Simultaneous Determination of Major Constituents of Honeybee Venom by LC-DAD

The aim of the study was to develop an LC method for honeybee venom analysis, using cytochrome c as an internal standard. The SynChropack C8 6.5 μm, 4.6 × 100 mm column was applied. The bee venom was separated by linear gradient 5–80% B at 30 min (eluent A—0.1% TFA in water, eluent B—0.1% TFA in acetonitrile:water (80:20)). The flow rate of mobile phase was maintained at 1 mL min⁻¹, injection volume: 40 μL, separation temperature: 25 °C. The analysis was monitored at 220 nm. Several honeybee venom constituents were separated and the content of four of them (apamine, mast cell degranulating peptide, phospholipase A₂ and melittin) were determined. By applying this methodology differences in chemical composition of honeybee venom were evaluated. In order to confirm the data obtained, the following steps and parameters were taken into account for the validation of the method: selectivity, precision (injection repeatability, analysis repeatability), accuracy (recovery), linearity and operating range, limit of detection and limit of quantitation. All steps of validation proved that the developed analytical procedure was suitable for its intended purpose (standardization). Due to its simplicity, the developed method can be easily automated and incorporated into routine operations both in the bee venom identification, quality control and assay tests.

     

Simultaneous Determination of Major Constituents of Honeybee Venom by LC-DAD

The aim of the study was to develop an LC method for honeybee venom analysis, using cytochrome c as an internal standard. The SynChropack C8 6.5 μm, 4.6 × 100 mm column was applied. The bee venom was separated by linear gradient 5–80% B at 30 min (eluent A—0.1% TFA in water, eluent B—0.1% TFA in acetonitrile:water (80:20)). The flow rate of mobile phase was maintained at 1 mL min^?1, injection volume: 40 μL, separation temperature: 25 °C. The analysis was monitored at 220 nm. Several honeybee venom constituents were separated and the content of four of them (apamine, mast cell degranulating peptide, phospholipase A₂ and melittin) were determined. By applying this methodology differences in chemical composition of honeybee venom were evaluated. In order to confirm the data obtained, the following steps and parameters were taken into account for the validation of the method: selectivity, precision (injection repeatability, analysis repeatability), accuracy (recovery), linearity and operating range, limit of detection and limit of quantitation. All steps of validation proved that the developed analytical procedure was suitable for its intended purpose (standardization). Due to its simplicity, the developed method can be easily automated and incorporated into routine operations both in the bee venom identification, quality control and assay tests.     

New CZE-DAD method for honeybee venom analysis and standardization of the product

The aim of this study was to develop a new precise and accurate CZE-DAD method for honeybee venom analysis using cytochrome c as an internal standard. The 64.5 cm total length, 56 cm effective length, 75 μm ID, and 360 μm OD uncoated fused-silica capillary was used. The samples were injected into the capillary under a 50-mbar pressure for 7 s. There were 15 kV of electric field across the capillary applied. The current intensity was 26 μA. The separation was carried out at 25 °C. The analysis was run with the normal electrode polarity. The following steps and parameters were taken into account for the validation of the developed method: selectivity, precision, accuracy, linearity, limit of detection and limit of quantitation. All steps of the validation procedure proved that the developed analytical procedure was suitable for its intended purpose. Possibly this was the first study in which several honeybee venom components were separated and five of them were identified by capillary zone electrophoresis. In addition, the developed method was applied for quantitative analysis of 38 honeybee venom samples. The content (relative to the dry venom mass) of analyzed peptides in honeybee venom samples collected in 2002–2007 was as follows: apamine from 0.93% to 4.34% (mean, 2.85 ± 0.79%); mast cell degranulating peptide (MCDP) from 1.46% to 4.37% (mean, 2.82 ± 0.64%); phospholipase A₂ from 7.41% to 20.25% (mean, 12.95 ± 3.09%); melittin from 25.40% to 60.27%, (mean, 45.91 ± 9.78%). The results were compared with the experimental data obtained for the same venom samples analyzed earlier by the HPLC method. It was stated that HPCE and HPLC data did not differ significantly and that the HPCE method was the alternative for the HPLC method. Moreover, using the results obtained principal component analysis (PCA) was applied to clarify the general distribution patterns or similarities of four major honeybee venom constituents collected from two different bee strains in various months and years. PCA has shown that the strain of bee appears to be the only criteria for bee venom sample classification. Strong correlations between apamine, MCDP, phospholipase A₂, and melittin were confirmed. These correlations have to be taken into account in the honeybee venom standardization. The developed method due to its simplicity can be easily automated and incorporated into routine operations both in the bee venom identification, quality control, and standardization of the product.     

