Screening for library-assisted identification and fully validated quantification of 22 beta-blockers in blood plasma by liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization

A liquid chromatographic-mass spectrometric assay with atmospheric pressure chemical ionization (LC-APCI-MS) is presented for screening for, library-assisted identification (both in scan mode) and quantification (selected-ion mode) of the beta-blockers acebutolol, diacetolol, alprenolol, atenolol, betaxolol, bisoprolol, bupranolol, carazolol, carteolol, carvedilol, celiprolol, esmolol, labetalol, metoprolol, nadolol, nebivolol, oxprenolol, penbutolol, propranolol, sotalol, talinolol and timolol in blood plasma after mixed-mode (HCX) solid-phase extraction (SPE) and separation by reverse-phase liquid chromatography with gradient elution. The validation data were within the required limits. The assay was successfully applied to authentic plasma samples allowing confirmation of diagnosis of overdose situations as well as monitoring of patients' compliance.     

Simple, rapid, and sensitive determination of beta-blockers in environmental water using dispersive liquid-liquid microextraction followed by liquid chromatography with fluorescence detection

A novel method, dispersive liquid-liquid microextraction combined with liquid chromatography-fluorescence detection is proposed for the determination of three beta-blockers (metoprolol, bisoprolol, and betaxolol) in ground water, river water, and bottled mineral water. Some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, pH, and salt effect were investigated and optimized. In the method, a suitable mixture of extraction solvent (60 μL carbon tetrachloride) and dispersive solvent (1 mL acetonitrile) were injected into the aqueous samples (5.00 mL) and the cloudy solution was observed. After centrifugation, the enriched analytes in the bottom CCl(4) phase were determined by liquid chromatography with fluorescence detection. Under the optimum conditions, the enrichment factors (EFs) for metoprolol, bisoprolol, and betaxolol were 180, 190, and 182, and the limits of detection (LODs) were 1.8, 1.4, and 1.0 ng L(-1) , respectively. A good linear relationship between the peak area and the concentration of analytes was obtained in the range of 3-150 ng L(-1) . The relative standard deviations (RSDs) for the extraction of 10 ng L(-1) of beta-blockers were in the range of 4.6-5.7% (n = 5). Compared with other methods, dispersive liquid-liquid microextraction is a very simple, rapid, sensitive (low limit of detection), and economical (only 1.06 mL volume of organic solvent) method, which is in compliance with the requirements of green analytical methodologies.     

Analysis by liquid chromatography-electrospray ionization tandem mass spectrometry and acute toxicity evaluation for beta-blockers and lipid-regulating agents in wastewater samples

This paper describes a multiresidue method for the extraction and determination of two therapeutic groups of pharmaceuticals, lipid-regulating agents (clofibric acid, bezafibrate, gemfibrocil, fenofibrate) and beta-blockers (atenolol, sotalol, metoprolol, betaxolol) in waters by solid-phase extraction followed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). Recoveries obtained from spiked HPLC water, as well as, from spiked real samples (sewage treatment plants influent and effluents, river and tap water) were all above 60%, with the exception of betaxolol with a 52% recovery. The quantitative MS analysis was performed using a multiple reaction monitoring. The LC-MS-MS method gave detection limits ranging from 0.017 to 1.25 microg/l in spiked effluent. Precision of the method, calculated as relative standard deviation, ranged from 3.7 to 18.5%. Individual and combined effects on Daphnia magna were evaluated for both therapeutic groups. Individual effects in culture medium showed these compounds as not harmful and not toxic, an exception is fenofibrate that was found to be harmful, but at high, in the environment unrealistic concentrations (EC50 of 50 mg/l). Combined effect in wastewater showed synergistic toxic effects at low concentration level (2 microg/l).     

Quantitative structure-retention and retention-activity relationships of beta-blocking agents by micellar liquid chromatography

Sixteen beta-blocking agents (acebutolol, alprenolol, atenolol, bisoprolol, carteolol, celiprolol, esmolol, labetalol, metoprolol, nadolol, oxprenolol, pindolol, practolol, propranolol, sotalol and timolol) showing a large range of hydrophobicity (octanol-water partition coefficients, log P between -0.026 and 2.81) were subjected to micellar liquid chromatography with sodium dodecyl sulfate as micelle forming agent, and n-propanol as organic modifier. The correlation between log P and the retention factor extrapolated to a mobile phase free of micelles and organic modifier was investigated. The use of an interpolated retention factor or the retention factor for specific individual experimental mobile phases was however advantageous since the retention factors of all beta-blocking agents were measurable in the selected mobile phases. Good correlations with log P and with in vitro biological parameters (cellular permeability coefficients in Caco-2 monolayers and apparent permeability coefficients in rat intestinal segments) were found.     

