Molecular composition hyphenated techniques

Hyphenation of chromatographic separation techniques (SFC, HPLC, SEC) with NMR spectroscopy as a universal detector is one of the most powerful and time-saving new methods for separation and structural elucidation of unknown compounds and molecular compositions of mixtures [171]. Most of the routinely used NMR flow-cells have detection volumes between 40... 

SEC-ESIMS is a valuable tool for polymer characterization. Compounds are separated based on their hydrodynamic size in solution, but upon detection, an absolute molecular weight is also furnished. Only 1% of the SEC effluent is required for ESIMS analysis, thereby accommodating the popular SEC detectors. SEC-ESIMS provides an attractive solution to the calibration of SEC without the use of external calibrants. Chemical composition distribution information on copolymers is easily afforded provided the individual monomers differ in molecular weight. The successively acquired mass spectra contain narrow fractions of the overall distribution that simplifies the analysis of complex formulations. Unfortunately, we have not been able to provide structured details on materials beyond 5000 Da due to the low resolution of the quadrupole mass spectrometer. Nevertheless, SEC-ESIMS is an exciting hyphenated techniques for polymer characterization. 

Schimpf ME (1995) Determination of molecular weight and composition in copolymers using thermal field-flow fractionation combined with viscometry. In Provder T, Barth HG, Urban MW (eds) Chromatographic characterization of polymers hyphenated and multidimensional techniques. American Chemical Society, Washington, DC, pp 183-196... 

This book covers some of the significant advances in hyphenated chromatographic separation methods for polymer characterization. Chromatographic separation techniques in this volume include size-exclusion chromatography, liquid chromatography, and field flow fractionation methods that are used in conjunction with information-rich detectors such as molecular size-sensitive or compositional-sensitive detectors or coupled in cross-fractionation modes. 

Jeon, S.J. Schimpf, M.E. Cross-fractionation of copolymers using SEC and thermal field-flow fractionation for determination of molecular weight and composition. In Chromatography of Polymers Hyphenated and Midtidimensiorud Techniques, Provder, T., Ed. ACS Symposium Series No. 731, Ch ter 10 ACS Publications Washington, DC, 1999 141-161. 

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