Naidong W, Hua S, Roets E, Hoogmartens J
Katholieke Universiteit Leuven, Faculteit Farmaceutische Wetenschappen, Laboratorium voor Farmaceutische Chemie en Analyse van Geneesmiddelen, Belgium.
J Pharm Biomed Anal. 1995 Jun;13(7):905-10. doi: 10.1016/0731-7085(95)01330-n.
A thin-layer chromatography (TLC) method using UV and fluoresecence densitometry is described for the assay and purity control of minocycline (MC). With a mobile phase dichloromethane-methanol-water (57:35:8, v/v/v) and a silica gel thin-layer, previously sprayed with 10% m/v sodium edetate adjusted to pH 9.0, 4-epiminocycline and 7-didemethylminocycline were well separated from MC and from each other, 7-monodemethylminocycline and 6-deoxy-6-demethyltetracycline (6-DODMTC) were not separated from each other and were only partially separated from minocycline. 6-DODMTC was selectively determined by fluorescence densitometry, while quantification of other impurities and the assay of MC were performed by UV densitometry. Results obtained with qualitative TLC were compared with those obtained by a liquid chromatography (LC) method using a poly(styrene-divinylbenzene) copolymer stationary phase. The correlation coefficient for TLC and LC results was > 0.999. For TLC the relative standard deviation for the assay of MC at 1.25 mg ml-1 was < 3.0% (n = 4), while for LC it was < 1.0% (n = 4).
描述了一种使用紫外和荧光密度测定法的薄层色谱（TLC）方法，用于米诺环素（MC）的含量测定和纯度控制。以二氯甲烷-甲醇-水（57:35:8，v/v/v）为流动相，硅胶薄层预先喷有调至pH 9.0的10%（m/v）依地酸钠，4-表氨基环素和7-去二甲基米诺环素与MC以及它们彼此之间均能良好分离，7-单去甲基米诺环素和6-脱氧-6-去甲基四环素（6-DODMTC）彼此未分离且仅与米诺环素部分分离。6-DODMTC通过荧光密度测定法进行选择性测定，而其他杂质的定量和MC的含量测定则通过紫外密度测定法进行。将定性TLC获得的结果与使用聚（苯乙烯-二乙烯基苯）共聚物固定相的液相色谱（LC）方法获得的结果进行比较。TLC和LC结果的相关系数>0.999。对于TLC，1.25 mg ml-1的MC含量测定的相对标准偏差<3.0%（n = 4），而对于LC则<1.0%（n = 4）。
