Thermal Field-Flow Fractionation Universal Calibration: Extension for Consideration of Variation of Cold Wall Temperature

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• 作者：Wenjie Cao ; P. Stephen Williams ; Marcus N. Myers ; and J. Calvin Giddings
• 刊名：Analytical Chemistry
• 出版年：1999
• 出版时间：April 15, 1999
• 年：1999
• 卷：71
• 期：8
• 页码：1597 - 1609
• 全文大小：136K
• 年卷期：v.71,no.8(April 15, 1999)
• ISSN：1520-6882

文摘

The well-known size exclusion chromatography (SEC)universal calibration allows the characterization of apolymer sample using a set of polymer standards of adifferent polymer family. This is a polymer-transferablecalibration method. A more "universal" calibration methodhas been proposed for thermal field-flow fractionation(ThFFF) where the calibration constants closely describethe ratio of ordinary (molecular) diffusion coefficient Dto thermal diffusion coefficient (or, more correctly, thermophoretic mobility) D_T. The universal calibration forThFFF is therefore instrument or system transferable.Systematic experiments have previously been carried outto verify this calibration method for a wide range ofconditions. Results showed that the method holds wellprovided experimental conditions such as sample size andcold wall temperature T_c are the same for each system.This paper quantifies the effect of cold wall temperatureon polymer retention in ThFFF and on the universalcalibration constants for the polystyrene-tetrahydrofuran,poly(methyl methacrylate)-tetrahydrofuran, and polyisoprene-tetrahydrofuran systems, respectively. The universal calibration for ThFFF is thereby extended toaccount for variation of cold wall temperature. The extended calibration will allow for accurate data retrievalfrom analyses obtained at any cold wall temperature. Itwill even allow for accurate information retrieval whencold wall temperature is not held constant during sampleelution, such as may occur with a change in coolant flowrate or with a programmed decay of T.