Simultaneous analysis of carcinogenic N-nitrosamine impurities in metformin tablets using on-line in-tube solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry.

Contamination of active pharmaceutical ingredients (APIs) and pharmaceutical preparations with carcinogenic N-nitrosamines has led to recalls of these products and supply shortages to patients. The present study describes the development of a highly sensitive method for simultaneous analysis of seven N-nitrosamines using on-line in-tube solid-phase microextraction (IT-SPME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine their actual contamination in metformin tablets. Using a Carboxen 1006 PLOT capillary as the extraction device for IT-SPME, these compounds were efficiently extracted and concentrated 6‒24-fold by subjecting 40 µL of sample to 25 repeated draw/eject cycles at a rate of 0.

Photophysical and magnetic properties of magnetic silica gel-supported silicon phthalocyanine complexes.

Enhanced S(1)--> T(1) intersystem crossing of silicon phthalocyanine (SiPc) owing to iron oxide nanoparticles and intense MCD signal of diamagnetic SiPc have been experimentally shown by using SiPcs supported on magnetic silica gel, in which the iron oxide nanoparticles were effectively dispersed.