SinS - Abstract

Abstract Information :

Temperature responsive liquid chromatography offers a number of unique benefits in liquid chromatography allowing overcoming some long-lasting detection and separation issues in HPLC and LCxLC. This separation mode which is based on stimuli-responsive polymers anchored to the supporting material packed in HPLC columns, allows for promising control of the solutes retention as a function of temperature within moderate temperature ranges (e.g. 5-50°C), whereby the necessity of solvent gradients can be overcome. Most responsive polymers studied and exploited so far in HPLC depict a change in polarity and hence in chromatographic retention with temperature in 100% aqueous mobilize phases. In LCxLC this purely aqueous nature of the TRLC mobile phase allows for effective refocusing of organic solutes prior to the second-dimension RP separation using a conventional 10-port valve interface. The latter is beneficial as it makes simplification of LCxRPLC method development possible and therefore allows for robust interfacing. Additionally, the refocusing allows for miniaturization of the second dimension I.D. (2D) as compared to the first dimension (1D). This inverts the dilution issue in LCxLC into a re-concentration solution and allows for more sensitive detection as compared to U(H)PLC when concentration sensitive detectors are used. The TRLCxLC approach also offers enhanced control of sensitivity in other ways e.g. through the implementation of flow gradients TRLC in combination with conventional RPLC, increasing the signal to noise ratios. While various benefits are reachable by TRLCxRPLC also in 1D-TRLC detectors and quantitative methods can benefit from the isocratic nature of this separation. This is e.g. illustrated through the combination of (temperature gradient controlled) TRLC with refractive index detection, broadening the applicability range of this detector in quantitative analysis. While most TRLC work has thus far been performed under purely aqueous conditions, the latter is not obligatory and certain fractions of organic modifiers can be tolerated while preserving the responsive effects. The latter is illustrated for various organic co-solvents, paving the way also for the use of aqueous (green) organic solvent mixtures, whereby a range of responsive polymers can be envisaged. The above aspects are shown for a variety of synthesized temperature responsive polymer based packed columns. References: [1] Baert, M; Martens, C; Desmet, G; de Villiers, A; Du Prez, F; Lynen, F. Analytical Chemistry, 2018, 90, 8, 4961-4967. [2] Wicht, K; Baert, M; Kajtazi, A; Schipperges, S; von Doehren, N; Desmet, G; de Villiers, A; Lynen, F. Pharmaceutical impurity analysis by comprehensive two-dimensional temperature responsive x reversed phase liquid chromatography. Journal of Chromatography A, 2020, 1630, 461561 [3] Wicht, K; Baert, M; Muller, M; Bandini, E; Schipperges, S; von Doehren, N; Desmet, G; de Villiers, A; Lynen, F. Comprehensive two-dimensional temperature-responsive x reversed phase liquid chromatography for the analysis of wine phenolics. Talanta, 2022, 122889 [4] Ampe, A; Wicht, K; Baert, M; Broeckhoven, K; Lynen, F. Investigation of the potential of mixed solvent mobile phases in temperature-responsive liquid chromatography (TRLC). Analyst, 2021, 146, 6990-6996. [5] Baert, M; Wicht, K; Hou, ZH; Szucs, R; Du Prez, F; Lynen, F. Exploration of the Selectivity and Retention Behavior of Alternative Polyacrylamides in Temperature Responsive Liquid Chromatography. Analytical Chemistry, 2020, 92, 9815-9822.