I N T RO DU C T IO N A company that manufactures drug product or drug substance has a vested interest in determining the impurities associated with their compounds. The analysis of impurities can be a very labor-intensive task involving method development, impurity synthesis, isolation techniques, and various analytical approaches to determine the unambiguous identification of the impurity of i...

This study details the isolation, identification, and characterization of ambroxol's unknown impurity. One unknown impurity of ambroxol was formed in the formulated drug under stress conditions [40°C /75% relative humidity (RH) for 6 months] with the relative retention time (RRT) 0.68 in RP-HPLC. The impurity was enriched by exposing it to heat and it was isolated by using preparative HPLC. The...

Although in vitro transport/inhibition studies are commonly performed on impure drug candidates to screen for pharmacokinetic properties in early development, quantitative guidelines concerning acceptable impurity levels are lacking. The broad goal was to derive models for the effect of impurity on transport and inhibition studies and identify the maximum allowable impurity level that does not ...

An impurity of Ampicillin sodium formed during a gradient reverse phase high performance liquid chromatography (HPLC) analysis of stress stability samples of the drug substance Ampicillin sodium, and the level of this impurity was found at up to 0.9%. This impurity was identified by LC-MS and characterized by (1H NMR, LC/MS/MS, elemental analysis). Based on the spectral data, the impurity was n...

A magnetic impurity in a fermionic superfluid hosts bound quasiparticle states known as Yu-Shiba-Rusinov states. We argue here that, if the impurity is mobile (i.e., has a finite mass), the impurity and its bound Yu-Shiba-Rusinov quasiparticle move together as a midgap molecule, which has an unusual "Mexican-hat" dispersion that is tunable via the fermion density. We map out the impurity disper...

We investigate velocity statistics of an impurity immersed in a uniform granular fluid. We consider the cooling phase, and obtain scaling solutions of the inelastic Maxwell model analytically. First, we analyze identical fluid-fluid and fluid-impurity collision rates. We show that light impurities have similar velocity statistics as the fluid background, although their temperature is generally ...

Magnetic impurities in diamond influence the relaxation properties and thus limit sensitivity of magnetic, electric, strain, temperature sensors based on nitrogen-vacancy color centers. Diamond samples may exhibit significant spatial variations impurity concentrations hindering quantitative analysis pathways. Here, we present a local measurement technique which can be used to determine concentr...

Impurity profiling is a highly intelligent, tedious and expensive task in standardizing the drug products for marketing Authorization. This task usually more complex when the proper impurity standards are not available and synthesis of the same require extra ordinary high cost and time. It has been observed that many a time application for ANDA/DMF/CEP is delayed due to extra ordinary delay in ...

Impurity transport driven by electrostatic turbulence is analyzed in weaklycollisional tokamak plasmas using a semi-analytical model based on a boundary-layer solution of the gyrokinetic equation. Analytical expressions for the perturbed density responses are derived and used to determine the stability boundaries and the quasilinear particle fluxes. For moderate impurity charge number Z, the st...