Detection Orthogonality in Macromolecular Separations: Role of the On-Line Viscometer in Characterizing Polymers at Conditions of “Spectroscopic Invisibility”

Striegel, André M.; Pitkänen, Leena

doi:10.1007/s10337-015-2898-7

Cited by 4 publications

(2 citation statements)

References 17 publications

(23 reference statements)

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“…All values were obtained by first-order fits of the data, without forcing through the origin. All Pearson’s r values were 0.997 or greater, except for polydimethylsiloxane (PDMS), for which the value was 0.798 due to the vanishingly low ∂ n /∂ c of PDMS at the given experimental conditions (so low, in fact, that PDMS can be considered to be “spectroscopically invisible” at these conditions [25]).…”

Section: Determining Mw By Off-line Batch-mode Malsmentioning

confidence: 99%

Specific Refractive Index Increment (∂n/∂c) of Polymers at 660 nm and 690 nm

Striegel

2017

Chromatographia

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The specific refractive index increment (∂n/∂c) is an essential datum for the accurate quantitation of molar mass averages and distributions (inter alia) of macromolecules when refractometry, static light scattering, and/or viscometry detection are coupled on-line to size-based separation techniques. The latter include methods such as size-exclusion and hydrodynamic chromatography, and asymmetric and hollow-fiber flow field-flow fractionation. The ∂n/∂c is also needed for accurate determination of the weight-average molar mass of polymers by off-line, batch-mode multi-angle static light scattering. However, not only does ∂n/∂c differ among chemical species, it also depends on experimental conditions such as solvent, temperature, and wavelength. For the last seventeen years, the author’s laboratories have measured the ∂n/∂c of a variety of natural and synthetic polymers, at both 690 nm and, more recently, 660 nm, under a variety of solvent and temperature conditions. In all cases, this has been done by off-line, batch-mode differential refractometry, not by assuming 100% analyte column recovery and 100% accurate peak integration. Results of these determinations are presented here, along with the relevant experimental data.

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Section: Determining Mw By Off-line Batch-mode Malsmentioning

confidence: 99%

Specific Refractive Index Increment (∂n/∂c) of Polymers at 660 nm and 690 nm

Striegel

2017

Chromatographia

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“…Continuing investigations into detector orthogonalities begun in [5], the same group more recently examined both detector and wavelength orthogonalities [6]. SEC with online refractometry (DRI), UV/visible (UV) where the UV was a diode array detector, and fluorescence (FL) detection, of polystyrene (PS) and poly(methyl methacrylate) blends demonstrated orthogonality of DRI and UV and, within the UV spectrum, wavelength orthogonality wherein one component of the blend was observable at one wavelength but not at another while the other blend component was observable at both wavelengths.…”

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confidence: 99%