A stability-indicating ultra-high-performance liquid chromatography (UHPLC) method with a diode array detector was developed and validated for the determination of cis/trans isomers of perindopril l-arginine in bulk substance and pharmaceutical dosage form. The separation was achieved on a Poroshell 120 Hilic (4.6 × 150 mm, 2.7 µm) column using a mobile phase composed of acetonitrile–0.1 % formic acid (20:80 v/v) at a flow rate of 1 mL min?1. The injection volume was 5.0 µL and the wavelength of detection was controlled at 230 nm. The selectivity of the UHPLC-DAD method was confirmed by determining perindopril l-arginine in the presence of degradation products formed during acid–base hydrolysis and oxidation as well as degradation in the solid state, at an increased relative air humidity and in dry air. The method’s linearity was investigated in the ranges 0.40–1.40 µg mL?1 for isomer I and 0.40–2.40 µg mL?1 for isomer II of perindopril l-arginine. The UHPLC-DAD method met the precision and accuracy criteria for the determination of the isomers of perindopril l-arginine. The limits of detection and quantitation were 0.1503 and 0.4555 µg mL?1 for isomer I and 0.0356 and 0.1078 µg mL?1 for isomer II, respectively. 相似文献
Stability-indicating LC methods were developed and validated for the quantitative determination of doripenem, meropenem and tebipenem in the presence of their degradation products formed during forced degradation studies. Isocratic HPLC and UHPLC separations were performed with a core–shell Kinetex 1.7, 2.6 and 5 µm, all C18, 100A, 100 × 2.1 mm columns and the mobile phase composed of acetonitrile and 12 mmol L−1 ammonium acetate in different ratios. The flow rates of the mobile phase were: 0.5 mL min−1 for 1.7 µm column, and 1.0 mL min−1 for 2.6 and 5 µm ones. Detection wavelength was 298 nm and temperature was set at 30 °C. All analysed drugs were exposed to stress conditions which caused their hydrolysis and thermal degradation. The methods were validated by evaluation of linearity, accuracy, precision, selectivity and robustness. Proposed methods were successfully applied for the determination of investigated antibiotics during kinetic studies in aqueous solutions and in the solid state. The advantages of chromatographic procedures which are based on the use of C18 stationary phases with different particle sizes in the analysis of selected carbapenems were discussed.
We describe a study of the influence of a dose rate, i.e. light intensity or photon flux, on the efficiency of induction of a loss of integrity of plasma membranes of live cells in culture. The influence of a photon flux on the size of the light dose, which was capable of causing lethal effects, was measured in an experimental system where singlet oxygen was generated exclusively outside of live cells by ruthenium(II) phenantroline complex. Instantaneous, sensitive detection of a loss of integrity of a plasma membrane was achieved by fluorescence confocal imaging of the entry of this complex into a cell interior. We demonstrate that the size of the lethal dose of light is directly proportional to the intensity of the exciting light. Thus, the probability of a photon of the exciting light inflicting photosensitized damage on plasma membranes diminishes with increasing density of the incident photons. 相似文献
PMB ethers of alcohols are obtained in good yields and under mild conditions using the 4-methoxybenzyl N-allyl thiocarbamate and N-bromosuccinimide (NBS)/TfOH as the catalyst. The present method is very fast, simple, and efficient. 相似文献
We present the synthesis of β-hydroxy sulfonamides derived from d-glucosamine and their application as ligands in titanium tetraisopropoxide promoted enantioselective addition of phenylacetylene to benzaldehyde and selected aromatic and aliphatic aldehydes. The N-3,5-bis(trifluoromethyl)benzenesulfonamido-d-glucosamine derivative was chosen as the most efficient ligand for this addition. The reaction is highly enantioselective for several aromatic aldehydes and enantiomeric excesses up to 92% were obtained. 相似文献
There has been growing interest in simulating biological processes under in vivo conditions due to recent advances in experimental techniques dedicated to study single particle behavior in crowded environments. We have developed a software package, BD_BOX, for multiscale Brownian dynamics simulations. BD_BOX can simulate either single molecules or multicomponent systems of diverse, interacting molecular species using flexible, coarse-grained bead models. BD_BOX is written in C and employs modern computer architectures and technologies; these include MPI for distributed-memory architectures, OpenMP for shared-memory platforms, NVIDIA CUDA framework for GPGPU, and SSE vectorization for CPU. 相似文献
A novel platinum(IV) coordination compound with 6-mercaptopurine (6-Hmp) has been synthesised and characterised by IR and
NMR spectroscopy. Spectroscopic parameters indicate the presence of two chelate (S-6, N-7) monodeprotonated ligands and two
chloride ions in the coordination sphere of [PtCl2(6-mp)2] · H2O (I). Two Pt(IV) coordination compounds, [PtCl2(6-mp)2] · H2O (I) and [PtCl4(dbtp)2] (II), were used in the in vivo test against B16 mouse melanoma tumours. Cytotoxic activity of compound II against the tumour cells was found to be high (LC10 = 2.6 μM, LC50 = 17.0 μM, LC90 = 58.0 μM) compared to that of cisplatin. 相似文献
Adsorption of fibrinogen, modeled as a linear chain of touching beads of various sizes, was theoretically studied using the random sequential adsorption (RSA) model. The adsorption process was assumed to consist of two steps: (i) formation of an irreversibly bound fibrinogen monolayer under the side-on orientation, which is independent of the bulk protein concentration and (ii) formation of the reversibly bound, end-on monolayer, whose coverage was dependent on the bulk concentration. Calculation based on the RSA model showed that the maximum surface concentration of the end-on (reversible) monolayer equals N(⊥∞) = 6.13 × 10(3) μm(-2) which is much larger than the previously found value for the side-on (irreversible) monolayer, equal to N(∞) = 2.27 × 10(3) μm(-2). Hence, the maximum surface concentration of fibrinogen in both orientations is determined to be 8.40 × 10(3) μm(-2) corresponding to the protein coverage of 5.70 mg m(-2) assuming 20% hydration. Additionally, the surface blocking function (ASF) was determined for the end-on fibrinogen adsorption, approximated for the entire range of coverage by the interpolating polynomial. For the coverage approaching the jamming limit, the surface blocking function (ASF) was shown to vanish proportionally to (θ(⊥∞) - θ(⊥))(2). These calculation allowed one to theoretically predict adsorption isotherms for the end-on regime of fibrinogen and adsorption kinetics under various transport conditions (diffusion and convection). Using these theoretical results, a quantitative interpretation of experimental data obtained by TIRF and ellipsometry was successfully performed. The equilibrium adsorption constant for the end-on adsorption regime was found to be 8.04 × 10(-3) m. On the basis of this value, the depth of the adsorption energy minimum, equal to -17.4 kT, was predicted, which corresponds to ΔG = -41.8 kJ mol(-1). This is in accordance with adsorption energy derived as the sum of the van der Waals and electrostatic interactions. Besides having significance for predicting fibrinogen adsorption, theoretical results derived in this work also have implications for basic science providing information on mechanisms of anisotropic protein molecule adsorption on heterogeneous surfaces. 相似文献