Imprinted ß-ketoenamine-linked covalent organic frameworks as dispersive sorbents for the fluorometric determination of timolol.

Timolol accompanied the formation of fluorescent ß-ketoenamine-linked covalent organic frameworks (COFs) via the Sc(Tof)3-catalyzed condensation of derivated carbaldehyde and hydrazide in a 1,4-dioxane/mesitylene porogen to construct timolol-imprinted COFs (TICOFs). With high imprinting factors, the synthesis-optimized TICOFs were characterized by fluorescence, UV-Vis spectrometry, X-ray diffraction, N2 adsorption/desorption analyses, scanning electron microscopy, and FTIR spectrometry. The TICOF fluorescence measured at 390 nm/510 nm is dynamically quenched by timolol and was thus utilized to quantify timolol in a linear range of 25-500 nM with a LOD of 8 nM. The TICOF recovered 99.4% of 0.5% timolol maleate in a commercial eye drop (RSD = 1.1%, n = 5). In addition, TICOF was used as a dispersive sorbent to recover 95% of 2.0 nM timolol from 20 mg of TICOF in 25 mL phosphate buffer. Dilution factors of 25 and 75 were the maximum tolerated proportions of the urine and serum matrix spiked with 2.0 nM timolol to reach recoveries of 92.4% and 90.3%, respectively.

Undeclared Doping Substances are Highly Prevalent in Commercial Sports Nutrition Supplements.

Sports nutrition supplements have previously been reported to contain undeclared doping substances. The use of such supplements can lead to general health risks and may give rise to unintentional doping violations in elite sports. To assess the prevalence of doping substances in a range of high-risk sports nutrition supplements available from Dutch web shops. A total of 66 sports nutrition supplements - identified as potentially high-risk products claiming to modulate hormone regulation, stimulate muscle mass gain, increase fat loss, and/or boost energy - were selected from 21 different brands and purchased from 17 web shops. All products were analyzed for doping substances by the UK life sciences testing company LGC, formerly known as the Laboratory of the Government Chemist, using an extended version of their ISO17025 accredited nutritional supplement screen. A total of 25 out of the 66 products (38%) contained undeclared doping substances, which included high levels of the stimulants oxilofrine, ß-methylphenethylamine (BMPEA) and N,ß-dimethylphenethylamine (NBDMPEA), the stimulant 4-methylhexan-2-amine (methylhexaneamine, 1,3-dimethylamylamine, DMAA), the anabolic steroids boldione (1,4-androstadiene-3,17-dione) and 5-androstene-3ß,17α-diol (17α-AED), the beta-2 agonist higenamine and the beta-blocker bisoprolol. Based upon the recommended dose and the potential variability of analyte concentration, the ingestion of some products identified within this study could pose a significant risk of unintentional doping violations. In addition to inadvertent doping risks, the prescribed use of 3 products (4.5%) could likely impose general health risks.

Differential potential ratiometric sensing platform for enantiorecognition of chiral drugs.

A versatile, robust and efficient differential potential ratiometric sensing platform was developed for enantioselective recognition of dual chiral targets based on a composite membrane of molecularly imprinted polymers (MIPs) and reduced graphene oxide (rGO) modified glassy carbon electrode (GCE). The functional chitosan-based MIPs and rGO were compatibly immobilized on the GCE with high selectivity and efficient signal amplification. Moreover, via the systematic optimization of series conditions, a distinct potential difference (PD), reaching 135 mV, was obtained between the R-/S-prop based on the MIPs/rGO/GCE. In a controllable concentration range from 50 µM to 1000 µM, different ratios of R-/S-prop were linearly related to the peak potentials (Eps) in the racemic mixture. Using this low-cost reversible electrochemical platform, both Prop enantiomers were simultaneously identified with high repeatability and time-based stability. This novel semi-quantitative electrochemical sensing platform was established to rapidly quantify the ratio of S-/R-prop by Ep for the chiral drug recognition with great potential for practical applications in fields of pharmacological detection and clinical analysis.

Polycaprolactone nanofibers functionalized with a dopamine coating for on-line solid phase extraction of bisphenols, betablockers, nonsteroidal drugs, and phenolic acids.

