Identification, Isolation, and Characterization of a New Degradation Impurity in Nafcillin Sodium.

A new degradant of Nafcillin Sodium was found at a level of 1.8% w/w during the gradient reversed-phase HPLC analysis in stability storage samples. This impurity was identified by LC-MS and was characterized by (1)H-NMR, (13)C-NMR, LC/MS/MS, elemental analysis, and IR techniques.

A Facile, Improved Synthesis of Sildenafil and Its Analogues.

This paper describes the facile synthesis of sildenafil citrate () and its related compounds through an improved chlorosulfonation reaction using chlorosulfonic acid and thionyl chloride. This synthesis results in pure sildenafil with high yield. The structures of the compounds were determined with infrared (IR), ¹H-NMR and C-NMR spectroscopic methods, and high resolution mass spectroscopy (HRMS) analysis.

Gradient RP-HPLC method for the determination of potential impurities in atazanavir sulfate.

This paper proposes a simple and selective RP-HPLC method for the determination of process impurities and degradation products (degradants) of atazanavir sulfate (ATV) drug substance. Chromatographic separation was achieved on Ascentis(®) Express C8, (150mm×4.6mm, 2.