This article presents a new, simple and rapid continuous separation method by combination of flow injection with capillary electrophoresis designed for the analysis of basic traditional Chinese medicines. The device was produced using commercial capillary and components readily available in analytical laboratory. In double-T configuration, the designed horizontal separation channel was 25 microm i.d. x 146 mm length (an effective separation length of 93 mm) quartz capillary, with two vertical elicitation arms produced from 0.5 mm i.d. pump tubing. The capillary was embedded in a 40 x 20 x 3 mm organic glass base. Using the double-T configuration, continuous introduction of a series of samples was achieved. More than 3.00 resolution for ephedrine and pseudo-ephedrine were obtained using 100 mm borate buffer (pH 9.80) within 8 min in 25 microm separation channel with an electrical field strength of 137 V/cm (UV detection at 215 nm). The linear calibration range was 50-1500 microg/mL (ephedrine, r = 0.9982; pseudo-ephedrine, r = 0.9990) for both analytes. The limits of detection were 2.65 micro g/mL for ephedrine and 2.92 microg/mL for pseudo-ephedrine. In this device, the contents of ephedrine and pseudo-ephedrine in five Chinese medicinal preparations were determined with RSDs (n = 5) in range 1.16-4.51% and recoveries in range 90.4-114.6%.
The determination of three aconitine alkaloids (hypaconitine, aconitine, mesaconitine) in five traditional Chinese medicines including two Tibetan medicines, Chuanwu, Caowu, Fuzi, Aconitum Tanguticum Maxim and Aconitum Gymnandrum Maxim by non-aqueous capillary electrophoresis using a new recording mode is described. The dissociation constants of aconitine, mesaconitine and hypaconitine have also been determined by CZE and were 7.71, 6.60 and 6.25, respectively. The separation was achieved by optimizing the applied voltage, the pH and the concentration of the buffer. The electrophoretic medium was 20 mM borax-70% (v/v) methanol (pH 8.5) and an uncoated capillary (50 cm x 75 microm i.d.) was used. Detection was carried out with a UV monitor at 214 nm. The total time for separation and determination was under 13 min.
At the present paper, an analytical method based on temperature controlled solid-liquid extraction (TC-SLE) utilizing a synthesized ionic liquid, (N-butylpyridinium hexafluorophosphate, [BPy]PF 6 ), as solid solvent and phenanthroline (PT) as an extractant was developed to determine micro levels of Fe 2+ in tea by PT spectrophotometry. TC-SLE was carried out in two continuous steps: Fe 2+ can be completely extracted by PT-[BPy]PF 6 or back-extracted at 80˝C and the two phases were separated automatically by cooling to room temperature. Fe 2+ , after back-extraction, needs 2 mol/L HNO 3 as stripping agent and the whole process was determined by PT spectrophotometry at room temperature. The extracted species was neutral Fe(PT) m Cl 2 (m = 1) according to slope analysis in the Fe 2+ -[BPy]PF 6 -PT TC-SLE system. The calibration curve was Y = 0.20856X´0.000775 (correlation coefficient = 0.99991). The linear calibration range was 0.10-4.50 µg/mL and the limit of detection for Fe 2+ is 7.0ˆ10´2 µg/mL. In this method, the contents of Fe 2+ in Tieguanyin tea were determined with RSDs (n = 5) 3.05% and recoveries in range of 90.6%-108.6%.
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