Quantitative determination of Phakellistatin 13, a new cyclic heptapeptide,in rat plasma by liquid chromatography/tandem mass spectrometry: application to a pharmacokinetic study

A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, followed by a 96-well protein precipitation, has been developed and fully validated for the determination of Phakellistatin 13 (PK13), a new cyclic heptapeptide isolated from the sponge Phakellia fusca Thiele, in rat plasma. After protein precipitation of the plasma samples (50 μL) in a 96-well plate by methanol (200 μL) containing the internal standard Pseudostellarin B (20 ng/mL), the plate was vortex mixed for 3 min. Following filtration for 5 min, the filtrate was directly injected into the LC-MS/MS system. The analytes were separated on an XB-C18 analytical column (5 μm, 50 mm × 4.6 mm i.d.) using an eluent of methanol–water (85:15, v/v) and detected by electrospray ionization mass spectrometry in the negative multiple reaction monitoring mode with a chromatographic run time of 5.0 min. The method was sensitive with a lower limit of quantification (LLOQ) of 0.1 ng/mL, with good linearity (r > 0.999) over the quantitation range of 0.1–5 ng/mL. The validation results demonstrated that this method was significantly specific, accurate, precise, and was successfully applied in measuring levels of PK13 in rat plasma following intravenous administration of 20, 50, and 100 μg/kg of peptide in rats, respectively, which was suitable for the preclinical pharmacokinetic studies on PK13.     

An improved ion chromatographic method for determination of trace levels of perchlorate in environmental water

An improved ion chromatographic (IC) method was developed to determine trace levels of perchlorate in environmental water samples. Perchlorate was separated in the hydroxide selective column IonPac AS16 using NaOH as an eluent with an organic modifier. To eliminate the coelution of perchlorate and 4-chlorobenzene sulfonate (4-CBS), an organic solvent as modifier was added to the eluent. Of four organic solvents studied, acetonitrile proved to be the most efficient based on the retention time of perchlorate and 4-CBS. To improve the method sensitivity, a concentrator column (AG19) was used to concentrate perchlorate online. With the adoption of a preconcentration step, the sensitivity of our method was improved and the method detection limit (MDL) was reduced to 0.1 μg/L. The linear range was from 0.2 μg/L to 200 μg/L with a linear correlation coefficient of 0.9989 and the relative standard deviation (RSD) of peak area for eleven successive injections of 0.5 μg/L perchlorate was 4.2%. The method had been applied to the determination of perchlorate in some real environmental water samples and recovery was between 93% and 113%. __________ Translated from Chemical Journal of Chinese Universities, 2007, 28(7), 1246–1250 [译自: 高等学校化学学报]     

RP-LC-UV Determination of Proanthocyanidins in Guazuma ulmifolia

A simple, reproducible, and efficient liquid chromatographic method was developed with UV detection. Water (0.05% TFA):acetonitrile (0.05% TFA) was used as the mobile phase in a gradient system for the determination of procyanidin B2 (PB2) and epicatechin (EC) in the bark of Guazuma ulmifolia Lam. The analysis was performed using a Phenomenex Gemini RP C₁₈ column (5 μm) as stationary phase, at 30 °C, with a flow rate of 0.8 mL min⁻¹, at a wavelength of 210 nm for detection and determination. The main validation parameters of the method were also determined. Calibration curves were found to be linear, with ranges of 20.00–150.00 (PB2) and 10.00–110.00 μg mL⁻¹ (EC). The correlation coefficients of linear regression analysis were between 0.9981 and 0.9988, and the detection limits were between 2.89 and 2.54 μg mL⁻¹. The contents of PB2 and EC were successfully determined, with satisfactory reproducibility and recovery. Recoveries of the PB2 and EC were 103.00 and 104.01%, respectively. The method was successfully applied to the determination of procyanidins in the bark of G. ulmifolia.     

