Determination of ephedrines in urine by high-performance liquid chromatography

A Modified 1H-NMR Quantification Method of Ephedrine Alkaloids in Ephedrae Herba Samples

A previous 1H-NMR method allowed the quantification of ephedrine alkaloids; however, there were some disadvantages. The cyclized derivatives resulted from the impurities of diethyl ether were identified and benzene was selected as the better extraction solvent. The locations of ephedrine alkaloids were confirmed with 2D NMR. Therefore, a specific 1H-NMR method has been modified for the quantification of ephedrine alkaloids. Accordingly, twenty Ephedrae Herba samples could be classified into three classes: (I) E. sinica-like species; (II) E. intermedia-like species; (III) others (lower alkaloid contents). The results indicated that ephedrine and pseudoephedrine are the major alkaloids in Ephedra plants, but the concentrations vary greatly determined by the plant species and the collection locations.

Preliminary Phytochemical Screening, Quantitative Analysis of Alkaloids, and Antioxidant Activity of Crude Plant Extracts from Ephedra intermedia Indigenous to Balochistan

The aim of this study was to evaluate the antioxidant activity, screening the phytogenic chemical compounds, and to assess the alkaloids present in the E. intermedia to prove its uses in Pakistani folk medicines for the treatment of asthma and bronchitis. Antioxidant activity was analyzed by using 2,2-diphenyl-1-picryl-hydrazyl-hydrate assay. Standard methods were used for the identification of cardiac glycosides, phenolic compounds, flavonoids, anthraquinones, and alkaloids. High performance liquid chromatography (HPLC) was used for quantitative purpose of ephedrine alkaloids in E. intermedia. The quantitative separation was confirmed on Shimadzu 10AVP column (Shampack) of internal diameter (id) 3.0 mm and 50 mm in length. The extract of the solute in flow rate of 1 ml/min at the wavelength 210 nm and methanolic extract showed the antioxidant activity and powerful oxygen free radicals scavenging activities and the IC50 for the E. intermedia plant was near to the reference standard ascorbic acid. The HPLC method was useful for the quantitative purpose of ephedrine (E) and pseudoephedrine (PE) used for 45 samples of one species collected from central habitat in three districts (Ziarat, Shairani, and Kalat) of Balochistan. Results showed that average alkaloid substance in E. intermedia was as follows: PE (0.209%, 0.238%, and 0.22%) and E (0.0538%, 0.0666%, and 0.0514%).

Identification of Isomeric Ephedrines by Cold Ion UV Spectroscopy: Toward Practical Implementation

Ephedrine and pseudoephedrine are stimulant drugs whose use is prohibited in athletic competition by the World Anti-Doping Agency (WADA) at very different threshold doping violation concentrations. We use a recently developed universal approach that integrates UV photofragmentation spectroscopy of cold ions with Orbitrap mass spectrometry (MS) for highly selective and highly sensitive identification of these diastereomers. Both species can be selectively detected at a solution concentration of a few tens of ng/mL, which is almost 3 orders of magnitude lower than the threshold concentration required by WADA. Relative concentrations of the isomers in solutions have been determined with the standard deviation of 3.1%, when the ions were cooled in an ion trap maintained at T = 6 K. Considering practical implementation of the method, we evaluated its performance for a simplified instrumentation. At an affordable elevated temperature of ∼70 K and with a low-maintenance midbandwidth optical parametric oscillator, a few second measurement should yield nearly the same selectivity and only ten times lower sensitivity than with the current research grade instrument.

Nutritional supplements: prevalence of use and contamination with doping agents

Based upon recent sales numbers, nutritional supplements play a key role in the lifestyle of a substantial proportion of the population. As well as products such as vitamins or minerals, several precursors of anabolic steroids are marketed as nutritional supplements. Another group of commercially available supplements are products for weight loss based upon herbal formulations originating from Ephedra species. Apart from supplements indicating the presence of these active compounds, numerous non-hormonal nutritional supplements were found that were contaminated with non-labelled anabolic steroids. Stimulating agents other than naturally occurring analogues of ephedrine were detected. A major group using dietary supplements are sportsmen, ranging from amateur level to elite athletes. Besides the possible health risks associated with the use of dietary supplements, athletes should take care not to violate the rules of the World Anti-Doping Agency because athletes remain responsible for substances detected in their biofluids, irrespective of their origin. Several analytical methods have been developed to determine the presence of doping agents as contaminants. The present review attempts to address the issues concerning the use of nutritional supplements and the detection of doping agents as contaminants in dietary supplements.

