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Rheinmünster, Germany

Pursch M.,Analytical Technology Center | Buckenmaier S.,Hewlett - Packard
Analytical Chemistry | Year: 2015

Loop-based multiple heart-cutting (MHC) two-dimensional liquid chromatography (2D-LC) is presented as a solution to quantify target components in complex matrices, such as additives in polymers, at very high chromatographic resolution. The determination of hexabromocyclododecane (HBCD) in polystyrene (PS) is described. One dimensional (1D) LC analysis with UV detection did not allow quantitation of the main isomers of HBCD due to peak overlap with polymer components. MHC 2D-LC analysis provided the separation power, accuracy, and repeatability needed for quantitative analysis of the additives of interest. Heart-cuts from peaks of the 1D-chromatogram or entire regions of interest are sampled into loops, where they remain parked until their sequential reinjection onto the second dimension (2D) column. A column set consisting of phenyl (1D) and C18 (2D) stationary phases gave baseline separation in 2D between HBCD and PS background. Linearity for spiked polymer samples was achieved over a range of 0.02-1.00 wt % HBCD relative to the amount of polymer. The limit of quantitation was estimated at 0.01 wt % HBCD in PS. A peak area RSD of 0.7% obtained for ten replicates of a real sample demonstrated excellent repeatability of the analysis. MHC 2D-LC is an elegant solution for quantitative analyses of difficult-to-separate samples when conventional 1D separation fails. © 2015 American Chemical Society.

Pursch M.,Analytical Technology Center | Eckerle P.,Analytical Technology Center | Gu B.,Dow Chemical Company | Luong J.,Fort Technologies | And 2 more authors.
Journal of Separation Science | Year: 2013

Low thermal mass LCwas applied to the capillary LC separation of a complex insecticide mixture by increasing temperature and decreasing gradients, as well as fast selected temperature pulses to increase resolution of overlapped components. The technology was applied using a new generation of capillary monolithic stationary phases. Considerable peak shifts and selectivity changes were observed for given temperature conditions. The concept of temperature pulsing during an elution profile shows promise for increasing resolution in difficult separations and can provide a relatively simple means to solve coelution problems. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Verstraeten M.,Vrije Universiteit Brussel | Pursch M.,Analytical Technology Center | Eckerle P.,Analytical Technology Center | Luong J.,Analytical Technology Center | Desmet G.,Vrije Universiteit Brussel
Analytical Chemistry | Year: 2011

We report on a proof-of-principle experiment with a novel thermal modulation device with potential use in two-dimensional liquid chromatography (LC × LC) systems. It is based on the thermal desorption concept used in two-dimensional gas chromatography (GC × GC) systems. Preconcentration of neutral analytes eluting from the first dimension column is performed in a capillary "trap" column packed with highly retentive porous graphitic carbon particles, placed in an aluminum low-thermal-mass LC heating sleeve. Remobilization of the trapped analytes is achieved by rapidly heating the trap column, by applying temperature ramps up to +1200 °C/min. Compared to the nonmodulated signal, the presented thermal modulator yielded narrow peaks, and a concentration enhancement factor up to 18 was achieved. With a thermally modulated LC separation of an epoxy resin, it is shown that when the thermal modulation is applied periodically, the trapped and concentrated molecules can be released periodically and that the modulating interface can both serve as a preconcentration device and as an injector for the second dimension column of an LC × LC setup. Because of the thermal modulation, a high-molecular-weight epoxy resin could be adequately separated and the different fractions were identified with a GPC analysis, as well as an offline second dimension LC analysis. © 2011 American Chemical Society.

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