Identification, synthesis and characterization of an unknown process related impurity in eslicarbazepine acetate active pharmaceutical ingredient by LC/ESI–IT/MS, 1H, 13C and 1H–1H COSY NMR

Synthesis, isolation, identification and characterization of new process-related impurity in isoproterenol hydrochloride by HPLC, LC/ESI-MS and NMR

One unknown impurity (Imp-II) during the analysis of laboratory batches of isoproterenol hydrochloride was detected in the level ranging from 0.04% to 0.12% by high performance liquid chromatography with UV detection. The unknown impurity structure was proposed as 4-[2-(propan-2-ylamino)ethyl]benzene-1,2-diol (Imp-II) using the liquid chromatography--mass spectrophotometry (LC--MS) analysis. Im...

Isolation, identification and determination of the major degradation product in alprazolam tablets during their stability assay.

The presence of a degradation product of alprazolam tablets that emerged throughout a short-stability assay has been determined and properly characterized. For this purpose an efficient methodology has been successfully applied, including SPE and HPLC methods for isolation and purification, respectively. LC/MS, MS/MS, 1H NMR, 13C NMR, UV and IR have been employed for structural elucidation conf...

Dioxamycin, a new benz[a]anthraquinone antibiotic.

A new antibiotic, dioxamycin (1) was isolated from the culture broth of the strain MH406-SF1, which was closely related to Streptomyces xantholiticus. This antibiotic was purified by countercurrent chromatography, column chromatography and preparative HPLC. The molecular formula of 1 was determined to be C38H40O15 by HRFAB-MS. The structure was determined by spectral analysis of 2D NMR; 1H-1H C...

Probing pattern and dynamics of disulfide bridges using synthesis and NMR of an ion channel blocker peptide toxin with multiple diselenide bonds† †Electronic supplementary information (ESI) available: Details of synthesis and analytical characterization of the Sec-analog of [N17A/F32T]-AnTx mutant including quadrupole ESI and ESI-TOF MS spectra, overlay of 1H-13C HSQC spectra of the double mutant [N17A/F32T]-AnTx and its Sec-analog, scheme and Bruker code of the 77Se-decoupled 1H-77Se CPMG-HSQMBC pulse sequence and comparison of its performance to the classical HMQC method, 1H, 13C, 15N and 77Se resonance assignment of Sec-[N17A/F32T]-AnTx peptide. See DOI: 10.1039/c5sc03995a Click here for additional data file.

Hirtinone, a Novel cycloartane-type triterpene and other compounds from Trichilia hirta L. (Meliaceae).

One novel triterpene cycloartane-type, named hirtinone (1), six protolimonoids - nilocitin (2), dihydronilocitin B (3), melianone epimers (4) and (5), piscidinol A (6) and melianone lactone (7), one tertranortriterpenoid, hirtin (8), and one sesquiterpene, spathulenol (9), were identified in the fruits of Trichilia hirta. The structures were established by 1D and 2D NMR (1H and 13C-NMR, DEPTQ, ...