Optimization of normal-phase chromatographic separation of compounds with primary, secondary and tertiary amino groups

The retention behavior of primary, secondary and tertiary amines was studied using normal-phase-HPLC on silica, diol, and cyano stationary phases. Several classes of amines, including benzylamines, anilines, ephedrines, tryptamines, and azatryptamines were chromatographed using mixtures of hexane and ethoxynonafluorobutane with methylene chloride and methanol. Peak tailing, diminished selectivity and low plate count were minimized by the addition of volatile amines to the mobile phase. The optimal additive was n-propylamine at 0.1% concentration. On diol columns, the elution order of free primary, N-N-methyl, and N,N-dimethylamines was predictable, while the elution order of primary and secondary amines on cyano columns varied depending on the alcohol modifier concentration. The feasibility of preparative normal-phase chromatography was demonstrated by the separation of a mixture of primary, secondary and tertiary amines obtained by direct methylation of norephedrine. The procedures described may provide a practical alternative to traditional methods of analysis and purification of potential drug candidates.

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

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.

Effect of 1-alkyl-3-methylimidazolium-based ionic liquids as the eluent on the separation of ephedrines by liquid chromatography

The chromatographic behavior of ephedrines (norephedrine, ephedrine, pseudoephedrine and methylephedrine) on a C18 column was studied with different concentrations of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquids as the eluent at pH 3.0. The addition of ionic liquid has great effects on the separation of these basic compounds: decreasing band tailing, reducing band broadening, and improving resolution. The retention times of the analytes increase at first and then decrease with the increase in the concentration of ionic liquid. This effect may be attributed to the competition between imidazolium cations and the polar groups of the analytes for the silanol group on the alkylsilica surface, and also to the formation of weak bilayer electronic structure on the C18 column. Several ionic liquids with different alkyl substituents on the imidazolium cations or with different counterions as the eluents were compared.

Quantification of ephedrines in urine by column-switching high-performance liquid chromatography

A method for the quantification of five congener ephedrines in urine samples without sample preparation was developed. The analytes were trapped on a C18 precolumn and separated on a C18 BDS analytical column. Baseline separation was achieved for all analytes. The method meets the requirements of the International Olympic Committee (IOC) medical commission regarding cut-off limits for positive doping cases with ephedrines.

Simultaneous quantitation of ephedrines in urine by gas chromatography-nitrogen-phosphorus detection for doping control purposes

A gas chromatographic method for the simultaneous quantitation of ephedrine, pseudoephedrine, norephedrine (phenylpropanolamine), norpseudoephedrine (cathine) and methylephedrine in urine is described. The method consists of a liquid-liquid extraction with tert.-butyl methyl ether at pH 14. The extracts are analysed on a GC system equipped with an Rtx-5 Amine column and a nitrogen-phosphorus detector. Method validation shows excellent separation, linearity, specificity, accuracy, precision, intra-laboratory repeatability and reproducibility, making the method especially suitable for quantitation of ephedrines in urine samples for doping control purposes. A statistical analysis on the abuse of the different ephedrines in urine from athletes controlled in the Flemish doping control laboratory during the period 1993-2000 is included.

HPLC determination of phenylpropanolamine in pharmaceutical preparations using 4-dimethylaminobenzaldehyde as a derivatizing reagent

A method is described for the high performance liquid chromatographic (HPLC) determination of phenylpropanolamine (PPA) based on precolumn derivatization with 4-dimethylaminobenzaldehyde (DAB) and elution from phenomenex C-18 column with methanol-water and detection by spectrophotometry at 418 nm. Linear calibration was obtained with 9.4--46.9 microg ml(-1) with a detection limit of 4.7 ng ml(-1). Vitamin B(12) and rifampicin when present together with PPA separated completely and could be determined simultaneously. PPA was determined in pharmaceutical preparations with a relative standard deviation of 0.6--1.6%.

Determination of ephedrines in urine by gas chromatography-mass spectrometry

A selective gas-liquid chromatographic method with mass spectrometry (GC-MS) for the simultaneous confirmation and quantification of ephedrine, pseudo-ephedrine, nor-ephedrine, nor-pseudoephedrine, which are pairs of diastereoisomeric sympathomimetic amines, and methyl-ephedrine was developed for doping control analysis in urine samples. O-Trimethylsilylated and N-mono-trifluoroacetylated derivatives of ephedrines--one derivative was formed for each ephedrine--were prepared and analyzed by GC-MS, after alkaline extraction of urine and evaporation of the organic phase, using d3-ephedrine as internal standard. Calibration curves, with r2>0.98, ranged from 3.0 to 50 microg/ml depending on the analyte. Validation data (specificity, % RSD, accuracy, and recovery) are also presented.

Sensitive determination of ephedrine and norephedrine in human plasma samples using derivatization with 9-fluorenylmethyl chloroformate and liquid chromatography

A high-performance liquid chromatography procedure for the determination of ephedrine and norephedrine using fluorimetric detection in plasma samples is described. A double liquid-liquid extraction was performed, followed by derivatization with 9-fluorenylmethyl chloroformate. The extracts were chromatographed with a 5-microm C18 (150x4.6 mm I.D.) column using a mobile phase composed of acetonitrile and water (52:48; v/v). The excitation and emission wavelengths were respectively 264 nm and 313 nm. Calibration curves were linear over the range 0 to 300 ng/ml for each analyte. The specificity of the method was demonstrated with several FMOC-reacting drugs. The limits of quantification are similar to those obtained with the reference method: 2 ng/ml for ephedrine and 5 ng/ml for norephedrine. This method has been successfully applied to the determination of ephedrine and norephedrine plasma levels after administration of low doses of ephedrine to healthy subjects.