以L-酒石酸正己酯-硼酸配合物作为反相液相色谱手性流动相添加剂拆分5种β-受体阻滞剂

本文以L-酒石酸正己酯-硼酸配合物为手性流动相添加剂,建立了普萘洛尔、艾司洛尔、美托洛尔、比索洛尔、索他洛尔和阿替洛尔六种β-受体阻滞剂的反相高效液相色谱手性分离方法。对影响对映体分离的主要因素：L-酒石酸正己酯、硼酸浓度,缓冲溶液种类、浓度、pH值和有机改性剂-甲醇含量等进行了详细考察。最佳色谱条件为：Venusil MP-C18色谱柱（4.6 mm × 250 mm,5 μm）,流动相为15 mmol/L乙酸铵-甲醇（体积比为20: 80或30: 70,含60 mmol/L硼酸,70 mmol/L L-酒石酸正己酯,醋酸调节pH值6.00）,检测波长214 nm。在最佳分离条件下,五对对映体（普萘洛尔、艾司洛尔、美托洛尔、比索洛尔、索他洛尔）可以分别获得基线分离。     

Technetium-99 in the Rhône river water

⁹⁹Tc a pure -particle emitter with long half-life (T=2.13×10⁵ y) was measured in Rhône river water and in Mediterranean sea water near the river mouth. The values obtained in the Rhône river allowed us to show the downstream distribution of the effluents from the nuclear fuel reprocessing plant of Marcoule: the⁹⁹Tc activity which is low above the plant, 0.016 mBq 1^–1, is 0.4 mBq 1^–1 at Roquemaure, located 14 km below the plant, and then decreases as a function of distance from the plant.     

Improvement of peak shape and separation performance of beta-blockers in conventional reversed-phase columns using solvent modifiers

A comparative study of peak shape, elution behavior, and resolution of 16 beta-blockers (acebutolol, alprenolol, atenolol, bisoprolol, carteolol, celiprolol, esmolol, labetalol, metoprolol, nadolol, oxprenolol, pindolol, practolol, propranolol, sotalol, and timolol) chromatographed with hybrid mobile phases of triethylamine (TEA)-acetonitrile and sodium dodecyl sulfate (SDS)-propanol is performed using conventional reversed-phase columns and isocratic elution. Both solvent modifiers (TEA and SDS) prevent the interaction of the basic drugs with the alkyl-bonded phase. However, the protection mechanisms of silanols on the packing are different. Whereas TEA associates with the silanol sites (blocking ion-exchange processes or repelling the solutes), the long hydrophobic chain of SDS is inserted in the bonded organic layer with the sulfate group protruding outside, which makes the stationary phase negatively charged. The effects of TEA, acetonitrile, SDS, and propanol on the elution strength, efficiency, peak asymmetry, and resolution are examined under an experimental design basis that is assisted by computer simulation to reach more general conclusions. The combination of improved peak shapes, larger selectivity, and a smaller range in retention among compounds of extreme polarity leads to the observation that a greater number of beta-blockers can be resolved with a hybrid micellar system.     

Direct Resolution of Six Beta Blockers into their Enantiomers on Silica Plates Impregnated with l-Asp and l-Glu

JPC – Journal of Planar Chromatography – Modern TLC - Resolution of racemic metoprolol, propranolol, carvedilol, bisoprolol, salbutamol, and labetalol, commonly used ß-blockers,...     

