Ultrasonic assisted SPME coupled with GC and GC-MS using pencil lead as a fiber for monitoring the organic volatile impurities of ceftazidime

A simple, rapid, non-destructive, and in-situ method for the isolation and sampling of organic volatile impurities in Ceftazidime is developed using solid-phase microextraction (SPME). For the monitoring of the extracted compounds, gas chromatography (GC) and GC-mass spectrometry analyses are used. The effective factors such as nature of the fiber, SPME mode, extraction temperature, and ultrasonic assistance have been investigated and detailed here. Qualification studies reveal the existence of pyridine (as a degradation product of ceftazidime) and the residual solvents; acetone, methylene-chloride, and diethylamine are the main impurities in the studied pharmaceutical. External standard method is used for quantitative analysis. The % relative standard deviation values are below 10%, and the limits of detection for the detected solvents are 1.06, 0.98, 0.83, and 0.51 ppm, respectively. The proposed method is both accurate and linear and could be used in quality control of ceftazidime and also its stability investigations.     

Crystal structures and in vitro anticancer studies on new unsymmetrical copper(II) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine: a comparison with related symmetrical ones

Two new unsymmetrical copper(II) Schiff base complexes, [CuLⁿ(py)]ClO₄ (n = 1, 2) in which Lⁿ represents a tridentate N₂O type Schiff base ligand, were synthesized. Lⁿs were derived from monocondensation of meso-1,2-diphenyl-1,2-ethylenediamine with salicylaldehyde or 3-methoxysalicylaldehyde. The reaction between [CuLⁿ(py)]ClO₄ and other salicylaldehyde derivatives resulted in new N₂O₂ unsymmetrical tetradentate Cu^II complexes, CuL^3–6. Crystal structures of [CuL¹(py)]ClO₄, CuL⁴, and CuL⁵ were obtained. These new complexes as well as a series of related symmetrical ones (i.e. CuL^7–12) were tested for their in vitro anticancer activity against human liver cancer cell line (Hep-G2) by MTT and apoptosis assay. All of the complexes showed considerable cytotoxic activity against tumor cell lines (IC₅₀ = 5.13–16.24 μg mL^?1). The symmetrical CuL⁷ was the most potent anticancer derivative (IC₅₀ = 5.13 μg mL^?1) compared to the control drug 5-FU (IC₅₀ = 5.4 μg mL^-1, p < 0.05). Flow cytometry experiments showed that the copper derivatives especially [CuL²(py)]ClO₄ and CuL⁷ induced more apoptosis on Hep-G2 tumor cell lines compared to 5-FU.     

The helical melamine–Keggin hybrid nanorods: syntheses and characterizations with two strategies,one-step solid-state chemical reaction and experimental solvent diffusion method

Two new Melamine-Keggin hybrid nanorods, MELH-PMo₁₂ and MELH-PW₁₂, for the first time are successfully synthesized by two chemical methods, one-step solid-state chemical reaction method and experimental solvent diffusion method at room temperature. One-step solid-state reactions involve grounded nanorod materials along with grinding of row material and with solvent diffusion method these nanorods synthesized in single crystals form. These compounds crystallized in trigonal space groups P-3. Elemental analysis, infrared spectroscopy, UV spectroscopy and XRD analysis results prove that the samples still possess Keggin type structure. Transmittance electron microscopy and single-crystal X-ray have shown that the samples have nanorod structures.     

Line graphs: Their maximum nullities and zero forcing numbers

The maximum nullity over a collection of matrices associated with a graph has been attracting the attention of numerous researchers for at least three decades. Along these lines various zero forcing parameters have been devised and utilized for bounding the maximum nullity. The maximum nullity and zero forcing number, and their positive counterparts, for general families of line graphs associated with graphs possessing a variety of specific properties are analysed. Building upon earlier work, where connections to the minimum rank of line graphs were established, we verify analogous equations in the positive semidefinite cases and coincidences with the corresponding zero forcing numbers. Working beyond the case of trees, we study the zero forcing number of line graphs associated with certain families of unicyclic graphs.     

Synthesis of cobalt-based magnetic nanocrystals from cobalt(II) heterocyclic amine complexes

Research on Chemical Intermediates - Cobalt nanocrystals with different morphologies and magnetic properties were prepared from three cobalt(II) heterocyclic amine precursors in alcoholic solution...     

On the rate of complete convergence for weighted sums of NSD random variables and an application

In this paper, the complete convergence is established for the weighted sums of negatively superadditive-dependent random variables. As an application, the Marcinkiewicz-Zygmund strong law of large numbers for the random weighted average is also achieved, and a simulation study is done for the asymptotic behaviour of random weighting estimator.     

Correct derivation of a combined version of the Jouyban–Acree and van’t Hoff model and some comments on ‘Determination and correlation of the solubility of myricetin in ethanol and water mixtures from 288.15 to 323.15 K’

The experimental data reported in the paper by Cai and co-workers [DOI: 10.1080/00319104.2016.1163560] pertaining to the solubility of myricetin dissolved in binary aqueous–ethanol solvent mixtures has been reanalysed. A correct mathematical derivation is provided for the correlation expression from a combination of the van’t Hoff and Jouyban–Acree models. Cai et al. who used the expression in their study, however, erroneously implied that the expression resulted from a simple transformation of the Jouyban–Acree model. No mention was made that one needed to assume a van’t Hoff-type mathematical representation for how the solute solubility varied with temperature in the two mixture co-solvents.     

The potential of the capillary electrophoresis techniques for quality control of biopharmaceuticals—A review

CE is considered as a powerful technique in biopharmaceutical industry, owing to its inherent advantages such as high resolution, efficient separation, and its flexibility to couple with high‐sensitive detecting methods. Present review provides a summary of the applications of CE‐based methods in the quality control of biopharmaceuticals according to the papers published between 1994 and July 2014. This article is divided into the sections based on different CE modes applied in the analysis of biopharmaceuticals and gives detailed information about the employed experimental conditions. At the end some overall conclusions and perspectives are given.     

Modified equation of state extended to imidazolium-, phosphonium-, pyridinium-, pyrrolidinium- and ammonium-based ionic liquids

An analytical equation of state (EoS) has been previously employed by Hosseini and Sharafi (Ionics 17:511, 2011) for modelling of PVT data of some ionic liquids (ILs). In this work, we have extended the mentioned model to five classes of ILs by the use of alternative scaling constants for corresponding states correlation procedure. For this purpose, ILs involving imidazolium, phosphonium, pyridinium, pyrrolidinium and ammonium cations have been taken into account. From these, 1,294 experimental data points examined to show the reliability of the modified EoS. The comparison of predicted densities with the measured values over a broad range of temperature 293?C452 K and pressures up to 150 MPa led to the encouraging results. The average absolute deviation of calculated densities from literature values was found to be 0.73%. Moreover, to establish the predictive power of proposed model, the reproduced densities have been compared with those obtained by another literature work. Moreover, we have demonstrated the density behaviour of studied ILs in terms of alkyl chain length of imidazolium cation via proposed model.     

Silica Chloride Nano Particle Catalyzed Ring Opening of Epoxides by Aromatic Amines

Silica chloride nano particle (nano SiO₂‐Cl), has been found to be heterogeneous catalyst for facile, simple and mild ring opening of epoxides with aromatic amines to afford β‐amino alcohols in dry CH₂Cl₂ at room temperature.