen cellulose to a solution of the molecular probe. Water in pores accessible to the solute dilutes the solution. In the chromatographic techniques, either glass or standard liquid chromatography columns were packed with cellulose in various forms. The elution volumes of the molecular probes used were determined. Data is generally plotted as internal volume accessible to individual solutes against their molecular sizes. This is illustrated in Figure 5.43. 

Other in situ techniques have also been developed in recent years that measure changes in the chemical interactions that occur.150 They include inverse chromatography, in which the polymer is used as the stationary phase in a column or thin-layer mode, and a series of molecular probes is used to determine the molecular interaction capabilities of the polymer. These systems may be adopted to allow the application of electrical stimuli (as shown in Figure 1.27) to the polymer and to study... 

Molecular spectroscopy is a key method in almost all fields of ILs research. Starting with the assessment of the purity of ILs and study of their properties using different spectroscopic probes and their absorption and emission spectra, the reactions taking place in ILs are almost impossible to be studied without using molecular spectroscopy. Recording the UV-Vis or luminescence spectra is a commonly used technique for the detection of compounds by chromatography and electrophoresis, and ILs are more widely used in the respective studies. So, it is important to further investigate the applicability of ILs to molecular spectroscopy. 

The characterization of surface activity of fillers is obtained by use of several analytical techniques [1]. Examples of them are inverse gas chromatography [1, 2], the adsorption of a low molecular weight analog of elastomers [3], the adsorption of elastomer chains fi om dilute solutions [4], the wettability, viscosity of PDMS fluids in the boundary layer at the surface of solids [5], the determination of the specific surface area, and the analysis of surface groups [1]. It should, however, be mentioned that the results obtained by these methods do not provide direct information on the elastomer behavior at the interface, due to the use of small probe molecules or the presence of a solvent in the systems studied. 

A second analytical measurement of protein purity, which should be conducted, is HPLC analysis. Various chromatography columns can be utilized to verify the purity of the protein. The most commonly employed methods are ion exchange chromatography, molecular sieve chromatography (also known as gel permeation chromatography), and hydrophobic interaction chromatography (HlC). Each of these techniques probe a different chemical aspect of the protein and provide excellent independent check of purity and homogeneity. 

When faced with the MS analysis of a moderately labile sample, derivatization followed by conventional MS (El or Cl) often proved to be more practical than the specialized MS techniques. The relatively low cost and subsequent availability of this approach served to bolster the development of sensitive derivatization techniques for use in probe and gas chromatography-mass spectrometry (GC-MS) experiments. The gains in volatility and thermal stability available through derivatization substantially extended the applicability of mass spectrometry. However, as sample molecular weight and thermal instability increased, derivatization was no longer able to provide the increased p>erformance observed at low mass (< 1500 daltons). This problem was further compounded by the net increase in sample molecular weight associated with most derivatization procedures. 

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