Determination of selected pesticides by GC with simultaneous detection by MS (NCI) and μ-ECD in fruit and vegetable matrices

A gas chromatography–mass spectrometry method in negative chemical ionization mode has been developed incorporating simultaneous detection using a micro-electron capture detector (μ-ECD) for the determination of pesticides in fruits and vegetables. This instrument configuration uses a three-way splitter device which divides the effluent from the analytical column between the two detectors with the split ratio 1:0.1 (MSD/μ-ECD) in each run. The μ-ECD was used for confirmation purposes. Validation of the method was performed on three matrices: tomato, apple, and orange. The ethyl acetate method was assayed; recovery studies were performed at 10 and 100 μg/kg. Recoveries between 70% and 120% were achieved and relative standard deviations lower than 20% (n = 5) were obtained for all pesticides and matrices studied. Limits of quantification lower than 10 μg/kg were obtained for 100% of pesticides in all of the matrices. Limits of quantification lower than 2.5 μg/kg were achieved for 77.8% of pesticides in the tomato and apple matrices, and for 72.2% of pesticides in the orange matrix. The method showed linear response in the concentration range tested (2.5–500 μg/kg) with correlation coefficients >0.99. Good repeatability and reproducibility results were obtained in all cases, with relative standard deviations lower than 16.7% and 20%, respectively. Finally, 20 incurred samples were analyzed using the proposed method. The simultaneous use of the two detectors was satisfactory for the analysis of these real samples. The total number of pesticides identified was 25. The number of samples which contained at least one pesticide was 15—this represented 75% of the total number of samples studied.     

Determination aminopyrine in pharmaceutical formulations based on APTS-Fe3O4 nanoparticles modified glassy carbon electrode

In this work, 3-aminopropyltriethoxysilane modified Fe₃O₄ nanoparticles (ATPS-Fe₃O₄) were used to modify glassy carbon electrode for aminopyrine determination. ATPS-Fe₃O₄ showed obviously catalytic activity and adsorptivity towards aminopyrine oxidation proven by the increased oxidation peak current and the decreased oxidation peak potential. The best analytical response was obtained by immobilizing 8 μL 3 mg/mL APTS-Fe₃O₄ dispersion with an accumulation time of 200 s at −0.2 V in 0.1 M phosphate buffer solution (pH 9.0). The oxidation peak current of aminopyrine showed linear relationship with its concentration in the range from 0.5 to 100 and 100 to 1600 μM. The detection limit was 0.1 μM (S/N = 3). The proposed method showed satisfactory repeatability and anti-interference ability. The fabricated electrode was successfully applied to determine aminopyrine in pharmaceutical formulations.     

Comparative study on determination of fumagillin in fish by normal and reversed phase chromatography

Summary Fumagillin is an antibiotic agent mostly used in the veterinary profession. A normal-phase liquid chromatographic method was developed for the determination of this drug in fish matrices. A hexane-dichloromethanedioxan-2-PrOH-acetic acid (43:43:9:5:0.1 v/v %) eluent was used on a Perkin Elmer silica gel column. For validation of the process a reversed-phase HPLC method was also developed (eluent: acetonitrile-water-bicyclohyxylamine 70:30:0.05 v/v %, with Spherisorb ODS, as stationary phase). Recovery is about 100% and the limit of detection is 5 ng g⁻¹ for meat samples. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997.     

Determination of hypericin and pseudohypericin in extracts fromHypericum Perforatum L. and pharmaceutical preparations by liquid chromatography-fluorescence detection

Summary An isocratic reversed-phase liquid chromatographic method for the simultaneous determination of hypericin and pseudohypericin, two of the main constituents ofHypericum Perforatum L., has been developed. The compounds were eluted from an Inertsil ODS-3, column by triethylammonium acetate-methanol-acetonirile (5:15:80) eluent and detected fluorimetrically, excitation 478, emission 598 nm. Hypericin and pseudohypericin were extracted from flowring tops by Soxhlet and pseudohypericin was isolated from the extract by collecting its chromatographic peak from the eluent flow. Identification of peaks was by HPLC coupled to a diode array detector and electrospray MS. The method was applied to the determination of hypericin and pseudohypericin in plant extract and in pharmaceutical tablets. For the latter a solid-phase extraction procedure was adopted. Riboflavin (0.1 ng.μL⁻¹) was used as internal standard. The linear working range of the method is 0.025–4 ng.μL⁻¹ and limit of detection 0.2 ng injected on-column. A comparative SPE study for hypericin is presented.     

