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In this study, a cross-H-channel interface was constructed for coupling flow injection with capillary electrophoresis (FI-CE) to reduce sample requirement and sensitivity loss in the typical FI-CE. Based on this cross-H-channel interface, a new FI-CE system was established, in which sample introduction was performed by directly injecting sample solution along a thin capillary (50 μm, i.d.) to the interface from an injection syringe. The sample requirement was reduced distinctly and usual sample dilution in the sample transport process was obviously decreased, thereby spontaneously enhancing the sensitivity. Moreover, because of the unique construction of the cross-H-channel interface, field amplified sample stacking (FASS) and high-speed CE were skillfully combined to further improve the sensitivity and to shorten separation time. The versatility of this new FI-CE was demonstrated by determination of ephedrine (E) and pseudoephedrine (PE) in human urine. Up to 45 repeated injections per hour and clearly baseline separation of E and PE in less than 1 min were achieved, giving limits of detection (LODs) of 0.23 and 0.21 μg mL(-1) for E and PE, respectively, and yielding relative standard deviation (RSD) values of the migration time and the peak height (n=5) of 2.6% and 3.1% for E, 2.3% and 3.3% for PE, respectively. In contrast to typical FI-CE, approximately 8-250-fold decreases in sample volume requirement, 7-fold shortening in separation time and 50-fold improvements in sensitivity were obtained.

Herein we report the first example of exploring bio-based materials, palm fibers (PFs), as a stationary phase for capillary gas chromatographic separations. The PFs capillary column was fabricated by the sol-gel coating method and showed a weak polar nature and high column efficiency over 4699 plates per m for n-dodecane, naphthalene and n-octanol. Importantly, the column exhibited high selectivity and resolving capability for more than a dozen mixtures covering a wide-ranging variety of analytes and isomers. In addition, it was applied for the determination of isomer impurities in real samples, proving its good potential for practical gas chromatographic analysis. Experimental Materials and equipmentAll the chemicals were of analytical grade. Tetraethoxysilane (TEOS), poly(methylhydrosiloxane) (PMHS) and triuoroacetic acid (TFA, 95%) were purchased from J

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