Fast hydrophilic interaction liquid chromatographic separations on bonded zwitterionic stationary phase

Abstract

Separation science is an art of obtaining adequate resolution of the desired compounds in minimum time, and with minimum effort in terms of sample preparation and data evaluation. In LC, where selectivity is a main driving force for separation, the availability of different separation modes capable of operating at high flow rates is a way to make combined optimal use of selectivity, efficiency, and speed. The separation of polar and hydrophilic compounds is problematic in RP LC due to the poor retention. Hydrophilic interaction liquid chromatography (HILIC) is a more straightforward separation mode to address this problem. Herein, it is shown that separations in HILIC mode are equally efficient as for RP, providing a potential for very fast separations on short columns. This is not only facilitated by the low viscosity of the mobile phase compositions used, compared to typical RP eluents, but also due to higher column permeability. To exemplify this, baseline separations of uracil and cytosine are shown in less than 4 s and of Tamiflu and its main metabolite in less than 40 s, both under isocratic conditions. HILIC must therefore be considered having potential for high throughput purposes, and being an attractive candidate as the second separation dimension in 2-D HPLC.

Preparation and chromatographic evaluation of a cysteine-bonded zwitterionic hydrophilic interaction liquid chromatography stationary phase

“…And the A, B and C (Table 1) values were comparable with the coefficients in previous reports [36,37].…”

“…4, the stationary phase had minimum plate heights of 13-15 m in the linear velocity between 0.62 and 1.85 mm s −1 for cytosine, cytidine and orotic acid. The optimal flow rate of Click TE-Cys stationary phase was higher than the typical zwitterionic stationary phases [12,36]. And the plate heights were no more than 24 m within the tested flow rate 0.5-5.4 mm s −1 (0.3-3.5 mL min −1 ), demonstrating the high separation efficiency of Click TE-Cys stationary phase.…”

Metabolomics: Moving to the Clinic

“…However, the drawback of RP chromatography is that polar metabolites have poor retention and will thus elute in the void volume, making correct identification and quantification of these substances difficult. To address this, investigators have started to employ hydrophilic interaction chromatography (Tolstikov and Fiehn 2002;Appelblad et al 2008;Kamleh et al 2008;Kim et al 2009;T'Kindt et al 2008), which results in almost orthogonal retention order to RP (most polar metabolites elutes last). Multidimensional chromatographic setups using two or more LC separation phases for metabolic profiling are also described (Sabatine et al 2005;Lewis et al 2008).…”

Agglomerated silica monolithic column for hydrophilic interaction LC

“…However, the separation in Fig. 2 is slower than the 4 s separation of toluene, uracil and cytosine obtained on a 20 Â 2.1 mm ZIC-HILIC column (3.5 mm) [28]. The shorter length of the ZIC-HILIC column will have contributed to its greater speed.…”

“…Herein, we describe the performance of this latex-coated silica monolith under HILIC conditions. The HILIC performance is compared with the commercial Styros TM Amino polymeric HILIC monolith, ZIC s -HILIC column [28] and PolyWAX LP column [29] in terms of selectivity and efficiency.…”