PubMed · 10795417
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S A Phillips, R Hiley. Workshop on explosives trace analysis methods.. https://doi.org/10.1016/s1355-0306(99)72058-7
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The possibility to perform shear-driven chromatographic separations in micro-channels is demonstrated, using a novel laser-jet printed microfluidic channel system. The obtained theoretical plate numbers are in fair agreement with the theoretical calculations. Theoretical extrapolations of the separation speeds and detection limits which can be achieved when further miniaturizing the current system are presented as well.
A series of micro-monolithic columns with different porosities were prepared for capillary electrochromatography (CEC) by in-situ copolymerization of butyl methacrylate, ethylene glycol dimethacrylate, and 2-acrylamido-2-methyl-1-propane-sulfonic acid in the presence of a porogen in fused-silica capillaries of 100 microm I.D. Different column porosities were obtained by changing the ratios of monomers to porogenic solvents. Columns were investigated and evaluated under both pressure-driven (high-performance liquid chromatography, HPLC) and electro-driven (capillary electrochromatography, CEC) conditions. Each column exhibited different efficiency and dependency on flow velocity under electro-driven conditions. Abnormally broad peaks for some relatively bulky molecules were observed. Possible explanations are discussed. The differences in column efficiency and retention behavior between the two eluent-driven modes were studied in detail. In addition, other column properties, such as morphology, porosity, stability and reproducibility, were extensively tested.
Four isoflavone components were purified from soybean extract by high-speed counter-current chromatography (HSCCC). Two types of multilayer coil separation columns were used: a small column made of standard 2.6-mm I.D. PTFE (polytetrafluoroethylene) tubing with a 260-ml capacity and a large column of convoluted PTFE tubing of 5.7-mm average I.D. with a 1,200-ml capacity. Separation was performed with a two-phase solvent system composed of hexane-ethyl acetate-1-butanol-methanol-acetic acid-water (1:2:1:1:5:1, v/v) by eluting the lower aqueous phase at 2 ml/min (small column) and 5 ml/min (large column) at a revolution speed of 700 rpm. From 500 mg of crude sample the small column yielded 33 mg of daidzin, 41 mg of genistin, 27 mg of 6''-O-malonyldaidzin and 24 mg of 6"-O-malonylgenistin. The large convoluted column separated, from 3 g of crude sample, 203 mg of daidzin, 241 mg of genistin, 158 mg of 6''-Omalonyldaidzin and 135 mg of 6"-O-malonylgenistin all at over 90% purity. The convoluted tubing facilitated preparation of a large multilayer coil due to its high flexibility.