Comparison of various reversed-phase columns for the simultaneous determination of ephedrines in urine by high-performance liquid chromatography

Imaz, C.; Navajas, Rosana; Carreras, Daniel; Rodríguez, C.; Rodriguez, A.F.

doi:10.1016/s0021-9673(99)00903-6

Cited by 36 publications

(10 citation statements)

References 5 publications

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“…In order to make CE effluent contact the electrode surface directly, the distance between the Pt working electrode and the outlet of the capillary was controlled strictly in the range 100 AE 5µm with the aid of an optical microscope. 300 mL Ru(bpy) 3 2+ solution was added to the reservoir before analysis and was replaced every 3h to eliminate any depletion effect or potential interference from reactions during analysis. The capillary was always flushed with 0.1mol/L NaOH overnight, followed by rinsing with distilled water for 30min at the first use.…”

Section: Experimental Procedures Of Ce-eclmentioning

confidence: 99%

“…The intensity of the emitted light had significant correlation with the rate of the oxidation of the ECL reagent, Ru(bpy) 3 2+ , and the oxidation rate was related to the voltage of the working…”

Section: Optimization Of Detection Voltagementioning

confidence: 99%

“…Unfortunately, the background current increased significantly when its concentration was too high. Therefore, it was essential to determine a signal:noise ratio (S:N) that was optimized with Ru(bpy) 3 2+ concentrations. In this study, 5mmol/L Ru(bpy) 3 2+ was found to produce optimal S:N values and was used in the experiments described.…”

Section: +mentioning

confidence: 99%

“…Since the ECL reaction of Ru(bpy) 3 2+ with alkylamine depends on the buffer pH to a great extent (24), the ECL intensity as a function of the buffer pH value in the range 7.0-10.0 (0.5 as a unit) was investigated. The ECL intensity increased in the pH range 7.0-8.5 and then decreased at buffer pH values>8.5.…”

Section: Optimization Of Detection Buffermentioning

confidence: 99%

“…In particular, electrochemiluminescence (ECL) detection involving tris(2,2-bipyridyl) ruthenium (II) [Ru(bpy) 3 2+ ] offers other merits, such as wide linear range, no derivatization and good selectivity for nitrogen-containing compounds (12)(13)(14). Therefore, analytical procedures combining CE separation with Ru(bpy) 3 2+ -based ECL detection have been successfully applied to determine many alkaloids (15)(16)(17). However, as far as we know, such a CE-ECL procedure has not been reported for the determination of ephedrine.…”

Section: Introductionmentioning

confidence: 99%

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Capillary electrophoresis coupled with end‐column electrochemiluminescence for the determination of ephedrine in human urine, and a study of its interactions with three proteins

Yang

Zeng

et al. 2011

Luminescence

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A tris(2,2-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺)-based electrochemiluminescence (ECL) detection coupled with capillary electrophoresis (CE) method has been established for the sensitive determination of ephedrine for the first time. Under the optimized conditions [ECL detection at 1.15 V, 25 mmol/L phosphate buffer solution (PBS), pH 8.0, as running buffer, separation voltage 12.5 kV, 5 mmol/L Ru(bpy)₃²⁺ with 60 mmol/L PBS, pH 8.5, in the detection cell] linear correlation (r = 0.9987) between ECL intensity and ephedrine concentration was obtained in the range 6.0 × 10⁻⁸-6.0 × 10⁻⁶ g/mL. The detection limit was 4.5 × 10⁻⁹ g/mL (S:N = 3). The developed method was successfully applied to the analysis of ephedrine in human urine and the investigation of its interactions with three proteins, including bovine serum albumin (BSA), cytochrome C (Cyt-C) and myoglobin (Mb). The number of binding sites and the binding constants between ephedrine and BSA, Cyt-C and Mb were 8.52, 12.60, 10.66 and 1.55 × 10⁴ mol/L, 6.58 × 10³ mol/L and 1.59 × 10⁴ mol/L, respectively.

