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6605954 
Journal Article 
ASSAY AND PURITY CONTROL OF CHLORTETRACYCLINE AND DEMECLOCYCLINE BY TLC A COMPARISON WITH LC 
Naidong, W; Hauglustaine, C; Roets, E; Hoogmartens, J 
1991 
Yes 
Journal of Planar Chromatography - Modern TLC
ISSN: 0933-4173 
63-68 
A thin layer chromatographic (TLC) method using densitometry is described for the assay and purity control of chlortetracycline and demeclocycline. With a mobile phase of dichloromethane-methanol-water (60 + 35 + 5, v/v) for chlortetracycline and (59 + 35 + 6, v/v) for demeclocycline, and a silica gel layer previously sprayed with 10% sodium EDTA solution adjusted to pH 8.0, all the major impurities of chlortetracycline or demeclocycline were well separated from the main components and from each other. The less important anhydro derivatives of CTC or DMCTC were better separated on silanized silica gel with a mobile phase of methanol-acetonitrile-0.5 M oxalic acid (pH 2.0) (1 + 1 + 6, v/v). TLC results were compared with those obtained by previously established LC methods using a poly(styrene-divinylbenzene) stationary phase. A good correlation was obtained (r > 0.9999). For TLC the relative standard deviation (RSD) for the assay of the main component was < 2%; for LC the RSD was < 1%.