Adsorption-Partition Switching of Retention Mechanism in Ice Chromatography with NaCl-doped Water-Ice

Abstract

Adsorption and partition are the most fundamental phenomena involved in various natural and industrial processes, and, in analytical chemistry, have been utilized for various purposes: e.g. separation, condensation, removal of interferents etc. [1][2][3][4][5][6][7] Silica gel, alumina, activated carbon, and synthetic or natural polymers have found various applications as adsorbents. [1][2][3][4] On the other hand, partition has also long been studied as an essential mechanism in solvent extraction. [5][6][7] Although earlier work of solvent extraction focused on the bulk processes occurring in liquid phases, current methodologies have revealed the important involvements of interfaces in partition phenomena; 8 e.g. interfacial processes determine the kinetics of the entire partition reactions in some cases. However, as far as most of the molecular interactions in condensed phases are concerned, adsorption dominantly occurs on the surface of a solid whereas partition mostly occurs in a liquid phase.The terminology of adsorption and partition is often used for the classification of chromatography, i.e. adsorption chromatography and partition chromatography. 9 Liquid chromatography with silica gel as a stationary phase is a typical example of adsorption chromatography, while reversed-phase chromatography with ODS silica gel is usually considered as partition chromatography. In the latter mode, the retention mechanism is explained on the basis of the assumption that the hydrocarbon layer on the stationary phase surface accommodates a solute in a way similar to the solvation in a bulk solvent. Thus, adsorption and partition mechanisms are clearly distinguished from each other in usual liquid chromatography. Some studies have indicated that the surfaces of an ODS stationary phase show solid-liquid phase transition at a particular temperature; it was detected e.g. by a flection point of a van't Hoff plot. 10 If this consideration were correct, the retention mechanism would also be altered at the phase transition temperature between adsorption and partition. However, such a change actually depends on various factors and occurs over a relatively broad temperature range rather than at a well-defined phase transition temperature. Thus, this is not a real phase transition.The temperature is an important factor affecting chromatographic retention even though the retention relies on a single mechanism. However, if a phase transition occurs, a drastic change in retention is expected. Kanazawa et al. 11 have published a number of papers concerning temperatureresponsive stationary phases. They have utilized polymers showing a temperature-induced change in hydration. An aqueous solution of this polymer gives a well-defined critical temperature, at which its aqueous solution becomes turbid when warmed. This phase transition allows the modification of the hydrophobicity of the stationary phase surface simply by heating a separation column slightly higher than the ambient temperature.We have proposed ice chromatography, in which wa...

A review of air–ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow

“…This was corroborated by the work of Domine et al (2001), who used infrared spectroscopy to show that the high concentrations used considerably perturb the ice structure, rendering it almost amorphous, so that the diffusion coefficients measured are not those of crystalline ice. Indeed, Livingston et al (2000) report D HCl = 5 × 10 −14 m 2 s −1 at 170 K, an unrealistically high value, compared to values in the range 10 −16 to 10 −15 m 2 s −1 at 238-265 K found by Thibert and Domine (1997). The profiling techniques discussed above are destructive, rendering direct in situ observation of the diffusion process difficult.…”

“…Grain boundaries, the contact area between two ice crystals, and other defects in the ice such as dislocations and small-angle boundaries, which are formed by a 2-D network of regrouped dislocations, can act as diffusion short-circuits (Domine et al, 1994;Thibert and Domine, 1997;Barret et al, 2011a). Similarly, the triple junctions (so-called veins) and quadruple points (nodes) between ice crystals are candidates for such diffusion short cuts.…”

“…Other early studies of SO 2 uptake on ice doped with NaCl also found that the observed partitioning can be well described by dissolution into a liquid phase if its volume is estimated using melting point depression . Similarly, Tasaki and Okada (2009) examined the retention of water-soluble organics in a chromatographic column packed with ice spheres. The ice was doped with NaCl and it was found that the retention largely increased with the formation of liquid brine.…”

Design of Analytical Systems Based on Functionality of Doped Ice

“…Mixed adsorption-partition ice chromatography was examined with hydroquinone (HQ) and resorcinol (RS) as test solutes. 14,15 The retention of RS on the pure ice stationary phase is larger than that of HQ, possibly because of the steric preference for RS in the adsorption process on the ice surface. In contrast, the partition of HQ into an aqueous phase is larger than that of RS.…”

Shear-Driven Flow Ice Chromatography as a Possible Tool Probing Ice/Water Interface

“…Ice chromatography, in which ice particles are used as a liquid chromatographic stationary phase, has been used for separation based on adsorption through hydrogen bonding between solutes and the ice surface, [1][2][3] retention control by adsorption/partition switching, 4,5 and chiral separation. 6,7 This method also provides information on phenomena occurring at the interface between the ice and a mobile phase.…”