On the feasibility of Raman spectroscopy as a continuous off-line detection method for size- exclusion chromatography and related techniques

Published

July 1, 2015

Author(s)

Leena M. Pitkanen, Aaron A. Urbas, Andre Striegel

Abstract

Examined here is the feasibility of employing Raman spectroscopy as a detection method in size- exclusion chromatography (SEC) and related macromolecular separations, for the purposes of determining the chemical heterogeneity of copolymers. To this effect, heart-cutting fractions from the SEC peak of a gradient random copolymer of styrene (S) and methyl methacrylate (MMA) were collected, at concentrations resembling those of eluting slices in an analytical SEC experiment,and subsequently analyzed by off-line Raman. The amount (weight or mole percent) of styrene in each fraction was quantitated by Raman by applying a calibration curve constructed through the analysis of well-characterized block, alternating, and random S-MMA copolymers. The weight percent S (w% S) obtained from SEC with off-line Raman analysis of the gradient copolymer were compared to results previously obtained using SEC with on-line multi-angle static light scattering, differential refractometry, and ultraviolet absorption detection. Not only did Raman rank the w% S of the fractions in the correct order but, on average, Raman results differed by 3% or less as compared to the values obtained via multi-detector SEC. The results from this study demonstrate not only the feasibility of continuous off-line Raman detection for macromolecular separations but also the possibility of employing for this purpose the same or similar hardware to that currently used for continuous off-line Fourier transform infrared detection.

Citation

Polymer Chemistry

Pub Type

Journals

Download Paper

https://doi.org/10.1039/C5PY00189G

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Keywords

Size-exclusion chromatography, Raman spectroscopy, copolymers, chemical composition, molar mass

Citation

Pitkanen, L. , Urbas, A. and Striegel, A. (2015), On the feasibility of Raman spectroscopy as a continuous off-line detection method for size- exclusion chromatography and related techniques, Polymer Chemistry, [online], https://doi.org/10.1039/C5PY00189G, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917088 (Accessed April 19, 2024)