A sensitive fluorescence optosensor for analysing propranolol in pharmaceutical preparations and a test for its control in urine in sport

A new electrochemical sensing platform based on HgS/graphene composite deposited on the glassy carbon electrode for selective and sensitive determination of propranolol

Fabrication of selective, sensitive and reliable sensing platform for detection of propranolol (PRO) is still a great challenge. In this study, a new sensitive and selective electrochemical sensor was fabricated for the electrochemical determination of PRO using HgS/graphene composite. The incorporation of HgS microstructures on graphene sheets was done via a facile one-step method, where the simultaneous reduction of GO and the in-situ generation of HgS happened. Owing to the large surface area, excellent electronic conductivity and more electro-active sites provided by graphene, the HgS/graphene composite exhibited better electrochemical ability through the detection of PRO compared to the bare HgS. The HgS/graphene sensor revealed superb selectivity, good repeatability and superior stability of about 96.0 % of its original response after five weeks. Moreover, the sensor displayed excellent analytical parameters such as linear range of 0.5-50.0 μM with low detection limit of 0.05 μM (S/N = 3) and good sensitivity (0.1851 μA/μM). Furthermore, the constructed sensor was applied for detection of PRO in real and pharmaceutical samples, with good recoveries, ranging from 96.0 to 102.0%. The HgS/graphene composite provided here displayed satisfactory electrochemical features may hold great potential to the improvement of electrochemical sensors and electronic devices.

Photoconjugation of Molecularly Imprinted Polymer Nanoparticles for Surface-Enhanced Raman Detection of Propranolol

We report a simple and versatile method to covalently immobilize molecularly imprinted polymer (MIP) nanoparticles on a Raman active substrate (Klarite) using a disulfide-derivatized perfluorophenylazide (PFPA-disulfide). Gold-coated Klarite was functionalized with PFPA-disulfide via a gold-sulfur bond. Upon light radiation, the available azido groups were converted to highly reactive singlet perfluorophenyl nitrene that undergoes a CH insertion reaction and form covalent bonds with the MIP nanoparticles. The resulting surfaces were characterized using scanning electron microscopy and surface enhanced Raman spectroscopy to study the morphology and template affinity of the surfaces, respectively. The Raman measurements clearly show a dose-responsive signal when propranolol binds to the MIP surface. Because the MIP particles were covalently attached to the Raman active substrate, the sensing surface was stable and could be reused after regeneration in acetic acid solution. The MIP-based Raman sensor was used successfully to detect propranolol in urine samples (7.7 × 10(-4) M). Our results show that the high selectivity of MIPs and the fingerprint Raman identification can be integrated into a compact sensing unit using high-efficiency photoconjugation. Thus, the method proposed is reliable, efficient and fast for fabricating label-free chemical sensors.

Electrogenerated chemiluminescence sensor for the determination of

An electrogenerated chemiluminescence (ECL) sensor for the determination of propranolol hydrochloride was fabricated by employing tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)32+) as an ECL signal producer and graphene as a modified material. The ECL sensor was fabricated by adsorbing Ru(bpy)32+ onto a mixture of graphene and Nafion. The introduction of conductive graphene into Nafion was found to greatly enhance the ECL intensity of Ru(bpy)32+ and the ECL intensity of Ru(bpy)32+ decreased in the presence of propranolol hydrochloride. Based on this phenomenon, a sensitive and stable ECL method was developed for the determination of propranolol hydrochloride by employing a Ru(bpy)32+-graphene-Nafion modified electrode. Under the optimized conditions, the ECL intensity was linear with the concentration of propranolol hydrochloride over a range of 1.0 × 10-10 to 5.0 × 10-9 mol L-1 with a detection limit of 3 × 10-11 mol L-1. The ECL sensor exhibited long-term stability with a relative standard deviation of 4.1% for sixteen continuous determinations of 2.0 × 10-9 mol L-1 propranolol hydrochloride. The developed method has been successfully applied to the determination of propranolol hydrochloride in pharmaceutical samples.