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

Different reversed-phase columns for basic analytes were compared for the simultaneous determination of ephedrines in urine, such as LiChrospher 60 RP-Select B, LiChrospher 100 RP18, Hypersil BDS-C18, Inertsil ODS-2, Spherisorb ODS-B and Symmetry Shield RP8. Symmetry Shield was the only column which did not require the use of high concentrations of buffer and triethylamine. With this column, a good separation of the six ephedrines and the internal standard was achieved using 50 mM phosphate buffer-25 mM triethylamine as a mobile phase. Linearity, precision and accuracy were satisfactory for the levels usually found in urine. Due to these all parameters the developed analytical method was found to be suitable for the application in the doping field.

Quantitative determination of acrivastine and pseudoephedrine hydrochloride in pharmaceutical formulation by high performance liquid chromatography and derivative spectrophotometry

In this study, fourth derivative spectrophotometry and high performance liquid chromatography (HPLC) have been used and described for the quantitative determination of acrivastine (I) and pseudoephedrine hydrochloride (II) in their pharmaceutical capsules form (Duact). In the former method, d4A/d gamma 4 values were measured in methanol at 315 and 269 nm for (I) and (II) respectively. The relative standard deviations (RSD) for the method were found to be 1.16% for (I) and 0.94% for (II). The latter method based on reversed phase HPLC system using LiChrosorb C18 analytical column. The mobile phase used for separation of (I), (II) and internal standard (p-hydroxymethylbenzoate) were the water/acetonitrile/methanol/perchloric acid/n-octylamine (500:130:25:13:0.3 v/v) and the detection of the compounds in the capsules were at 260 nm using UV detector. The RSD for the HPLC method were determined to be 0.79 and 0.88% for (I) and (II) respectively. The proposed methods, which give thoroughly comparable data, are simple, rapid, and allow precise and accurate results and could be used for commercial formulations containing acrivastine and pseudoephedrine hydrochloride in combination.

Development and validation of a high-performance liquid chromatography method for the determination of cold relief ingredients in chewing gum

An isocratic high-performance liquid chromatography (HPLC) method for the simultaneous determination of the active compounds paracetamol, pseudoephedrine and chlorpheniramine in chewing gum samples has been developed and validated. The method required a simple liquid-liquid extraction using n-hexane and a mixture of water-acetonitrile prior to HPLC analysis. The chromatographic separation was achieved with an aqueous solution containing hexylamine (pH 3)-acetonitrile as the mobile phase, a Spherisorb C18 column and UV detection at 220 nm. As an application, the proposed method has been used to evaluate the release into saliva of these compounds from samples under a controlled human chewing process.

Do synthetic adrenergic agents interfere with the measurement of endogenous plasma catecholamine concentrations?

PURPOSE

It is common to administer synthetic sympathomimetic and sympatholytic agents in the intensive care unit and operating room. The present study examines whether such agents, as well as the products of catecholamine metabolism, interfere with the quantitation of endogenous catecholamines by high-performance liquid chromatography.

METHODS

Samples of drugs and metabolites were assayed before and after alumina extraction and their relative retention times were compared with dopamine, norepinephrine, and epinephrine relative retention times. Blood samples from patients receiving these drugs were also assayed for their interferences with catecholamine determination.

RESULTS

Phenylephrine interfered with the quantitation of epinephrine. Isoproterenol's peak was so delayed it appeared in the following chromatogram. Dobutamine had two small peaks in vitro, whereas in the patient samples only one peak was identified; the other was probably masked by the dopamine peak. Labetalol had one peak when the pure drug was assayed but multiple peaks in patient samples, that were probably caused by metabolites of labetalol.

CONCLUSION

Synthetic adrenergic agents and catecholamine metabolites can potentially interfere with the quantitation of the endogenous catecholamines. Thus, it is important to examine whether such interference occurs when conducting high-performance liquid chromatography assays.

Simultaneous quantification of ephedrines in urine by high-performance liquid chromatography

A high-performance liquid chromatographic method for the simultaneous determination of ephedrine, pseudoephedrine, phenylpropanolamine, norpseudoephedrine and methylephedrine in urine is described. Samples were extracted at basic pH into diethyl ether and then back extracted into a small volume of acetic acid. These extracts were chromatographed on a Phase Sep Spherisorb ODS 1 column with tetraethylammoniumphosphate-methanol mobile phase and the analytes were detected by UV absorbance at 214nm. Calibration curves were linear over the range 0.5-100 microgram/ml for each analyte. The selectivity of the method was demonstrated for several drugs found with the ephedrines in pharmaceutical formulations. This method has an excellent accuracy, precision and recovery for all the ephedrine at the cut-off concentrations as set by the IOC for a positive doping case and can thus be used to quantify these ephedrines when present in the urine obtained from sportspersons.