Detection of equimolar EDTA and DTPA in spiked wastewater effluents

Ethylenediaminetetraacetic acid (EDTA) and diethylenetriamine-pentaacetic acid (DTPA) are water ‘softening’ agents that are present in numerous household and industrial detergents. Since these particular chelating agents are not significantly degraded during conventional wastewater treatment processes, wastewater treatment plant (WTP) effluents can contain up to 19 µM of EDTA and 7 µM of DTPA. Little, however, is known about the release of EDTA and DTPA from WTPs to rivers. To gain insight, we here report on the development of a cost-effective analytical method. This method is based on the chromatography of a humic acid-cadmium (HA-Cd) complex on a size-exclusion chromatography column (SEC, Sephadex G-15) while using WTP effluents from Lethbridge, Banff and Canmore which contained 10 mM Tris-buffer as the mobile phase (pH 8.2). The intact HA-Cd complex is detected by means of a flame atomic absorption spectrometer (FAAS). The addition of equimolar EDTA and DTPA up to 10 µM allowed us to observe a concentration-dependent increase of the retention time of the main Cd-peak. This behaviour was qualitatively comparable between the WTP effluents and was rationalised by the EDTA/DTPA-mediated mobilisation of Cd from the HA-Cd complex. The signal intensity that corresponded to the mobilised Cd was used to establish calibration curves with corresponding correlation coefficients in the range of 0.950–0.978. Therefore, the developed method yields robust results for realistic concentrations of equimolar EDTA/DTPA in real WTP effluents. The developed method can now be applied to analyse real WTP effluent for the presence of chelating agents, whose concentrations may be expressed as being equivalent to a particular equimolar EDTA/DTPA concentration.     

Chiral separation of β-adrenergic blockers on CelluCoat column by HPLC

The chiral separation of 10 β-adrenergic blockers (acebutalol, alprenolol, bufuralol, bisoprolol, celiprolol, carazolol, indenolol, metoprolol, oxprenolol and propranolol) was achieved on CelluCoat column (250 mm × 4.6 mm, 5 μm particle size). The mobile phases used were (90:10:0.2, v/v/v) and (95:5:0.2, v/v/v) combinations of n-heptane-ethanol-diethylamine, respectively. The flow rates were 0.5, 1.0 and 2.0 mL min⁻¹ with detection at 225 nm. The capacity (k), selectivity (α) and resolution (R_s) factors were 0.44-12.91, 1.12-2.19 and 1.00-9.50, respectively. The proposed supra-molecular models indicated that the chiral resolution were governed by π-π interactions, hydrogen bondings and steric effect.     

Determination of pharmaceuticals in river water by column switching of large sample volumes and liquid chromatography–diode array detection,assisted by chemometrics: An integrated approach to green analytical methodologies

An analytical method for the simultaneous determination of nine β-blockers (sotalol atenolol, nadolol, pindolol, metoprolol, timolol, bisoprolol, propanolol and betaxolol) and two analgesics (paracetamol and phenazone) in river water by liquid chromatography and diode array detection is reported. The method involves a modified precolumn switching methodology replacing the small precolumn with a short C18 liquid chromatography column (50 mm × 4.6 mm, 5 μm particle size), thus allowing the preconcentration of large water sample volumes whereas interferences eluting at the first of the chromatogram were discarded to waste. This approach allowed to preconcentrate 30 mL river water samples, modified with 0.4% MeOH, achieving univariate method detection and determination limits ranged between 0.03 and 0.16 μg L⁻¹ and between 0.2 and 0.5 μg L⁻¹, respectively, with precision values lower than 9.4% for spiking levels at the quantitation limits of each analyte and lower than 4.0%, except bisoprolol (8.3%), for higher spiking levels (1.0 μg L⁻¹ of all analytes). Matrix background was reduced in three way data by a baseline correction following the Eilers methodology, whereas multivariate curve resolution and alternating least squares in combination with the standard addition calibration method, applied to these data, coped with overlapping peak, systematic (additive) and proportional (matrix effect) errors. The method was successfully applied for the determination of the target pharmaceuticals in river water from three places in a river stream with acceptable recoveries and precision values, taking into account the complexity of the analytical problem. The joint statistical test for the slope and the intercept of the linear regression between the nominal concentration values versus those predicted, showed that the region computed contained the theoretically expected values (0) for the intercept and (1) for the slope (at a confidence level of 95%), which indicates the absence of both constant and proportional errors in the predicted concentrations.     

Evaluation of teicoplanin chiral stationary phases of 3.5 and 5 microm inside diameter silica microparticles by polar-organic mode capillary electrochromatography

Different types of fused-silica capillaries of 75 microm inside diameter (ID) were packed, namely type A and B, and evaluated for the direct resolution of racemates of several basic compounds by enantioselective capillary electrochromatography (e-CEC). Type A was packed with a chiral stationary phase (CSP) containing teicoplanin (TE) mixed with silica microparticles (3:1 w/w) while type B contained only the TE-CSP. In both cases, particles of different sizes (3.5 and 5 microm ID) were employed. A polar-organic mobile phase containing methanol-acetonitrile (60-40% v/v and 0.05% w/v ammonium acetate was used. Several beta-blockers (alprenolol, oxprenolol, metoprolol, pindolol, salbutamol, propranolol, atenolol, acebutolol) were baseline-enantioresolved with both capillary types, in very short times.     

