A nonlinear elasticity phantom containing spherical inclusions

The strain image contrast of some in vivo breast lesions changes with increasing applied load. This change is attributed to differences in the nonlinear elastic properties of the constituent tissues suggesting some potential to help classify breast diseases by their nonlinear elastic properties. A phantom with inclusions and long-term stability is desired to serve as a test bed for nonlinear elasticity imaging method development, testing, etc. This study reports a phantom designed to investigate nonlinear elastic properties with ultrasound elastographic techniques. The phantom contains four spherical inclusions and was manufactured from a mixture of gelatin, agar and oil. The phantom background and each of the inclusions have distinct Young's modulus and nonlinear mechanical behavior. This phantom was subjected to large deformations (up to 20%) while scanning with ultrasound, and changes in strain image contrast and contrast-to-noise ratio between inclusion and background, as a function of applied deformation, were investigated. The changes in contrast over a large deformation range predicted by the finite element analysis (FEA) were consistent with those experimentally observed. Therefore, the paper reports a procedure for making phantoms with predictable nonlinear behavior, based on independent measurements of the constituent materials, and shows that the resulting strain images (e. g., strain contrast) agree with that predicted with nonlinear FEA.

Development and validation of a simple and sensitive high performance liquid chromatographic method for the simultaneous determination of anastrozole, bicalutamide, tamoxifen, and their synthetic impurities

A simple and sensitive analytical method for simultaneous determination of anastrozole, bicalutamide, and tamoxifen as well as their synthetic impurities, anastrozole pentamethyl, bicalutamide 3-fluoro-isomer, and tamoxifen e-isomer, was developed and validated by using high performance liquid chromatography (HPLC). The separation was achieved on a Symmetry (R) C-8 column (100 x 4.6 mm i.d., 3.5 mu m) at room temperature (+/- 24 degrees C), with a mobile phase consisting of acetonitrile/water containing 0.18% N,N dimethyloctylamine and pH adjusted to 3.0 with orthophosphoric acid (46.5/53.5, v/v) at a flow rate of 1.0 mL min(-1) within 20 min. The detection was made at a wavelength of 270 nm by using ultraviolet (UV) detector. No interference peaks from excipients and relative retention time indicated the specificity of the method. The calibration curve showed correlation coefficients (r) > 0.99 calculated by linear regression and analysis of variance (ANOVA). The limit of detection (LOD) and limit of quantitation (LOQ), respectively, were 2.2 and 6.7 mu g mL(-1) for anastrozole, 2.61 and 8.72 mu g mL(-1) for bicalutamide, 2.0 and 6.7 mu g mL(-1) for tamoxifen, 0.06 and 0.22 mu g mL(-1) for anastrozole pentamethyl, 0.02 and 0.07 mu g mL(-1) for bicalutamide 3-fluoro-isomer, and 0.002 and 0.007 mu g mL(-1) for tamoxifen e-isomer. Intraday and interday relative standard deviations (RSDs) were <2.0% (drugs) and <10% (degradation products) as well as the comparison between two different analysts, which were calculated by f test. (C) 2012 Elsevier B.V. All rights reserved.

DEVELOPMENT AND VALIDATION OF A HPLC METHOD FOR QUANTIFICATION OF URSOLIC ACID IN SOLID DISPERSIONS

DEVELOPMENT AND VALIDATION OF A HPLC METHOD FOR QUANTIFICATION OF URSOLIC ACID IN SOLID DISPERSIONS. Ursolic acid is a natural molecule that presents several pharmacological properties. In this work, an analytical method by RP-HPLC has been developed and validated for quantification of this drug in the solid dispersions, using PEG 6000 and Poloxamer 407 as polymers. The method was specific, linear in the range of 1.0-50.0 mu g mL(-1) (r<0.99), precise (CV < 5% for both inter-and intra-assays), accurate (maximum deviation of +/- 13%), and robust to the parameters evaluated. This method has proved to be simple and useful for ursolic acid determination in solid dispersions, enabling its determination in pharmaceutical dosage form.

DEVELOPMENT AND VALIDATION OF AN ANALYTICAL METHOD FOR QUANTITATION OF THE DRUG BEVACIZUMAB BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

DEVELOPMENT AND VALIDATION OF AN ANALYTICAL METHOD FOR QUANTITATION OF THE DRUG BEVACIZUMAB BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY. In this study, an analytical method was developed and validated for quantitation of the drug bevacizumab (Avastin (R)) by high performance liquid chromatography (HPLC). The HPLC column was a BioSuite 250 (R) HR SEC, 300 x 7.8 mm x 5 mu m (Waters, USA). The mobile phase consisted of phosphate buffered saline (PBS). The results revealed that the method was specific, precise. accurate, robust and linear (r(2) = 0.998) from 5 to 75 mu g mL(-1). Therefore, this method can be used in drug release studies or in quality control ampoules of the drug.

Development and validation of a high-performance liquid chromatography method for quantification of egonol and homoegonol in Styrax species

Styrax camporum Pohl, known in Brazil as estoraque do campo or cuia de brejo, has been used in the treatment of gastrointestinal diseases. The therapeutic action of S. camporum has been attributed to the ethyl acetate fraction, although the chemical composition of this fraction has not yet been analyzed. In this study, a high-performance liquid chromatography photodiode array detection (HPLC-PAD) method for analysis of Brazilian Styrax species has been developed. The compounds egonol (1) and homoegonol (2) were found to be present in all the samples investigated by HPLC. These compounds were isolated by open column chromatography followed by preparative TLC, and were identified by 1H NMR. Compounds 1 and 2 were thus proposed as phytochemical markers for Styrax, owing to their biological properties and presence in other Styrax species. The developed method has been validated and successfully applied for quantification of 1 and 2 in S. camporum dried leaves and crude ethanolic extracts from S. ferrugineus and S. pohlii aerial parts. Copyright (c) 2011 John Wiley & Sons, Ltd.

Development of an enzymeless electroanalytical method for the indirect detection of creatinine in urine samples

The aim of this study is to develop a new enzymeless electroanalytical method for the indirect quantification of creatinine from urine sample. This method is based on the electrochemical monitoring of picrate anion reduction at a glassy carbon electrode in an alkaline medium before and after it has reacted with creatinine (Jaffe's reaction). By using the differential pulse voltammetry technique under the optimum experimental conditions (step potential, amplitude potential, reaction time, and temperature), a linear analytical curve was obtained for concentrations of creatinine ranging from 1 to 80 mu mol L-1, with a detection limit of 380 nmol L-1. This proposed method was used to measure creatinine in human urine without the interference of most common organic species normally present in biological fluids (e.g., uric acid, ascorbic acid, glucose, and phosphocreatinine). The results obtained using urine samples were highly similar to the results obtained using the reference spectrophotometric method (at a 95% confidence level). (C) 2012 Elsevier B.V. All rights reserved.