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Section: Experimental Procedures Of Ce-eclmentioning

confidence: 99%

Section: Optimization Of Detection Voltagementioning

confidence: 99%

Section: +mentioning

confidence: 99%

Section: Optimization Of Detection Buffermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Capillary electrophoresis coupled with end‐column electrochemiluminescence for the determination of ephedrine in human urine, and a study of its interactions with three proteins

Yang

Zeng

et al. 2011

Luminescence

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Simultaneous quantification of six ephedrines in a Mahwang preparation and in urine by high‐performance liquid chromatography

Chan

Pan²,

Hsu³

2005

Biomedical Chromatography

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A rapid and reliable high-performance liquid chromatographic method was developed and validated for the simultaneous determination of norephedrine (NE), norpseudoephedrine (NPE), ephedrine (E), pseudoephedrine (PE), methylephedrine (ME) and methylpseudoephedrine (MPE) in both a Mahwang traditional Chinese medicine (TCM) preparation and in urine using alpha-ethylbenzylamine as the internal standard. The method uses a Spherisorb C(18) column for an isocratic elution in a tetraethylammoniumphosphate-methanol mobile phase at a wavelength of 206 nm. The limits of detection of NE, NPE, E, PE, ME and MPE in sample solutions ranged from 0.1 to 0.3 microg[sol ]mL at a signal-to-noise ratio of 3. The within-day precision as calculated from the Mahwang TCM preparation and urine samples was below 6.2 and 1.4% for each analyte. The between-day precision as calculated from the Mahwang TCM preparation and urine samples was below 6.8 and 5.9% for each analyte. The between-day accuracy as determined from the Mahwang TCM preparation and urine samples was below 2.2 and 6.8% for each analyte. The recoveries for six compounds, obtained with compounds spiked into the Mahwang TCM preparation and urine, were found to be more than 93.6%. This method can be successfully applied to doping and excretion rate studies.

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Simultaneous chiral separation and determination of ephedrine alkaloids by MEKC‐ESI‐MS using polymeric surfactant I: Method development

et al. 2007

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In this work, simultaneous separation of eight stereoisomers of ephedrine and related compounds ((+/-)-ephedrine, (+/-)-pseudoephedrine, (+/-)-norephedrine and (+/-)-N-methylephedrine) was accomplished using a polymeric chiral surfactant, i.e. polysodium N-undecenoxycarbonyl-L-leucinate (poly-L-SUCL) by chiral (C)MEKC-ESI-MS. The conditions of CMEKC were first investigated. The baseline separation of all eight stereoisomers of ephedrine and related compounds was achieved under optimum CMEKC conditions (35 mM poly-L-SUCL, 15 mM NH(4)OAc, pH 6.0, 30% v/v ACN, 30 kV and 20 degrees C) in less than 30 min. Next, a central composite design for response surface modeling has been described to evaluate the electrospray chamber parameters and the sheath liquid conditions. Optimum mass abundance of stereoisomers of ephedrine and related compounds was observed using the spray chamber parameters, namely 250 degrees C drying gas temperature and 8 L/min drying gas flow rate at a nebulizer pressure of 4 psi. Furthermore, the experimental design indicates that the optimum mass abundance of the stereoisomers of ephedrine and related compounds can be obtained using a sheath liquid containing 80:20 v/v methanol-water, 5 mM NH(4)OAc at pH 8.5 delivered at 5 microL/min. Finally, compared to MEKC-UV, the use of poly-L-SUCL in MEKC-MS provided significantly higher sensitivity for stereoisomers of ephedrine and related compounds.

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Comparison of various reversed-phase columns for the simultaneous determination of ephedrines in urine by high-performance liquid chromatography

Cited by 36 publications

References 5 publications

Capillary electrophoresis coupled with end‐column electrochemiluminescence for the determination of ephedrine in human urine, and a study of its interactions with three proteins

Capillary electrophoresis coupled with end‐column electrochemiluminescence for the determination of ephedrine in human urine, and a study of its interactions with three proteins

Simultaneous quantification of six ephedrines in a Mahwang preparation and in urine by high‐performance liquid chromatography

Simultaneous chiral separation and determination of ephedrine alkaloids by MEKC‐ESI‐MS using polymeric surfactant I: Method development

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