Fast and sensitive analysis of beta blockers by ultra‐high‐performance liquid chromatography coupled with ultra‐high‐resolution TOF mass spectrometry

This paper presents a method for the determination of acebutolol, betaxolol, bisoprolol, metoprolol, nebivolol and sotalol in human serum by liquid–liquid extraction and ultra‐high‐performance liquid chromatography coupled with ultra‐high‐resolution TOF mass spectrometry. After liquid–liquid extraction, beta blockers were separated on a reverse‐phase analytical column (Acclaim RS 120; 100 × 2.1 mm, 2.2 μm). The total run time was 6 min for each sample. Linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery and sample stability were evaluated. The method was successfully applied to the therapeutic drug monitoring of 108 patients with hypertension. This method was also used for determination of beta blockers in 33 intoxicated patients.     

Stereoisomer analysis of wastewater-derived beta-blockers, selective serotonin re-uptake inhibitors, and salbutamol by high-performance liquid chromatography-tandem mass spectrometry

A reversed-phase enantioselective liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method was developed to measure enantiomer fractions (EF) and concentrations of pharmaceuticals in wastewater. Enantiomer resolution of six beta-blockers (atenolol, metoprolol, nadolol, pindolol, propranolol, and sotalol) along with two selective serotonin re-uptake inhibitors (citalopram, fluoxetine) and one beta(2)-agonist (salbutamol) was achieved with the Chirobiotic V stationary phase. Analyte recovery averaged 86% in influent and 78% in effluent with limits of detection ranging from 0.2 to 7.5 ng/L. These results represent an improvement in wastewater EF measurement for atenolol, metoprolol and propranolol as well as the first EF measurements of citalopram, fluoxetine, nadolol, pindolol, salbutamol and sotalol in wastewaters. Changes in EF through treatment indicate biologically mediated stereoselective processes were likely occurring during wastewater treatment.     

Development,validation and analytical error function of two chromatographic methods with fluorimetric detection for the determination of bisoprolol and metoprolol in human plasma

This work describes two high-performance liquid chromatographic methods for the individual determination of bisoprolol and metoprolol in human plasma. Analytical methods involve two different liquid-liquid extractions of human plasma, with diethyl ether for bisoprolol and with dichloromethane for metoprolol, coupled with a similar Nucleosil C(18) reversed-phase HPLC column. Fluorimetric detection was used to identify both beta-blockers. Retention times for bisoprolol and metoprolol were 8.7 and 3.2 min, respectively. Linear regressions for the calibration curves were linear at a concentration range of 6.25-200 ng/mL. Intra- and inter-day precision coefficients of variations and accuracy bias were acceptable (within 15%) over the entire range for both drugs. Average recovery was 89% for metoprolol and 98% for bisoprolol. Once the methods had been validated, analytical error functions were established as standard deviation (SD; ng/mL) = 2.216 + 3.608 x 10(-4)C(2) (C = theoretical concentration value) and SD-(ng/mL) = 0.408 + 0.378 x 10(-1)C for bisoprolol and metoprolol, respectively. The methods developed and their associated analytical error functions will be suitable for pharmacokinetic studies and for determination of plasma concentration if posology individualization of these drugs is needed.     

Development and validation of an HPLC‐UV method for the simultaneous determination of the antipsychotics clozapine,olanzapine and quetiapine,several beta‐blockers and their metabolites