Polycaprolactone composite nanofibers coated with a polydopamine layer are introduced as a new type of absorption material for on-line solid phase extraction (SPE) in chromatographic system. A hybrid technology combining the electrospinning and melt blowing was used for the preparation of 3D-structured microfiber/nanofibrous polycaprolactone composite. The dopamine coating was then applied to functionalize the micro/nanofibers. Polydopamine-coated polycaprolactone fibers were tested as an extraction phase in on-line SPE prior to HPLC separation and UV detection. Four groups of biologically active substances including bisphenols (Bisphenol S, Bisphenol AF, Bisphenol A, Bisphenol C, Bisphenol AP, Bisphenol Z, Bisphenol BP, and Bisphenol M), betablockers (Timolol, Metoprolol, Labetalol, and Propranolol), nonsteroidal antiphlogistic drugs (Salicylic acid, Ketoprofen, Naproxen, Indomethacin, Diclofenac, Ibuprophen, and Meclofenamic acid), and phenolic acids (Chlorogenic acid, Caffeic acid, Sinapic acid, m-Coumaric acid, Benzoic acid, and Cinnamic acid) were used as the model analytes. Neat and coated fibers were compared and applied as sorbents for the on-line extraction set-up. Both materials produced good extraction potential for the determination of bisphenols and nonsteroidal drugs in model biological and environmental samples including river water, human urine, and blood serum. However, the polydopamine layer significantly increased the extraction efficiency of polar drugs. Typical repeatability of on-line extraction procedure on polydopamine coated fibers was in the range 0.12-4.11% for bisphenols, 0.55-1.41% for antiphlogistic drugs, 0.59-2.52% for phenolic acids, and 1.01-1.65% for betablockers. Graphical abstract Schematic representation of polycaprolactone composite nanofibers coated with a polydopamine layer as an advanced absorption material for on-line solid phase extraction in chromatography.

Analysis of 27 ß-Blockers and Metabolites in Milk Powder by High Performance Liquid Chromatography Coupled to Quadrupole Orbitrap High-Resolution Mass Spectrometry.

This paper presents an application of high performance liquid chromatography coupled with quadrupole orbitrap high-resolution mass spectrometry (HPLC-Q-Orbitrap HRMS) for the analysis of 27 ß-blockers and metabolites in milk powder. Homogenized milk power samples were extracted by acetonitrile and purified by using Oasis PRiME HLB solid-phase extraction cartridges. The Ascentis® C8 chromatographic column was used to separate the analytes. The quantification was achieved by using matrix-matched standard calibration curves with carazolol-d7 and propranolol-d7 as the internal standards. The results show an exceptional linear relationship with the concentrations of analytes over wide concentration ranges (0.5⁻500 µg kg-1) as all the fitting coefficients of determination r² are > 0.995. All the limits of detection (LODs) and quantitation (LOQs) values were within the respective range of 0.2⁻1.5 µg kg-1 and 0.5⁻5.0 µg kg-1. Overall average recoveries were able to reach 66.1⁻100.4% with the intra- and inter-day variability under 10%. This method has been successfully applied to the screening of ß-blockers and metabolites in commercial milk powders. At the same time, the corresponding characteristic fragmentation behavior of the 27 compounds was explored. The characteristic product ions were determined and applied to the actual samples screening.

A versatile HPLC method with an isocratic single mobile phase system for simultaneous determination of anti-glaucoma formulations containing timolol.

Timolol is a non-cardioselective beta blocker and has different combined ophthalmic dosage forms for treatment of glaucoma. This research introduce an HPLC method for the separation of three drugs used in combination with timolol simultaneously by applying isocratic mobile phase system in a single run and the same detection wavelength with short time. The drugs included in the separation procedures are; dorzolamide, brinzolamide, and brimonidine. The HPLC method was carried out through a single mobile phase system, which contains acetonitrile: 0.05M phosphate buffer at the ratio of 30:70, respectively at pH 3.5 and wavelength of 220nm. The method, regarding its simplicity allows determination of the studied drugs simultaneously using single run in about 8minutes. The method was rectilinear in the ranges of concentration: 1.25-25µg/mL for timolol, 4-80µg/mL for dorzolamide, 5-50µg/mL for brinzolamide and 2-20µg/mL for brimonidine. Different factors affecting the separation are thoroughly studied. The developed method was validated based on the official guidelines and the results were compared statistically with previously published methods and showed non-significant difference.