A validated method for the quantification of curcumin in plasma and brain tissue by fast narrow-bore high-performance liquid chromatography with fluorescence detection

Curcumin, a lipophilic polyphenol derived from the rhizome of the plant turmeric (Curcuma longa), might be useful in the prevention and treatment of a number of degenerative brain disorders, including glioma multiforma and Alzheimer’s disease. Thus, there is growing interest in measuring curcumin concentrations in the brain and other target tissues in relevant animal models. We therefore developed and validated (according to the Food and Drug Administration guidelines for bioanalytical method validation), a simple, fast and reliable method for the quantification of curcumin in biological matrices by fast high-performance liquid chromatography with fluorescence detection. This method involves a simple extraction with 95% ethyl acetate and 5% methanol, rapid separation (<2 min if external standards and <4 min if the internal standard β-estradiol 17-acetate is used) on a Jasco Reprosil-Pur Basic C₁₈ column (75 × 2 mm, 1.8 μm) with an eluent of acetonitrile, methanol, de-ionised water and acetic acid (49:20:30:1, v/v; flow rate, 0.4 mL/min) and fluorescence detection (excitation wavelength, 420 nm; emission wavelength, 470 nm). The method is selective, precise (<15% RSD at the lower limit of quantification), accurate (<15% of the coefficient of variation at the lower limit of quantification) and sensitive over a linear range of 0.05–10 μg/mL for curcumin. The developed method was used for the quantification of curcumin in the brains of mice force-fed (50 mg/kg bw) or i.p. injected (100 mg/kg bw) with curcumin. Brain curcumin concentrations of the mice were below the limit of detection at 30, 60 and 120 min after oral gavage and reached 4–5 μg/g brain 20–40 min after i.p. injection. In conclusion, the developed and validated method should be useful for the accurate and precise quantification of curcumin in target organs from relevant animal models of human diseases.     

Direct fluorescence detection of non-steroidal anti-inflammatory agents separated by TLC with 9-isothiocyanatoacridine derivatives

Summary Non-steroidal anti-inflammatory agents were separated by thin-layer chromatography, utilizing precoated plates with silica gel R as the stationary phase and chloroform:methanol:25% ammonia (80∶15∶5), as the mobile phase. The spots were visualized by spraying with 0.1% solution of 9-isothiocyantoacridine derivatives in methylene chloride or benzene and irradiating with UV at 254 and 366nm. The visual detection limit of a spot was 0.1μg.     

Capillary-Channeled Polymer (C-CP) Films as Processing Platforms for Protein Analysis by Matrix-Assisted Laser/Desorption Ionization Mass Spectrometry (MALDI-MS)

Polypropylene (PP) capillary-channeled polymer (C-CP) films have parallel, μm-sized channels that induce solution wicking via capillary action. Efficient mass transport from the solution phase to the channel surface leads to adsorption of hydrophobic protein solutes. The basic premise by which C-CP films can be used as media to manipulate analyte solutions (e.g., proteins in buffer), for the purpose of desalting or chromatographic separation prior to MALDI-MS analysis is presented here. Cytochrome c and myoglobin prepared in a Tris-HCl buffer, and ribonuclease A, lysozyme, and transferrin prepared in phosphate buffered saline (PBS), are used as the test solutions to demonstrate the desalting concept. Protein analysis is performed after deposition on a C-CP film with and without a water washing step, followed by spray deposition of a typical sinapinic acid matrix. Extracted MALDI mass spectra exhibit much improved signal-to-noise characteristics after water washing. A mixture of cytochrome c and myoglobin (2 μL of 2.5 μM each in Tris-HCl buffer) was applied, washed with water and spatially separated via simple capillary action (wicking) using a reversed-phase solvent composition of 0.1% trifluoroacetic acid (TFA) in 50:50 acetonitrile (ACN):H₂O. Subsequent application of sinapinic acid followed by imaging of the film using MALDI-MS reveals that as the protein solution is wicked down the film, separation occurs.     

