Determination of atenolol in environmental water samples and pharmaceutical formulations at a graphite-epoxy composite electrode

A bare graphite-epoxy composite was evaluated as an electrode material in the determination of atenolol in natural water samples and pharmaceutical formulations for which the analyte was spiked. Using a DPV procedure, a linear response was observed in the 4.45-84.7 mu mol L-1 range with a LOD = 2.23 mu mol L-1, without need of surface renewal between successive runs, and recoveries between 92.5 and 107.5% for pharmaceutical formulations. The results obtained from the proposed procedure agreed with HPLC results within a 95% confidence level. During the determination of atenolol in water samples, recoveries between 96.1 and 102.6% were found.

Optimization of in situ derivatization SPME by experimental design for GC-MS multi-residue analysis of pharmaceutical drugs in wastewater

This paper presents the development of a procedure, which enables the analysis of nine pharmaceutical drugs in wastewater using gas chromatography-mass spectrometry (GC-MS) associated with solid-phase microextraction (SPME) for the sample preparation. Experimental design was applied to optimize the in situ derivatization and the SPME extraction conditions. Ethyl chloroformate (ECF) was employed as derivatizing agent and polydimethylsiloxane-divinylbenzene (PDMS-DVB) as the SPME fiber coating. A fractional factorial design was used to evaluate the main factors for the in situ derivatization and SPME extraction. Thereafter, a Doehlert matrix design was applied to find out the best experimental conditions. The method presented a linear range from 0.5 to 10 mu g/L, and the intraday and interday precision were lower than 16%. Applicability of the method was verified from real influent and effluent samples of a wastewater treatment plant, as well as from samples of an industry wastewater and a river.

Quantification of terbinafine in pharmaceutical tablets using capillary electrophoresis with contactless conductivity detection and batch injection analysis with amperometric detection

Terbinafine hydrochloride (TerbHCl) is an allylamine derivative with fungicidal action, especially against dermatophytes. Different analytical methods have been reported for quantifying TerbHCl in different samples. These procedures require time-consuming sample preparation or expensive instrumentation. In this paper, electrochemical methods involving capillary electrophoresis with contactless conductivity detection, and amperometry associated with batch injection analysis, are described for the determination of TerbHCl in pharmaceutical products. In the capillary electrophoresis experiments, terbinafine was protonated and analyzed in the cationic form in less than 1 min. A linear range from 1.46 to 36.4 mu g mL(-1) in acetate buffer solution and a detection limit of 0.11 mu g mL(-1) were achieved. In the amperometric studies, terbinafine was oxidized at +0.85 V with high throughput (225 injection h(-1)) and good linear range (10-100 mu mol L-1). It was also possible to determine the antifungal agent using simultaneous conductometric and potentiometric titrations in the presence of 5% ethanol. The electrochemical methods were applied to the quantification of TerbHCl in different tablet samples; the results were comparable with values indicated by the manufacturer and those found using titrimetry according to the Pharmacopoeia. The electrochemical methods are simple, rapid and an appropriate alternative for quantifying this drug in real samples. (C) 2012 Elsevier B.V. All rights reserved.

A simple and precise conductometric method for the determination of losartan in pharmaceutical products

Losartan is an antihypertensive agent that lost its patent protection in 2010, and, consequently, it has been available in generic form. The latter motivated the search for a rapid and precise alternative method. Here, a simple conductometric titration in aqueous medium is described for the losartan analysis in pharmaceutical formulations. The first step of the titration occurs with the protonation of losartan producing a white precipitate and resulting in a slow increase in conductivity. When the protonation stage is complete, a sharp increase in conductivity occurs which was determined to be due to the presence of excess of acid. The titrimetric method was applied to the determination of losartan in pharmaceutical products and the results are comparable with values obtained using a chromatographic method recommended by the United States Pharmacopoeia. The relative standard deviation for successive measurements of a 125 mg L-1 (2.71x10(-4) mol L-1) losartan solution was approximately 2%. Recovery study in tablet samples ranged between 99 and 102.4%. The procedure is fast, simple, and represents an attractive alternative for losartan quantification in routine analysis. In addition, it avoids organic solvents, minimizes the risk of exposure to the operator, and the waste treatment is easier compared to classical chromatographic methods.

A LED Based Photometer for Solid Phase Photometry: Zinc Determination in Pharmaceutical Preparation Employing a Multicommuted Flow Analysis Approach

In this work, a LED (light emitting diode) based photometer for solid phase photometry is described. The photometer was designed to permit direct coupling of a light source (LED) and a photodiode to a flow cell with an optical pathlength of 4 mm. The flow cell was filled with adsorbing solid phase material (C-18), which was used to immobilize the chromogenic reagent 1-(2-thiazolylazo)-2-naphthol (TAN). Aiming to allow accuracy assessment, samples were also analyzed employing ICP OES (inductively coupled plasma optical emission spectrometry) methodology. Applying the paired t-test at the 95% confidence level, no significant difference was observed. Other useful features were also achieved: linear response ranging from 0.05 to 0.85 mg L-1 Zn, limit of detection of 9 mu g L-1 Zn (3 sigma criterion), standard deviation of 1.4% (n = 10), sampling throughput of 36 determinations per h, and a waste generation and reagent consumption of 1.7 mL and of 0.03 mu g per determination, respectively.

Propolis Standardized Extract (EPP-AF (R)), an Innovative Chemically and Biologically Reproducible Pharmaceutical Compound for Treating Wounds

The aim of this study was to develop a formulation, containing the propolis standardized extract (EPP-AF (R)), which can assist in the healing of skin lesions. To achieve this objective the antimicrobial activity and chemical composition of the propolis extract was determined. The final product was subjected to in vitro and in vivo pre-clinical evaluation. The broth macrodi-lution method was used to determine the antimicrobial activity of the extracts and formulations against the microorganisms most commonly found in burns, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. Wistar rats with puncture wounded skin were used to evaluate the wound healing properties of propolis. The results of chemical and biological characterization demonstrated the batch-to-batch reproducibility of the standardized extract which is an unprecedented result. The antimicrobial and wound healing activity of the pharmaceutical studied showed the best results when samples contain 3.6% propolis, suggesting that this is the most promising composition.