Bioassay, determination and separation of enantiomers of atenolol by direct and indirect approaches using liquid chromatography: A review.

Atenolol, a ß-adrenergic receptor antagonist, is a chiral compound used for the treatment of cardiovascular diseases and to treat hypertension, coronary heart disease, arrhythmias, sinus tachycardia and myocardial infarction, where it acts preferentially upon the ß-adrenergic receptors in the heart. It is marketed as a racemate, but only the (S)-enantiomer of (RS)-atenolol is responsible for the ß-adrenoceptor blocking activity. Different chromatographic methods have been applied for the separation and determination of enantiomers. In this article a review is presented on liquid chromatographic methods for enantioseparation of (RS)-atenolol by both direct and indirect approaches involving practical applications of several chiral stationary phases, chiral derivatization reagents and ligand exchange and impregnation methods. These include methods using both HPLC and TLC for separation, determination and bioassay of enantiomers of atenolol. In addition, some aspects of enantioseparation under achiral phases of liquid chromatography have been briefly mentioned as applicable to (RS)-atenolol. This review provides current available enantioseparation choices not only for (RS)-atenolol but also for other applicable racemic drugs.

Preconcentration of ß-blockers using functionalized ordered mesoporous silica as sorbent for SPE and their determination in waters by chiral CE.

A method for simultaneous separation and determination of four enantiomeric pairs of ß-blockers in waters by chiral CE has been developed. Off-line SPE was employed using functionalized ordered mesoporous silica as sorbent. Separation by CE was achieved using a BGE composed by methylated-ß-CD (1.25% w/v) dissolved in a 50 mM phosphate buffer (pH 2.5) and 30°C, with good chiral resolution for all enantiomers. Mesoporous silica functionalized with octadecyl groups (denoted SBA15-C18) was prepared by a postsynthesis method and applied for the preconcentration of atenolol, propranolol, metoprolol, and pindolol enantiomers in waters by off-line SPE. Under optimized conditions, a preconcentration factor of 300 was achieved, employing 100 mg of SBA15-C18 as sorbent, with recoveries between 96 and 105% in tap water and good repeatability (% RSD = 7-11%, n = 6). Commercial C18 amorphous silica (ExtraBondR C18 ) was also tested as sorbent for SPE, but results revealed better extraction capacity with higher recoveries for the SBA15-C18 material. The analytical characteristics of the off-line SPE-chiral CE method were evaluated, showing good precision, linearity, and accuracy with method quantification limits between 5.3 and 13.7 µg/L for all enantiomers. The SBA15-C18 material allowed the extraction of four enantiomeric pairs of ß-blockers spiked in tap water, river water, and ground water with recoveries between 58 and 105%.

RP-HPLC enantioseparation of ß-adrenolytics using micellar mobile phase without organic solvents.

Enantioseparation of a few commonly administered racemic ß-adrenolytics (namely, carvedilol, betaxolol, salbutamol and bisoprolol) has been achieved using a water micellar mobile phase containing surfactants (sodium dodecyl sulphate and Brij-35) without organic solvents as a new approach in RP-HPLC. Two chiral derivatizing reagents based on enantiomerically pure (S)-(-)-levofloxacin were synthesized using N-hydroxysuccinimide and N-hydroxybenzotriazole as the activation auxiliaries. Diastereomeric derivatives of the chosen ß-adrenolytics were synthesized under microwave irradiation in a very short reaction time. The (S)-(-)-levofloxacin moiety enhanced molar absorbance of the diastereomeric derivatives resulting in very low limit of detection (1.618 and 4.902 ng/mL, respectively, for diastereomeric derivatives of (RS)-betaxolol and better resolution with lower retention times (for all the analytes), in comparison to literature reports. There was 15-20 times less consumption of mobile phase because of lower retention time.

A highly sensitive resonance Rayleigh scattering and colorimetric assay for the recognition of propranolol in ß-adrenergic blocker.

