High-temperature size exclusion chromatography

The effect of temperature on column efficiency, however, is frequently exploited, particularly in size exclusion chromatography (SEC). As has already been discussed, high efficiencies are essential in SEC due to the limited peak capacity of the column and consequently, the very small separation ratios. However the effect of temperature on column efficiency is not well understood by many analysts and consequently, will be discussed in some detail. It was shown on page... 

As mentioned above, two experimental methods were examined as a source of kinetic samples Method A Agitated Glass Ampoule and Method B Static Mixer. These are described in turn in the following paragraphs. Analysis of samples was done using high temperature size exclusion chromatography (SEC) under conditions previously described (9.101. 

Haddon, M. R. and Hay, J. N., High-temperature size exclusion chromatography, in Size Exclusion Chromatography, Hunt, B. J. and Holding, S. R., Eds., Blackie, Glasgow, 1989, chap. 4. 

Watson and Kenney [62] describe the use of high-performance size-exclusion chromatography to examine the aggregation of interferon-y and interleukin-2 after storage at elevated temperature, after mechanical agitation, and following rapid freeze-thaw. An excellent review on SEC can be found in Ref. 63. 

A viscosity online detector in a size exclusion chromatography (SEC) instrument allows for a universal calibration for polymers with known K- and a-values. For polymers that are only soluble at high temperature, e.g., polyolefines, high-temperature detectors are available, which can be operated up to 200°C. In addition to molar mass measurements, viscosity detectors have also been employed successfully to obtain structural information of branched polymers [28]. 

High-Temperature Size Exclusion Chromatography of Polyethylene... 

Brus et al. prepared isolated silicon particles by high temperature pyrolysis of disilane with a subsequent passivation of the surface by oxidation [33]. The particles of various size are then processed by high-pressure, liquid-phase, size exclusion chromatography to separate sizes and obtain various fractions of monosize particles. Such particles represent an almost ideal model of silicon quantum dots. 

Profile The company was founded in 1976 to develop techniques and instrumentation for the characterization of polymer systems, and to develop high-technology polymer products for chromatography, and for diagnostic and pharmaceutical applications. The company operates from offices in the USA, UK, and Europe. Primary products are in the specialized areas for gel permeation/size exclusion chromatography (GPC/SEC) including columns, standards, advanced high temperature systems and detectors, and GPC/SEC software. 

Most separations in liquid chromatography are performed at room temperature for convenience and because ambient temperatures provide reasonable column efficiency for low molecular mass solutes. Elevated temperatures are commonly used in ion-exchange chromatography to improve mass transfer kinetics and in size-exclusion chromatography to provide adequate solubility for polymers in useful mobile phases. Wider interest in temperature control and high-temperature separations in general results from improved precision of retention measurements (section 1.1.1), greater column efficiency (section 1.5.2), the use of temperature as a variable for method development (section 4.4.4), and shorter separation times due to the more favorable use of the column inlet pressure [70,71]. 

---