ABSTRACT
Microchip electrophoresis with fluorescence detection has been applied for fast separation and determination of ephedra alkaloids in pharmaceutical formulations and body fluids. A custom epifluorescence microscope setup was employed and the compounds were separated within 40 s, allowing the detection of less than 200 ng/L for both analytes. Quantitation of the two stimulants was performed via a derivatization step using FITC without any extraction or preconcentration steps. The effects of different microchip types and excitation light sources were investigated and the method was successfully applied for the analysis of these compounds in tablet formulations, yielding recovery rates from 100.2 to 101.1% and relative standard deviations from 1.5 to 3.4%. Analysis of ephedrines was also carried out with human urine samples at detection limits of 500-1000 ng/L and relative standard deviations from 2.2 to 3.3% using argon ion LIF detection.
Subject(s)
Alkaloids/analysis , Alkaloids/chemistry , Electrophoresis, Microchip/methods , Ephedra/chemistry , Fluorescein-5-isothiocyanate/analysis , Pseudoephedrine/analysis , Urine/chemistry , Alkaloids/urine , Body Fluids/chemistry , Ephedrine/analysis , Ephedrine/chemistry , Ephedrine/urine , Equipment Design , Fluorescence , Humans , Microfluidic Analytical Techniques/methods , Pharmaceutical Preparations/analysis , Pseudoephedrine/urine , Spectrometry, Fluorescence/methods , Tablets/analysisABSTRACT
Microchip electrophoresis (MCE) with native fluorescence detection has been applied for the fast quantitative analysis of pharmaceutical formulations. For this purpose, methods for fast separation and sensitive detection of the unlabeled diuretic drugs, amiloride, triamterene, bendroflumethiazide (BFMTZ), and bumetanide were developed. An epifluorescence setup was used enabling the coupling of different lasers into a commercial fluorescence microscope. The detection sensitivity of different excitation light sources was compared utilizing either a HeCd laser (lambda(exc) = 325 nm), a frequency quadrupled Nd:YAG laser (lambda(exc) = 266 nm), or a mercury lamp (lambda(exc) = 330-380 nm). At optimal conditions using the HeCd laser, the drugs were separated within 15 s with LODs less than 1 mug/mL for the four compounds. A linear relationship between concentration and peak area was obtained in the concentration range of 0.05-20 microg/mL with a mean correlation coefficient of around 0.996 for all analytes. The method was successfully applied to the analysis of the respective drugs in commercial formulations and in human urine without interference from other constituents. These data show that MCE has a great potential for reliable drug analysis.
Subject(s)
Diuretics/analysis , Diuretics/urine , Electrophoresis, Microchip/methods , Amiloride/analysis , Amiloride/urine , Bendroflumethiazide/analysis , Bendroflumethiazide/urine , Bumetanide/analysis , Bumetanide/urine , Fluorescence , Humans , Lasers , Light , Spectrometry, Fluorescence , Tablets , Triamterene/analysis , Triamterene/urineABSTRACT
Channels in microfluidic glass chips manufactured with the alternative powder blasting technology were permanently coated with poly(vinyl alcohol) (PVA) in order to improve the performance in microchip electrophoresis. The performance of coated and uncoated powder-blasted (pb) devices as well as coated and uncoated wet chemical etched (wc) chips was compared in electrophoretic separations of fluorescently labeled test compounds. The limited electrophoretic resolution obtained in pb-chips could significantly be improved by coating the channels with PVA. The resolution of test compounds in such coated pb-devices was even higher than in uncoated wc-chips. PVA-coated pb-chips could also successfully be applied in chiral separations. While in an uncoated pb-chip using a cyclodextrins buffer only one broad signal was obtained, two well-resolved signals were obtained in a coated device.