In this work, a highly sensitive, citrate anion-capped gold nanoparticles (AuNPs)-based assay for the determination of propranolol in real samples with resonance Rayleigh scattering (RRS) and colorimetry was developed. When AuNPs were prepared by the sodium citrate reduction method, citrate anions self-assembled on the surface of AuNPs to form supramolecular complex anions. In BR 4.6 buffer solution, propranolol was positively charged and could bind with AuNPs to form larger aggregates through electrostatic force and hydrophobic effects. This results in remarkable enhancement of the RRS intensity and a color change in the AuNPs solution from red to blue via purple. Thus, a highly sensitive RRS and colorimetric assay the for detection of propranolol was developed with a linear range of 0.2-5.2 and 8-112 ng/ml, respectively. In addition, no difference was seen when comparing R-propranolol with S-propranolol, therefore, this method could not be used in the recognition of chiral propranolol. However, upon addition of other ß-adrenergic blockers, no phenomenon like that seen with propranolol was observed, meaning that this method can be used for determining the presence of propranolol in a mixture ß-adrenergic blockers. Finally, the optimum conditions, factors influencing the reaction, its mechanism and the reasons for enhancement of the RRS were discussed.

Fatal Self-Poisoning With Massive Propranolol Ingestion in a Young Male Physician.

Suicidal intoxication from massive propranolol ingestion is rare. Surprisingly, no reported cases have involved physicians. The author herein reports a case of self-poisoning death due to ingestion of propranolol by a young male physician. A 31-year-old man with major depressive disorder was found dead in his dormitory room. Fifteen empty packages, each having contained ten 40-mg propranolol tablets, were found without any tablets leftover in his room. A suicide note was also found in his room. He was thus alleged to have ingested 6 g of propranolol for self-poisoning. Autopsy findings revealed approximately 150 mL of pink fluid with some partially dissolved pink tablets in the stomach. No anatomic cause of death was found, except for mild dilatation of cerebral ventricles. Toxicologic analysis revealed propranolol in his blood and gastric contents. The cause of death was attributed to acute cardiac arrest due to severe acute propranolol intoxication from self-poisoning caused by major depressive disorder possibly secondary to organic brain syndrome.

Rapid determination of some beta-blockers in complicated matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography.

In this research work, an efficient tandem dispersive liquid-liquid microextraction (TDLLME) procedure coupled with high performance liquid chromatography-ultraviolet detection (HPLC-UV) was successfully applied for the determination of beta-blockers in human plasma and pharmaceutical wastewater samples. High clean-up and preconcentration factor are easily and rapidly feasible via this novel, cheap, and safe microextraction method, leading to high quality experimental data. It consists of two sequential dispersive liquid-liquid microextraction methods, accomplished via air/ultrasonic agitation and air agitation, respectively. In order to enrich the optimal values for the mentioned procedures, the Box-Behnken design (BBD) combined with the desirability function (DF) was used. The optimum values were found to be 11.0 % (w/v) of the salt amount, an initial pH value of 12.0, 103 µL of organic extractant phase, and 45 µL of aqueous extractant phase with pH value of 2.0, resulted in reasonable recovery percentages with a logical desirability. Under optimal experimental conditions, good linear ranges (3-2000 ng mL-1 for metoprolol and 2.5-2500 ng mL-1 for propranolol with the correlation of determinations (R 2s) higher than 0.99) and low limits of detection (0.8 and 1.0 ng mL-1 for propranolol and metoprolol, respectively) were obtainable. Also, TDLLME-HPLC-UV provided good proper repeatabilities (relative standard deviations (RSDs) below 5.7 %, n = 3) and high enrichment factors (EFs) of 75-100. Graphical abstract TDLLME of beta-blockers from complicated matrices.

Simultaneous enantiospecific recognition of several ß-blocker enantiomers using molecularly imprinted polymer-based electrochemical sensor.

