Determination of β-blockers in pharmaceutical preparations and human urine by high-performance liquid chromatography with tris(2,2′-bipyridyl)ruthenium(II) electrogenerated chemiluminescence detection

A Novel Composite Voltammetric Sensor Based on Yttria-Stabilized Zirconia Doped with Neodymium-Carbon Black-Nafion Glassy Carbon Electrode for Metoprolol Determination

For the first time, a new composite voltammetric sensor based on yttria-stabilized zirconia doped with neodymium-carbon black-Nafion glassy carbon electrode (YSZNd-CB-Nafion/GCE) for the determination of metoprolol (MET) has been developed. The instrumental parameters and supporting electrolyte were optimized. For 105 s accumulation time, linearity was achieved in the range of 0.01 to 0.2 µM. The limit of detection (for 105 s accumulation time) was equal to 2.9 nM (2 µg/L), and was the best result in comparison to other voltametric sensors. The reproducibility of the metoprolol signal presented as relative standard deviation (RSD) was equal to 1.9% (n = 7). Additionally, our electrode is characterized by high stability, is easy to use, and has a short preparation time. The proposed sensor was found useful for MET determination in plasma and urine, as well as for pharmaceutical samples, with a good recovery parameter (96-108%). Flow injection analysis (FIA) with amperometric detection was also performed for MET determination. The recovery was calculated and was in the range 101-103%, suggesting that the proposed material may be applied in flow injection analysis.

Tris(2,2'-bipyridyl)ruthenium (II) complex as a universal reagent for the fabrication of heterogeneous electrochemiluminescence platforms and its recent analytical applications

In recent years, electrochemiluminescence (ECL) has received enormous attention and has emerged as one of the most successful tools in the field of analytical science. Compared with homogeneous ECL, the heterogeneous (or solid-state) ECL has enhanced the rate of the electron transfer kinetics and offers rapid response time, which is highly beneficial in point-of-care and clinical applications. In ECL, the luminophore is the key element, which dictates the overall performance of the ECL-based sensors in various analytical applications. Tris(2,2'-bipyridyl)ruthenium (II) complex, Ru(bpy)32+, is a coordination compound, which is the gold-standard luminophore in ECL. It has played a key role in translating ECL from a "laboratory curiosity" to a commercial analytical instrument for diagnosis. The aim of the present review is to provide the principles of ECL and classical reaction mechanisms-particularly involving the heterogeneous Ru(bpy)32+/co-reactant ECL systems, as well as the fabrication methods and its importance over solution-phase Ru(bpy)32+ ECL. Then, we discussed the emerging technology in solid-state Ru(bpy)32+ ECL-sensing platforms and their recent potential analytical applications such as in immunoassay sensors, DNA sensors, aptasensors, bio-imaging, latent fingerprint detection, point-of-care testing, and detection of non-biomolecules. Finally, we also briefly cover the recent advances in solid-state Ru(bpy)32+ ECL coupled with the hyphenated techniques.

Disposable electrochemiluminescent biosensor using bidentate-chelated CdTe quantum dots as emitters for sensitive detection of glucose

A novel disposable solid-state electrochemiluminescent (ECL) biosensor was fabricated by immobilizing glucose oxidase and surface-unpassivated CdTe quantum dots (QDs) on a screen-printed carbon electrode (SPCE). The surface morphology of the biosensor was characterized with scanning electron microscopy and atomic force microscopy. With dissolved O(2) as an endogenous coreactant, QDs/SPCE showed strong ECL emission in pH 9.0 HCl-Tris buffer solution with low ECL peak potential at -0.89 V. The ECL intensity was twice that with hydrogen peroxide as coreactant at the same concentration. This phenomenon meant the ECL decreased upon consumption of dissolved O(2) and thus could be applied to the construction of oxidase-based ECL biosensors. With glucose oxidase as a model enzyme, the biosensor showed rapid response to glucose with a linear range of 0.8 to 100 μM and a detection limit of 0.3 μM. Further detection of glucose contained in human serum samples showed acceptable sensitivity and selectivity. This work provided a promising application of QDs in ECL-based disposable biosensors.

Quantitative Analysis of β-Blockers inPharmaceutical Preparations by Capillary Electrophoresis

A simple capillary electrophoresis method was developed for the analysis of four beta-blockers (atenolol, metoprolol, pindolol, and propranolol) in pharmaceutical preparations. The method was validated regarding accuracy, precision, linearity, and detection/quantification limits, and the obtained values were in accordance to those reported in the literature. The method was applied to the determination of the drugs in commercial tablet preparations and proved to be fast and reliable for the quantitative analysis of the beta-blockers.