On-line coupling of sequential injection extraction with restricted-access materials and post-column derivatization for sample clean-up and determination of propranolol in human plasma

The presented paper deals with a new methodology for direct determination of propranolol in human plasma. The methodology described is based on sequential injection analysis technique (SIA) coupled with solid phase extraction (SPE) column based on restricted access materials (RAM). Special RAM column containing 30 microm polymeric material-N-vinylacetamide copolymer was integrated into the sequential injection manifold. SIA-RAM system was used for selective retention of propranolol, while the plasma matrix components were eluted with two weak organic solutions to waste. Due to the acid-basic and polarity properties of propranolol molecule and principles of reversed-phase chromatography, it was possible to retain propranolol on the N-vinylacetamide copolymer sorbent (Shodex MSpak PK-2A 30 microm (2 mm x 10 mm)). Centrifuged plasma samples were aspirated into the system and loaded onto the column using acetonitrile-water (5:95, v/v), pH 11.00, adjusted by triethylamine. The analyte was retained on the column while proteins contained in the sample were removed to waste. Interfering endogenous substances complicating detection were washed out by acetonitrile-water (15:85), pH 11.00 in the next step. The extracted analyte was eluted by means of tetrahydrofuran-water (25:75), pH 11.00 to the fluorescence detector (emission filter 385 nm). The whole procedure comprising sample pre-treatment, analyte detection and column reconditioning took about 15 min. The recoveries of propranolol from undiluted plasma were in the range 96.2-97.8% for three concentration levels of analyte. The proposed SIA-RAM method has been applied for direct determination of propranolol in human plasma.

Direct determination of propranolol in urine by spectrofluorimetry with the aid of second order advantage

This work presented an application of the second-order advantage provided by parallel factor analysis (PARAFAC) aiming at direct determination of propranolol, a beta-blocker also used as doping agent, in human urine by spectrofluorimetry. The adopted strategy combined the use of PARAFAC, for extraction of the pure analyte signal, with the standard addition method, for a determination in the presence of an individual matrix effect caused by the quenching action of the proteins present in the urine. The urine samples were previously 100 times diluted. For each sample, four standard additions were performed, in triplicates. A specific PARAFAC model was built for each triplicate of each sample, from three-way arrays formed by 231 emission wavelengths, 8 excitation wavelengths and 5 measurements (sample plus 4 additions). The models were built with three factors and always explained more than 99.87% of the total variance. The obtained loadings were related to PRO and two background interferences. The scores related to PRO were used for a linear regression in the standard addition method. The obtained determinations in the PRO concentration range from 5.0 to 20.0 microg ml(-1) provided recoveries between 91.1 and 108.4%.

Chemiluminescence optosensing implemented with multicommutation: Determination of salicylic acid

In this paper we have coupled, for the first time, chemiluminescent detection with multicommuted optosensing principles. This approach has been implemented with the use of a commercial flow cell of 1mm optical path length filled with an appropriate anionic exchanger gel as chemiluminescence sensing phase. The cell was placed in front of the window of the photosensor module of a home-made luminometer developed in our laboratory and a flat mirror was stuck on the back of the cell. The suitability of using chemiluminescence as detection technique in multicommuted flow-through optosensors has been demonstrated: the determination of salicylic acid by simple oxidation with permanganate on the sensing solid phase was chosen as model reaction. The proposed system allows the determination of salicylic acid in pharmaceuticals, with a sample frequency as high as even 60 samples h(-1) and showing a detection limit of 0.30 microg mL(-1), the linear response range is 1-30 microg mL(-1) and the R.S.D. is 3.1%. Satisfactory results have been obtained when applying the sensor to pharmaceuticals. The accuracy of the proposed methodology has been tested by using a reference method.

Use of fluorescence shift and fluorescence anisotropy to evaluate the re-binding of template to (S)-propranolol imprinted polymers

The binding of (R)- and (S)-propranolol to an (S)-propranolol imprinted polymer in organic and aqueous solutions has been studied using fluorescence. The amount of propranolol that binds can be measured by separating non-bound propranolol from the polymer by centrifugation, and measuring the fluorescence intensity. However, this work demonstrates that other measurements can indicate how much propranolol has bound without the need to separate bound and non-bound analyte. In toluene + 0.5% AcOH, and in aqueous buffer (25 mM citrate pH 6 + 0.5% Triton X100) the fluorescence anisotropy increases as the fraction of analyte bound to the polymer increases. In aqueous buffer, binding to the polymer is also accompanied by a change in the relative intensities of fluorescence at 322 nm and at 352 nm. These non-separation techniques have been used to show that the imprinted polymer binds more (S)-propranolol than a non-imprinted polymer, and at least in organic solvent, shows selectivity for (S)- over (R)-propranolol.

Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

Over 1450 references to original papers, reviews and monographs have herein been collected to document the development of molecular imprinting science and technology from the serendipitous discovery of Polyakov in 1931 to recent attempts to implement and understand the principles underlying the technique and its use in a range of application areas. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by papers dealing with fundamental aspects of molecular imprinting and the development of novel polymer formats. Thereafter, literature describing attempts to apply these polymeric materials to a range of application areas is presented.

High operationally stable sol-gel diglycidyloxycalix[4]arene fiber for solid-phase microextraction of propranolol in human urine

A simple, sensitive, and accurate method for the determination of propranolol in human urine has been developed based on solid-phase microextraction (SPME) followed by GC-flame ionization detection (FID). The sol-gel 5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-diglycidyloxycalix[4]arene/hydroxy-terminated silicone oil (diglycidyloxy-C[4]/OH-TSO) fiber was prepared to accommodate to the harsh extraction conditions. It possesses excellent alkali-proof ability and retains its extraction characteristics intact even after treatment with highly alkaline (4 mol/L) NaOH solution. Direct chemical bonding of the coating to the fiber surface provides it with excellent solvent resistance and the introduction of calixarene enhances its thermal stability. The newly developed sol-gel calixarene coating was effectively used for the extraction of propranolol in human urine. No interference with the determination of propranolol was observed from the urine components. Standard curves were linear in the range 50-5000 microg/L for headspace-SPME (HS-SPME) and 25-25000 microg/L for direct-SPME (Dir-SPME) with correlation coefficients better than 0.9999. The detection limit was 0.275 microg/L for HS-SPME and 0.193 microg/L for Dir-SPME. The method was validated using standard addition methodology and recovery values were between 91.4 and 117% for both the sampling modes with the RSDs less than 6% at different concentration levels in the linear ranges. The results obtained by both the sampling modes were feasible, and no significant differences between them regarding accuracy, precision, and detection limits were seen.

A fluorescence optosensor for analyzing naphazoline in pharmaceutical preparations

We have developed an optical sensor for determining and quantifying naphazoline (NPZ) based on its inherent fluorescence property. We have placed a non-ionic-exchanger solid support (Amberlite XAD-7) in a flow cell in the light path of the excitation beam and the fluorescence signal for NPZ is continuously monitored at lambda(exc/nm)=294/306 nm. The response time for this sensor is acceptably fast, 80s, obtaining a detection limit of 2.6 ng mL(-1) with standard deviations of 2.0% at 125 ng mL(-1). This device has been satisfactorily applied to two commercial formulations and its selectivity has been demonstrated with an interference study. The advantages have been compared with the only published sensor for determining NPZ in pharmaceutical preparations and with other analytical methods in the literature.

Spectrophotometric determination of some beta-blockers in dosage forms based on complex formation with Cu(II) and Co(II)

Four sensitive and accurate spectrophotometric methods have been developed for the assay of Acebutolol Hydrochloride (ACH), Atenolol (ATE) and Propranolol Hydrochloride (PRH), which are based on the complexation of drugs with copper(II) (Cu(II)) and cobalt(II) (Co(II)). The coloured products are measured at 613, 694, 548 and 614 nm for ACH-Co(II), ATE-Cu(II), PRH-Cu(II) and PRH-Co(II) method, respectively. The optimization of various experimental conditions is described. Conformity with Beer's Law was evident over a concentration range in the of 2 x 10(-5) - 1 x 10(-2) mol/L. The molar absorptivity, detection and quantification limits are calculated. The results obtained showed good recoveries of 100.2 +/- 1.1, 100.3 +/- 1.2, 100.75 +/- 1.0 and 99.55 +/- 1.1 % with relative standard deviations of 0.410, 0.490, 0.161 and 0.140 % for ACH-Co(II), ATE-Cu(II), PRH-Cu(II) and PRH-Co(II) method, respectively. They were applied to the analysis of tablet forms of the drugs and the results were statistically compared with those obtained by official and literature methods using t- and F-tests. There were no significant difference among the mean values and precisions of the methods at 95% confidence level.