1. The ability of crystalline ribonuclease to hydrolyze proteins is due to impurities present in the preparations and not to an intrinsic property of the ribonuclease molecule. The amounts of these impurities vary enormously with different preparations. 2. The dangers inherent in the use of crystalline enzymes as specific tools, without assaying them for all possible interfering impurities, are...

Two unknown impurities were detected in the cefazolin sodium bulk drug substance using gradient reversed-phase high-performance liquid chromategraphy (HPLC). These impurities were isolated by preparative HPLC and characterized by using spectroscopic techniques like LC-MS, LC-MS/MS, 1D, 2D NMR, and FT-IR. Based on the spectral data, the impurities have been characterized as N-(2,2-dihydroxyethyl...

A method is proposed to determine trace rare earth impurities in high-purity CeO2 by HPLC combined with electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES). The chromatographic retention behaviours of the matrix (Ce) and rare earth impurities were studied using 2ethylhexyl hydrogen 2-ethylhexylphosphonate (P507) resin as the stationary phase and dil...

We evaluated the influence of impurities in the vacuum chamber used for the fabrication of organic light-emitting diodes on the lifetime of the fabricated devices and found a correlation between lifetime and the device fabrication time. The contact angle of the ITO substrates stored the chamber under vacuum were used to evaluate chamber cleanliness. Liquid chromatography-mass spectrometry was p...

A multiscale quasicontinuum density functional theory method is used to study the solid solution effect on dislocation nucleation during nanoindentation. Specifically, an Al thin film with Mg impurities is considered. We find that the solid solution effect depends sensitively on the local configuration of the impurities. Although a random distribution of the impurities increases the hardness of...

The incorporation of intrinsic point defects into a growing crystal is affected by the presence of impurities that can react with vacancies and self-interstitials. The critical value of the ratio of the growth rate, V , to the axial temperature gradient, G, ~V/G ratio! that separates the interstitial growth mode from the vacancy growth mode, is shifted by impurities, and this effect can be desc...

Two unknown impurities were observed during the process development for multigram-scale synthesis of eplerenone (Inspra®). The new process-related impurities were identified and fully characterized as the corresponding (7β,11α,17α)-11-hydroxy- and (7α,11β,17α)-9,11-dichloroeplerenone derivatives 12a and 13. Seven other known but poorly described in the literature eplerenone impurities, includin...

We describe the BPS dynamics of vortices in the presence of impurities. We argue that a moduli space of solitons survives the addition of both electric and magnetic impurities. However, dynamics on the moduli space is altered. In the case of electric impurities, the metric remains unchanged but the dynamics is accompanied by a connection term, acting as an effective magnetic field over the modu...

A two-dimensional lattice hard-core boson system with a small fraction of bosonic or fermionic impurities is studied. The impurity hopping and interactions are identical to those of the dominant bosons, so that effects due to quantum statistics can be isolated. A quantum Monte Carlo scheme is developed in which bosonic paths are sampled and the impurities are introduced at the level of summing ...

Fluothane (halothane BP), one of the purest anaesthetics, contains traces of some impurities amounting to a total of 005 per cent w/w, none of them exceeding 001 per cent w/w. Once these impurities had been identified they were synthesized and tested for anaesthetic activity and toxicity. The results of these experiments showed that most of these impurities have low toxicity but Fluothane conta...