The development of a chiral electrochemical sensor using an electrogenerated molecularly imprinted polymer (MIP)-based ultrathin film using R(+)-atenolol (ATNL) as a template was reported. The proposed sensor exhibited distinctive enantiospecific oxidation peaks toward the R-antipodes of four ß-blocker representatives and additional oxidation peaks common to both enantiomers of each studied ß-blocker, allowing thus the simultaneous analysis of all of their enantiomers in a single analysis. The specific preconditioning of the polymer by alternative exposure to aqueous and nonaqueous medium was proven to be essential for the chiral recognition ability of the obtained sensor. The rebinding property of the MIP film was studied by using a well-known redox probe, a change in the morphology and diffusive permeability of the thin polymeric layer in the presence of its template being observed. The applicability of the optimized analytical procedure was demonstrated by the analysis of ATNL's enantiomers in the range of 1.88 × 10(-7)-1.88 × 10(-5) mol/L. The developed polymeric interface is the first reported transductor of a chiral electrochemical sensor able to exhibit simultaneous enantiospecificity toward several ß-blocker representatives extensively used in the pharmaceutical and biomedical fields, offering good prospects in the simple, cost-effective, and fast assessment of their enantiomeric ratio and total concentration.

Direct doping analysis of beta-blocker drugs from urinary samples by on-line molecularly imprinted solid-phase extraction coupled to liquid chromatography/mass spectrometry.

The use of beta-blockers to enhance performance in some sports is forbidden. Based on this regulation, there is a demand for dynamic analytical procedures for analyzing these compounds quickly and without manual sample preparation. Therefore, the use of a molecularly imprinted polymer (MIP) in a multidimensional liquid chromatographic system coupled to a mass spectrometer provides a good alternative for improving the selectivity and practicality of the beta-blocker analyses, as described in this paper. A water-compatible MIP for oxprenolol was synthesized by the precipitation method, using methacrylic acid as a functional monomer and 2-hydroxyethyl methacrylate and glycerol dimethacrylate as hydrophilic monomers. A column filled with MIP was coupled to an LC-MS/MS instrument under the multidimensional configuration, with 10.0 mmol L(-1) ammonium formate buffer (pH 5.0) as the loading and reconditioning mobile phase and a 0.01% formic acid aqueous solution-methanol (30 : 70 v : v) as the elution mobile phase. The system was used for on-line extraction and quantization of oxprenolol (from 1.0 to 75.0 µg L(-1)), atenolol, propranolol, nadolol, pindolol, labetalol and metoprolol (all from 3.0 to 50 µg L(-1)) simultaneously, from urine samples. The correlation coefficient was higher than 0.99 for all the analytes. Suitable precision and accuracy were obtained.

Re-Designing of Existing Pharmaceuticals for Environmental Biodegradability: A Tiered Approach with ß-Blocker Propranolol as an Example.

Worldwide, contamination of aquatic systems with micropollutants, including pharmaceuticals, is one of the challenges for sustainable management of water resources. Although micropollutants are present at low concentrations, many of them raise considerable toxicological concerns, particularly when present as components of complex mixtures. Recent research has shown that this problem cannot be sustainably solved with advanced effluent treatment. Therefore, an alternative that might overcome these environmental problems is the design of new pharmaceutical molecules or the redesign of existing pharmaceutical molecules that present the functionality needed for their application and have improved environmental biodegradability. Such redesigning can be performed by small molecular changes in the drug molecule with intact drug moiety which could incorporate the additional attribute such as biodegradability while retaining its pharmacological potency. This proof of concept study provides an approach for the rational redesign of a given pharmaceutical (Propranolol as an example). New derivatives with small molecular changes as compared to propranolol molecule were generated by a nontargeted photolysis process. Generated derivatives with intact drug moieties (an aromatic ring and a ß-ethanolamine moiety) were further screened for aerobic biodegradability and pharmacological potency. The feasibility of the approach of redesigning an existing pharmaceutical through nontargeted generation of new derivatives with intact drug moiety and through subsequent screening was demonstrated in this study. Application of such approaches in turn might contribute to the protection of water resources in a truly sustainable manner.

Study of enrichment factors for six ß-blockers in aliphatic alcohols by hollow-fiber liquid-phase microextraction.

