Assay and purity control of oxytetracycline and doxycycline by thin-layer chromatography--a comparison with liquid chromatography.
A thin-layer chromatographic (TLC) method using densitometry is described for the assay and purity control of oxytetracycline and doxycycline. With a mobile phase of dichloromethane-methanol-water (59:35:6, v/v/v) and a silica gel thin-layer, previously sprayed with 10% sodium edetate solution adjusted to pH 9.0, all the potential impurities of oxytetracycline or doxycycline are well separated from the main components and from each other. Results obtained with TLC are compared with those obtained by previously established liquid chromatography (LC) methods using poly(styrene-divinylbenzene) stationary phases. A good correlation was obtained (r greater than 0.9999). For TLC the relative standard deviation (RSD) for the assay of the main component was less than 2%, for LC the RSD was less than 1%.
Weng Naidong
Katholieke Universiteit Leuven, Instituut voor Farmaceutische Wetenschappen, Belgium.
Geelen
S
S
Roets
E
E
Hoogmartens
J
J
D002853:Chromatography, Liquid; D002855:Chromatography, Thin Layer; D004318:Doxycycline / Q000032:analysis* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D010118:Oxytetracycline / Q000032:analysis* / Q000302:isolation & purification; D012015:Reference Standards; D012997:Solvents
D012997:Solvents; D004318:Doxycycline; D010118:Oxytetracycline