Determination of Atenolol and Metoprolol by Capillary Electrophoresis with Tris(2,2'-bipyridyl)ruthenium(II) Electrochemiluminescence Detection

Capillary electrophoresis (CE) coupling with a tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)) electrochemiluminescence (ECL) detection technique was developed for the analysis of two beta-blockers, atenolol (AT) and metoprolol (ME). The parameters that influence the separation and detection, including the buffer pH and concentration, the separation voltage, the detection potential and Ru(bpy)(3)(2+) concentration, were optimized in detail. The calibration curve was linear over a concentration range of two or three orders of magnitude for the two beta-blockers. The detection limits for AT and ME were 0.075 and 0.005 microM (S/N = 3). The relative standard deviations (n = 8) of the ECL intensity and the migration time were 2.65 and 0.22% for AT, 2.82 and 0.34% for ME, respectively. The proposed method was applied to determine AT and ME in spiked urine samples; satisfactory results were obtained.

Determination of metoprolol tartrate in tablets and human urine using flow-injection chemiluminescence method

In this paper, a simple, rapid and sensitive flow-injection chemiluminescence method has been developed for the determination of metoprolol tartrate, which acts as a kind of sensitizer in the chemiluminescence emission from the redox of SO(3)(2-) with Ce(IV) in acidic medium. Under the optimized conditions, the proposed method allows the measurement of metoprolol tartrate over the range of 1.5 x 10(-8) to 7.3 x 10(-6)mol/L with a detection limit of 4.7 x 10(-9)mol/L (3sigma), and the relative standard deviation for 7.3 x 10(-7)mol/L metoprolol tartrate (n=11) is 2.20%. The utility of this method was demonstrated by determining metoprolol tartrate in tablets and human urine sample.

Tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence

This paper critically reviews analytical applications of the chemiluminescence from tris(2,2'-bipyridyl)ruthenium(II) and related compounds published in the open literature between mid-1998 and October 2005. Following the introduction, which summarises the reaction chemistry and reagent generation, the review divides into three major sections that focus on: (i) the techniques that utilise this type of detection chemistry, (ii) the range of analytes that can be determined, and (iii) analogues and derivatives of tris(2,2'-bipyridyl)ruthenium(II).

Validated Kinetic Spectrophotometric Method for the Determination of Metoprolol Tartrate in Pharmaceutical Formulations

A kinetic spectrophotometric method has been described for the determination of metoprolol tartrate in pharmaceutical formulations. The method is based on reaction of the drug with alkaline potassium permanganate at 25+/-1 degrees C. The reaction is followed spectrophotometrically by measuring the change in absorbance at 610 nm as a function of time. The initial rate and fixed time (at 15.0 min) methods are utilized for constructing the calibration graphs to determine the concentration of the drug. Both the calibration graphs are linear in the concentration range of 1.46 x 10(-6)-8.76 x 10(-6) M (10.0-60.0 microg per 10 ml). The calibration data resulted in the linear regression equations of log (rate)=3.634+0.999 log C and A=6.300 x 10(-4)+6.491 x 10(-2) C for initial-rate and fixed time methods, respectively. The limits of quantitation for initial rate and fixed time methods are 0.04 and 0.10 microg ml(-1), respectively. The activation parameters such as E(a), DeltaH(double dagger), DeltaS(double dagger) and DeltaG(double dagger) are also evaluated for the reaction and found to be 90.73 kJ mol(-1), 88.20 kJ mol(-1), 84.54 J K(-1) mol(-1) and 63.01 kJ mol(-1), respectively. The results are validated statistically and through recovery studies. The method has been successfully applied to the determination of metoprolol tartrate in pharmaceutical formulations. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.

Electrogenerated Chemiluminescence from Tris(2,2‘-bipyridyl)ruthenium(II) Immobilized in Titania−Perfluorosulfonated Ionomer Composite Films

Electrochemical behavior and electrogenerated chemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3(2+)) immobilized in sol-gel-derived titania TiO2)-Nafion composite films coated on a glassy carbon electrode have been investigated. The electroactivity of Ru(bpy)3(2+) ion exchanged into the composite films and its ECL behavior were strongly dependent upon the amount of Nafion incorporated into the TiO2-Nafion composite films. The ECL sensor of Ru(bpy)32+ immobilized in a TiO2-Nafion composite with 50% Nafion content showed the maximum ECL intensities for both tripropylamine (TPA) and sodium oxalate in 0.05 M phosphate buffer solution at pH 7. Detection limits were 0.1 microM for TPA and 1.0 microM for oxalate (S/N = 3) with a linear range of 3 orders of magnitude in concentration. The present ECL sensor showed improved ECL sensitivity and long-term stability, as compared to the ECL sensors based on pure Nafion films. The present Ru(bpy)3(2+) ECL sensor based on TiO2-Nafion (50%) composite films was applied as an HPLC detector for the determination of erythromycin in human urine samples. The present Ru(bpy)3(2+) ECL sensor was stable in the mobile phase containing a high content of organic solvent (30%, v/v), in contrast to a pure Nafion-based Ru(bpy)3(2+) ECL sensor. The detection limit for erythromycin was 1.0 microM, with a linear range of 3 orders of magnitude in concentration.