HPLC–NMR of fatty alcohol ethoxylates

Abstract

The application of HPLC-NMR for the analysis of a mixture of fatty alcohol ethoxylates (FAEs) is described. The use of the new generation, cryogenically cooled probes is investigated in respect of the sensitivity advantage that they provide. The FAE mixture is separated using liquid chromatography at the critical point of adsorption. The ability of the method to differentiate between the different end groups and the degree of polymerization of the mixture constituents is investigated. Both on-flow and stop-flow HPLC-NMR techniques were used together with two-dimensional NMR spectroscopy. The results are compared with those obtained by using an evaporative light scattering detector for the HPLC.

Two‐dimensional chromatography of complex polymers, 8. Separation of fatty alcohol ethoxylates simultaneously by end group and chain length

“…5. Peak assignment has already been confirmed by previous LC‐NMR experiments 24. The order of elution confirms a retention mechanism based on hydrophobic interactions.…”

On-line coupling of high temperature GPC and 1H NMR for the analysis of polymers

“…Further studies on coupled HPLC-NMR have shown the power of liquid adsorption chromatography (LAC) for the analysis of polymers regarding the chemical composition [8][9][10][11][12][13]. It was shown that polyethylene oxides can be analysed with regard to functionality type distribution by identifying the different end groups [8].…”

“…It was shown that polyethylene oxides can be analysed with regard to functionality type distribution by identifying the different end groups [8]. In particular, liquid chromatography at the critical point of adsorption coupled to NMR allows the full assignment of the chemical structure and the degree of polymerisation of all oligomer species [10,11]. The critical point of adsorption was also used for the analysis of tacticity of poly(ethyl methacrylate)s by HPLC-NMR [12].…”

Multidimensional HPLC of Polymers

“…Krämer et al reported about SEC-NMR for the chemical composition analysis of poly(styrene-cobutyl acrylate) copolymers [152]. Further studies on coupled HPLC-NMR have shown the power of liquid adsorption chromatography (LAC) for the analysis of polymers regarding the chemical composition [153][154][155][156][157][158]. It was shown that polyethylene oxides can be analyzed with regard to functionality type distribution by identifying the different endgroups [153].…”

“…It was shown that polyethylene oxides can be analyzed with regard to functionality type distribution by identifying the different endgroups [153]. It has been shown that LCCC coupled to NMR allows for the full assignment of the chemical structure and the degree of polymerization of all 220 7 Hyphenation of Polymer Chromatography with Information-Rich Detectors oligomer species in complex mixtures [155,156]. sufficiently high flow rate, moderate sample concentration, and on-flow detection.…”