Validation of the HS-GC-FID method for the determination of ethanol residue in tablets

This paper describes the validation of a HS-GC-FID method (based on the Pharmacopeia’s method) for the determination of ethanol content in tablets. A general view of the procedure development/optimization process is presented. The main point of this study is the calculation of validation parameters. Selectivity of the method was determined. Linearity (r > 0.997) was observed in the range from 9.0 to 3,040 μg of ethanol per sample (because the mass of the tablets used was around 200 mg, this corresponds to 45–15,200 μg g⁻¹). The method showed good recoveries (average 99.0%), and a relative standard deviation for repeatability and intermediate precision of 4.5% and 5.5% respectively. The limit of detection was calculated to be 3.0 μg of ethanol per sample (15 μg g⁻¹). The uncertainty budget was done according to the "Guide to the Expression of Uncertainty in Measurement" (GUM)[1], and a relative expanded uncertainty was estimated as 4.8%.     

Simultaneous voltammetric detection of dopamine and uric acid in the presence of high concentration of ascorbic acid using multi-walled carbon nanotubes with methylene blue composite film-modified electrode

An electrochemically functional nanocomposite through the adsorption of methylene blue onto the multi-walled nanotubes (MB-MWNTs) was prepared, and a sensitive voltammetric sensor was fabricated. The modified electrode showed excellent electrocatalytic activity toward dopamine (DA) and uric acid (UA) in 0.1 M phosphate solution medium (pH 3.0). Compared to the bare electrode, the MB-MWNTs film-modified electrode not only remarkably enhanced the anodic peak currents of DA and UA, i.e., shifted the anodic peak potential of DA negatively, but also avoided the overlapping of the anodic peaks of DA and UA. The interference of ascorbic acid (AA) was eliminated. Under the optimized conditions, the peak separation between AA and DA and between DA and UA was 219 and 174 mV, respectively. In the presence of 1.0 mM AA and 10.0 μM UA, the anodic peak current was linear to the concentration of DA in the range of 0.4–10.0 μM with a detection limit of 0.2 μM DA. The anodic peak current of UA was linear to the concentration in the range of 2.0–20.0 and 20.0–200.0 μM with a lowest detection limit of 1.0 μM in the presence of 1.0 mM AA and 1.0 μM DA.     

Measurement uncertainty evaluation and in-house method validation of the herbicide iodosulfuron-methyl-sodium in water samples by using HPLC analysis

A method for separation and quantitative determination of the iodosulfuron-methyl-sodium in water samples by high-performance liquid chromatography (HPLC) was developed and in-house validated in order to demonstrate its performance for monitoring of heterogeneous photocatalytic elimination of the herbicide iodosulfuron-methyl-sodium from water. Surface and ground water samples were used to demonstrate its selectivity, detection and quantification limits, linearity, trueness and precision. In addition, stability of iodosulfuron-methyl-sodium was studied in function of temperature and time. Method accuracy was quantified through measurement uncertainty estimate based on method validation data. The paper gives practical and easy to follow guidance on how uncertainty estimates can be obtained from method validation experiments. It shows that, if properly planned and executed, key precision and trueness studies undertaken for validation purposes can also provide much of the data needed to produce an estimate of measurement uncertainty. Our analytical protocol allowed us to quantify iodosulfuron-methyl-sodium in ground water and surface water in concentration level between 2.50–50.0 μmol L⁻¹ with satisfactory recoveries (99–104%) and repeatability lower or equal than 0.3% for all the matrices. We also estimated within-laboratory reproducibility over 3-month period, which was 0.7%. We proved that the method was selective for determination of iodosulfuron-methyl-sodium in the relevant matrices. Measurement uncertainty of results was evaluated to be 4.0% with 95% confidence level. After validation and measurement uncertainty evaluation steps, results obtained showed that the method can be applied to efficiently monitor heterogenous photocatalytic degradation of the herbicide iodosulfuron-methyl-sodium.     

Multisyringe flow injection spectrophotometric determination of uranium in water samples

A multisyringe flow injection analysis method for the determination of uranium in water samples was developed. The methodology was based on the complexation reaction of uranium with arsenazo (III) at pH 2.0. Uranium concentrations were spectrophotometrically detected at 649 nm using a light emitting diode. Under the optimized conditions, a linear dynamic range from 0.1 to 4.0 μg mL⁻¹, a 3σ detection limit of 0.04 μg mL⁻¹, and a 10σ quantification limit of 0.10 μg mL⁻¹ were obtained. The reproducibility (%) at 0.5, 2.5, and 4.0 μg mL⁻¹ was 2.5, 0.9, and 0.6%, respectively (n = 10). The interference effect of some ions was tested. The proposed method was successfully applied to the determination of uranium in water samples.     