A simple, accurate and selective column‐switching high‐performance liquid chromatography (HPLC) method was developed and validated for simultaneous quantification of six beta ‐blockers (metoprolol, timolol, bisoprolol, propranolol, carvedilol and nebivolol), three of their metabolites (α ‐hydroxy metoprolol, N‐ desisopropyl propranolol and 4′‐hydroxy carvedilol 4‐HCAR), three antipsychotics (olanzapine, clozapine and quetiapine) and three of their metabolites (N‐ desmethyl olanzapine, N‐ desmethyl clozapine and N‐ desalkyl quetiapine) in human serum. After pretreatment on a Merck LiChrospher RP‐4 ADS column (25 μm), drugs were separated on a Phenomenex Gemini Phenyl Hexyl 110 A column (250 × 4.6 mm, 5 μm) using a gradient mixture of acetonitrile and potassium dihydrogen phosphate buffer pH 3.1 (containing 10% methanol) as a mobile phase at a flow rate of 1 mL/min. The total analysis time was 40 min. For detection of the analytes, four different UV wavelengths were used: 215, 226, 242 and 299 nm. The method was validated according to the guidelines of the Society of Toxicology and Forensic Chemistry in terms of selectivity, linearity, accuracy, precision and stability and successfully applied for the analysis of the 15 described analytes in human serum.     

Determination of β-adrenoreceptor antagonists in urine by high-performance liquid chromatography with diode-array spectrophotometric detection

The determination of pindolol, oxprenolol and propranolol in human urine is described. The drugs are isolated with a GDX-502 resin-packed column, separated on a C₁₈ (5-μm) reversed-phase column with methanol/aqueous acetic acid as mobile phase and quantified with diode-array spectrophotometric detector. The recovery was > 93%, and detection limits were 2 ng for pindolol, 12 ng for oxprenolol and 2 ng for propranolol. Results are given for urine from healthy volunteers who had received the drugs orally.     

Preparation and characterization of microporous fibers for sample preparation and LC‐MS determination of drugs

The aim of this study was the preparation of polypyrrole (PPy) fibers for solid phase microextraction (SPME). PPy coatings were obtained during the electrochemical polymerization process. The utility of various metal wires (Fe, Cu, Ag, Cu/Ag, kanthal and medical stainless steel) as a support for polymers was compared. Various experimental conditions of the synthesis process such as scan rate, voltage limits and number of scans and deposition time were applied. The average polymer thickness was in the range of 7–125 μm and its weight was in the scope of 0.65–5.6 mg. Different techniques, mainly elemental analysis, Fourier transform infrared spectroscopy, microscopy, and chromatography were performed for the characterization of obtained fibers with microporous structure. The extraction efficiency of cardiovascular drugs (metoprolol, propranolol, oxprenolol, propafenone and mexiletine) by means of fibers was tested. The concentration of mentioned compounds in standard solution was in the span of 10–150 ng/mL. LC‐MS was employed for determination of drugs in desorption solution. LODs varied from 0.013 to 1.51 ng/mL for metoprolol and mexiletine respectively. The repeatability of extraction was obtained with the RSD values lower than 10%.     

Supercritical fluid extraction combined with solid phase extraction as sample preparation technique for the analysis of β-blockers in serum and urine

A method is developed for the determination of β-blockers in serum and urine at levels of 0.5 μg/mL. The technique uses a combination of solid phase extraction (SPE) with in situ derivatization and supercritical fluid extraction (SFE) with subsequent gas chromatography mass spectrometry. The optimization of the SFE step shows that a static extraction period can be eliminated. The method gives good linearity (r = 0.991–0.999) and repeatability in the concentration range of 0.5 to 5 μg/mL. Relative standard deviations for oxprenolol, propanolol and metoprolol were less than 5% in serum and 5–11% in urine. Received: 23 May 1997 / Revised: 28 July 1997 / Accepted: 5 August 1997     

Methods for the determination of neutral drugs as well as betablockers and β2-sympathomimetics in aqueous matrices using GC/MS and LC/MS/MS

An analytical method has been developed which allows the determination of 22 different neutral and weakly basic drugs belonging to several different medicinal classes like antiphlogistics, betablockers, β₂-sympathomimetics, lipid regulators, antiepileptic agents, psychiatric drugs and vasodilators in waste water as well as in river and drinking water. A method including solid phase extraction, derivatization by silylation and detection by GC/MS permits detection down to 5 ng/L. The recovery rates mostly exceeded 70%. However, the determination of phenazone, carbamazepine, cyclophosphamide, ifosfamide and pentoxiphylline is frequently disturbed by organic co-extractants in real samples of rivers and waste waters. Therefore, a time saving alternative method has been developed, combining solid phase extraction (as an enrichment step) together with detection by LC-electrospray/MS/MS allowing the measurement of 5 neutral drugs. Detection limits down to 10 ng/L have been achieved even for organically highly contaminated waters like sewage treatment plant effluents. Received: 18 November 1997 / Revised: 18 March 1998 / Accepted: 21 March 1998