Stability indicating chromatography conditions

Khalfi, F., Dine, T., Gressier, B., Luyckx, M., Brunet, C., Ballester, L., Goudaliez, F., Cazin, M., and Cazin, J.C. (1996) Comparability and stability of vancomycin hydrochloride with PVC infusion material in various conditions using stability-indicating high-performance liquid chromatography assay, Int. J. Pharm., 139, 243-247. 

The pyrroline-iV-oxide 411 lost enantiomeric purity in the deprotection step. The THP protecting group could be deprotected under very mild conditions using Amberlyst 15 in methanol. However, the mixture was obtained in low yield accompanied by partial or total racemization as indicated by variation of specific rotation. Racemization also occurred during purification by silica gel chromatography or recrystallization. The lack of configurational stability of the nitrone 411 may be explained with the occurrence of a fast (not detectable by NMR), nitrone-hydroxyenamine tautomerism (Scheme 91). 

The most common methods coupled with the three mentioned tests are those also used for evaluating thermal and thermo-oxidative stability, namely measurement of the oxidation induction period by the oxygen uptake test, manometry, DTA, DSC, TG, EGA and EGD in isothermal and nonisothermal (dynamic) conditions oven aging in static or circulating air at 50-150°C, chromatography UV, IR, ESR, NMR spectroscopy, chemiluminescence, viscosimetry, mechanical indices determination, etc. Other criteria refer to discoloration, embrittlement, cracking, loss of elongation, etc. Hydroperoxides concentration can... 

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