Amperometric biosensor based on tyrosinase immobilized in hydrotalcite-like compounds film for the determination of polyphenols

A tyrosinase (Tyr) biosensor has been constructed by immobilizing tyrosinase on the surface of Mg–Al–CO₃ hydrotalcite-like compound film (HTLc) modified glassy carbon electrode (GCE) for the determination of polyphenols. The negatively charged tyrosinase was adsorbed firmly on the surface of a positively charged HTLc/GCE by electrostatic interactions and retained its activity to a great degree. The modified electrode was characterized by cyclic voltammetry and AC impedance spectra. Polyphenols were determined by a direct reduction of biocatalytically generated quinone species. The different parameters, including pH, temperature, and enzyme loading were investigated and optimized. Under the optimum conditions, Tyr/HTLc electrode gave a linear response range of 3–300, 0.888–444, and 0.066–396 μM with a detection limit (S/N = 3) of 0.1, 0.05, and 0.003 μM for catechol, caffeic acid, and quercetin, respectively. In addition, the repeatability and stability of the enzyme electrode were estimated. Total polyphenol contents of real samples were also determined to study the potential applicability of the Tyr/HTLc/GCE biosensor.     

Multi-walled carbon nanotubes as solid-phase extraction adsorbent for the ultra-fast determination of chloramphenicol in egg, honey, and milk by fused-core C18-based high-performance liquid chromatography–tandem mass spectrometry

In the present work, a high-performance liquid chromatography–tandem mass spectrometry method has been developed for the residue analysis of chloramphenicol (CAP) in several food matrices. Following the addition of D₅-CAP as internal standard, egg, honey, and milk were extracted and cleaned by means of solid-phase extraction, utilizing multi-walled carbon nanotubes as sorbent. The extracts were separated on a Halo fused-core C18 column (50 mm × 2.1 mm, 2.7 μm) and quantified by a 4000 Q-trap mass spectrometer equipped with a TurboIonSpray™ interface using electrospray ionization and multiple-reaction monitoring mode. The method validation was performed according to the criteria of Commission Decision 2002/657/EC. The decision limit (CCα) and detection capability (CCβ) of CAP in milk were calculated for m/z 320.8 > 151.9. Due to the existence of slight signal suppression, quantification was performed by matrix-matched calibration curves, ranging from 0.1 to 100 ng mL⁻¹, with regression coefficients of 0.9993, 0.9998, and 0.9997 for egg, honey, and milk, respectively. Mean recoveries of the CAP ranged from 95.8% to 102.3%, with the corresponding intra- and inter-day variation (relative standard deviation) less than 7.13% and 8.89%, respectively. The limit of detection and limit of quantification of the method were also reported. This method successfully applied to several food matrixes (egg, honey, and milk) and can serve as a monitoring tool to avoid unacceptable levels of residues of CAP entering the food chain.     

Separation and quantitation of oxprenolol in urine and pharmaceutical formulations by HPLC using a Chiralpak IC and UV detection

Abstract  

A stereoselective HPLC method has been developed for the simultaneous determination of oxprenolol enantiomers in urine and pharmaceutical products. Enantiomeric resolution of oxprenolol was achieved on cellulose tris(3,5-dichlorophenylcarbamate) immobilized onto a 5 μm spherical porous silica chiral stationary phase (CSP) known as Chiralpak IC with UV detection at 273 nm. The mobile phase consisted of n-hexane:isopropanol:triethylamine 70:30:0.1 (v/v/v) at a flow rate of 1.0 cm³/min. The method was validated for its linearity, accuracy, precision, and robustness. The calibration curves were linear over the range of 0.5–75 μg/cm³, with a detection limit of 0.1 μg/cm³ for each enantiomer. An average recovery of 99.0% and a mean relative standard deviation of 2.6% at 40.0 μg/cm³ for S-(−)- and R-(+)-enantiomers were obtained. The overall recoveries of oxprenolol enantiomers from pharmaceutical formulations were in the range 97.5–99.0%, with RSDs ranging from 0.6 to 0.8%. The mean extraction efficiency of oxprenolol from urine was in the range of 86.0–93.0% at 0.5–5 μg/cm³ for each enantiomer. The assay method proved to be suitable as a chiral quality control for oxprenolol formulations using HPLC and for therapeutic drug monitoring.