ABSTRACT
We report on a comparative study of the basic separation kinetics of commercial packed bed columns and a micro-pillar array column (µPAC) working in the 1-10µL/min flow rate range, i.e., operating in the area of capillary flow LC. This is done using a basic test mixture of 8 alkylphenones under both isocratic and gradient separation conditions. Care was taken the µPAC and the packed bed columns have similar volumes (around 10µL) and hence also similar t0-times when compared at the same flow rate. In addition, the isocratic mobile phase composition and gradient programs were selected such to have similar elution windows (in absolute times) for all 4 column types. It was found that the µPAC produces significantly more theoretical plates (up to 3 times) in the 1-4µL/min range, while, the packed bed columns perform better at the higher flow rates because of the relatively large inter-pillar distance in the µPAC. Under gradient conditions, the µPAC produces a clearly higher peak capacity than any of the three packed bed columns over the entire range of investigated flow rates, albeit that this is also partly to be owed to the steeper gradient that needed to be used in the µPAC in order to maintain a similar elution window on all columns.
Subject(s)
Chromatography, High Pressure Liquid/methods , Kinetics , PressureABSTRACT
In the current paper, an axial rearrangement mixer is studied. The mixer aims to flatten out occasional composition fluctuations originating from the pump. In a first phase, dispersion in a single mixer channel is investigated using pulses introduced by a dedicated injection pulse generator. The mixing in the single channel is studied for different flow rates and a model is presented based on the experimental data. Next, the resulting signal for the whole mixer is studied.
