The control of impurities is a critical issue in pharmaceutical industry and very strict regulations related with this issue have been introduced by ICH (International Conference on Harmonisation). The drugs impurities in general are classified into two types: (1) impurities associated with the Active Pharmaceutical Ingredients (API) production and, (2) impurities generated during formulation a...

This article deals with the identification and characterization of process-related impurities of trans-resveratrol (3,5,4'-trihydroxystilbene), which exhibits several health benefits, including cancer prevention. During the synthesis of the bulk drug resveratrol, three new impurities were observed. The impurities were detected using the high-performance liquid chromatographic (HPLC) method, who...

In this paper a fast and novel stability-indicating ultra fast LC method for separation and estimation of impurities in clopidogrel and aspirin in their combined tablet dosage form and omeprazole was developed. The separation of USP related substances of clopidogrel (A, B and C), aspirin (D), omeprazole (A, B and C) and few other unknown impurities was detected by using ultra fast liquid chroma...

We investigate the bilinear and biquadratic interlayer exchange coupling in Co/Fe/MgO/Fe(001). Samples are grown through molecular beam epitaxy and the interlayer exchange coupling is measured through magneto-optic Kerr effect along wedge samples. By varying the location of Fe impurities between the interface and middle of the MgO spacer, we find that the couplings are enhanced and are dependen...

The NLSE soliton scattering by impurities is considered in the framework of the one-dimensional model. The scattering intensity is characterized by the reflection coefficient. The reflection coefficient of the soliton is calculated in the Born approximation of the perturbation theory for the following cases: (i) and isolated impurity, (ii) two point impurities, and (iii) a regular or random sys...

Abstract In this paper we will give a short rewiew about the conductance of a mesoscopic waveguide strip with a few impurities. Green-function method is used allowing to treat systems with low number of impurities, not only the completly clean case. Investigating a wire containing Diracdelta potentials (modelling the impurities) we found that increasing number of impurities can cause a transiti...

In the initial scale-up batches of the experimental drug substance AMG 517, a pair of unexpected impurities was observed by HPLC. Analysis of data from initial LC-MS experiments indicated the presence of two dimer-like molecules. One impurity had an additional sulfur atom incorporated into its structure relative to the other impurity. Isolation of the impurities was performed, and further struc...

During the manufacture of bulk drug midazolam various impurities arised that can be the related products or degradation products. Structures of eight impurities that can arise during the manufacture of bulk drug midazolam were proposed. In the present work, synthesis of these impurities and their characterization by different spectroscopic techniques have been done. HPLC method was developed fo...

Attention is given here to the mass spectral data of impurities present in illicit drug preparations of 3,4-(methylenedioxy)amphetamine and 3,4-(methylenedioxy)methylamphetamine. These "designer" drugs, having emphatic properties, were synthesized following well-known procedures such as the reductive amination route, the Leuckart reaction, and the nitropropene and the bromopropane routes. Based...

A physicochemical characterization of the process-related impurities associated with the synthesis of pemetrexed disodium was performed. The possibility of pemetrexed impurities forming has been mentioned in literature, but no study on their structure has been published yet. This paper describes the development of the synthesis methods for these compounds and discusses their structure elucidati...