The selectivity of a suitable organic solvent is key for extraction in liquid-phase microextraction experiments. Nevertheless, the screening process remains a daunting task. Our research aimed to study the relationship between extraction efficiency and extraction solvents, analytes, and finally select the appropriate extraction solvent. In the present article, ß-blockers and six extraction solvents were chosen as the models and hollow-fiber liquid-phase microextraction was conducted. The relationship was built by statistical analysis on the data. Factors affecting extraction efficiency including the logarithms of the octanol/water partition coefficient (logPo/w ) of analytes, acid dissociation constants, the logarithms of the octanol/water partition coefficient of solvents and pH of the sample solution were investigated. The results showed that a low water solubility of extraction solvent is the foundation to ensure higher extraction efficiency. Moreover, when ΔlogPo/w > 0, a higher extraction efficiency is observed at lower ΔlogPo/w , on the contrary, when ΔlogPo/w < 0, extraction efficiency is higher as the absolute value of ΔlogPo/w becomes greater. Finally, the relationship between enrichment factor and extraction solvents, analytes was established and a helpful guidance was provided for the selection of an optimal solvent to obtain the best extraction efficiency by liquid-phase microextraction.

Recent developments in chiral analysis of ß-blocker drugs by capillary electromigration techniques.

The latest developments in chiral analysis of ß-blocker drugs by capillary electromigration techniques are reviewed in this article. Following the previous review by Aturki et al. [Electrophoresis 2011, 32, 2602-2628], this review includes the papers published during the period from January 2011 to December 2013. During this time, some novel chiral selectors were reported and applied to improve the enantioseparation of ß-blocker drugs and structurally related compounds. These chiral selectors include CDs and their derivatives, macrocyclic antibiotics, tartrate complexs, the monolithic molecularly imprinted polymer, and the polymeric surfactants. In addition, this article summarizes the methodological improvements for enhancing sensitivity in chiral analysis of ß-blockers and structurally related compounds by CE. The involved authors described the use of online sample preconcentration techniques to increase the detection sensitivity in the enantiomeric analysis of a broad range of samples.

Sensitive enantioanalysis of ß-blockers via field-amplified sample injection combined with water removal in microemulsion electrokinetic chromatography.

In this study, an on-line sample preconcentration technique, field-amplified sample injection combined with water removal by electroosmotic flow (EOF) pump, was applied to realize a highly sensitive chiral analysis of ß-blocker enantiomers by MEEKC. The introduction of a water plug in capillary before the electrokinetic injection provided the effective preconcentration of chiral compounds. And then the water was moving out of the column from the injection end under the effect of the EOF, which avoided dilution of the stacked ß-blocker enantiomers concentration suffering from the presence of water in separation buffer. Moreover, the addition of H3 PO4 and methanol in the sample solution greatly improved the enhancement efficiency further. Under optimized conditions, more than 2700-fold enhancement in sensitivity was obtained for each enantiomer of bupranolol (BU), alprenolol (AL), and propranolol (PRO) via electrokinetic injection. LODs were 0.10, 0.10, 0.12, 0.11, 0.02, and 0.02 ng/mL for S-BU, R-BU, S-AL, R-AL, S-PRO, and R-PRO, respectively. Eventually, the proposed method was successfully applied to the determination of BU, AL, and PRO in serum samples with good recoveries ranging from 93.4 to 98.2%.

Determination of levels of current drugs in hospital and urban wastewater.

A rapid, sensitive and highly specific HPLC-MS/MS method with direct on-line preparation was applied for the determination of 20 common pharmaceuticals in hospital and urban wastewater. Median drug concentrations were quite similar in the majority of samples, cerca 1 µg L⁻¹ ranging from 0.06 to 2.67 µg L⁻¹ in both water. Pharmaceutical hospital contribution, below 1 %, was negligible, as compared to the huge amount in the municipal plant flow. Due to only partial elimination in the plant, hundreds of kilograms of harmful waste per year are discharged in the River Seine. Therefore, to reduce potential human and environmental exposure, a topic of major concern, an efficient drug treatment procedure should be used at the municipal plant stage in order to reduce urban wastewater pollution. The HPLC-MS/MS method could be a very useful tool to optimize the pharmaceutical wastewater treatment process.

Comparative analysis of selected beta-blockers.

The suitability and effectiveness of a few spectrophotometric and chromatographic methods (UV, FT-IR, MS, TLC) for differentiating analysis of 6 beta-blockers: acebutolol, alprenolol, atenolol, metoprolol, pindolol and propranolol have been tested.