Potential and limitations of on-line comprehensive reversed phase liquid chromatography×supercritical fluid chromatography for the separation of neutral compounds: An approach to separate an aqueous extract of bio-oil

Abstract

On-line comprehensive Reversed Phase Liquid Chromatography×Supercritical Fluid Chromatography (RPLCxSFC) was investigated for the separation of complex samples of neutral compounds. The presented approach aimed at overcoming the constraints involved by such a coupling. The search for suitable conditions (stationary phases, injection solvent, injection volume, design of interface) are discussed with a view of ensuring a good transfer of the compounds between both dimensions, thereby allowing high effective peak capacity in the second dimension. Instrumental aspects that are of prime importance in on-line 2D separations, were also tackled (dwell volume, extra column volume and detection). After extensive preliminary studies, an on-line RPLCxSFC separation of a bio-oil aqueous extract was carried out and compared to an on-line RPLCxRPLC separation of the same sample in terms of orthogonality, peak capacity and sensitivity. Both separations were achieved in 100min. For this sample and in these optimized conditions, it is shown that RPLCxSFC (with Hypercarb and Acquity BEH-2EP as stationary phases in first and second dimension respectively) can generate a slightly higher peak capacity than RPLCxRPLC (with Hypercarb and Acquity CSH phenyl-hexyl as stationary phases in first and second dimension respectively) (620 vs 560). Such a result is essentially due to the high degree of orthogonality between RPLC and SFC which may balance for lesser peak efficiency obtained with SFC as second dimension. Finally, even though current limitations in SFC instrumentation (i.e. large extra-column volume, large dwell volume, no ultra-high pressure) can be critical at the moment for on-line 2D-separations, RPLCxSFC appears to be a promising alternative to RPLCxRPLC for the separation of complex samples of neutral compounds.

Optimizing separations in online comprehensive two‐dimensional liquid chromatography

“…Because SFC allows fast separations, it is potentially most attractive as 2 D technique. Sarrut et al [162] described RPLC × SFC for complex mixtures of neutral compounds. SFC is also potentially interesting as 1 D technique, because the mobile phase is compatible with 2 D RPLC, as demonstrated by François et al [163,164].…”

Measuring biomass fast pyrolysis kinetics: State of the art

“…In addition, mechanistic studies describe the type of reaction intermediates and competing pathways involved in the product formation (Asatryan, Bennadji, Bozzelli, Ruckenstein, & Khachatryan, 2017;Bahrle, Custodis, Jeschke, van Bokhoven, & Vogel, 2014;Custodis et al, 2014;Furutani, Dohara, Kudo, Hayashi, & Norinaga, 2018;Khachatryan et al, 2016;Kibet, Khachatryan, & Dellinger, 2012;Kim, Bai, Cady, Gable, & Brown, 2015;Koirala, Villano, Carstensen, & Dean, 2013;Qi, Zhang, Kudo, Norinaga, & Hayashi, 2017;Seshadri & Westmoreland, 2012;Shen, Jarboe, et al, 2015;Wornat, Ledesma, & Marsh, 2001;Xu, Khachatryan, Baev, & Asatryan, 2016). Advances in analytical techniques have made it possible to even detect intermediate radicals and important product species (Bahng et al, 2009;Kanaujia, Sharma, Agrawal, & Garg, 2013;Michailof, Kalogiannis, Sfetsas, Patiaka, & Lappas, 2016;Negahdar et al, 2016;Pouwels, Eijkel, & Boon, 1989;Sarrut et al, 2015;Traore, Kaal, & Martinez Cortizas, 2016). Results obtained with such techniques play a crucial role in the evolution of detailed biomass fast pyrolysis reaction mechanisms.…”

Development of a supercritical fluid chromatography method with ultraviolet and mass spectrometry detection for the characterization of biomass fast pyrolysis bio oils

“…In case of very complex samples, it can be assumed that the least retained compound is eluted in the void volume (k 1,iso =0) while the last eluted peak in the initial isocratic step is eluted at the beginning of the gradient which means that φ 1,grad corresponds to the initial composition φ ini and that From Eqs. (2), (3), (8) and (9), the resulting equation for the total sample peak capacity can be expressed as It was first necessary to verify that Eq. 7was valid, namely that LSST could be applied to linear gradients in SFC as can be done in RPLC (reversed phase liquid chromatography).…”