Improved Thin-Layer Chromatographic Identification of Tetracyclines and Their Degradation Products: Application to An Epimerization Study

Tetracycline Degradation Products in Commercially Available Tetracycline-7-3H

“…(6) reported that when 1 and its degradation products were chromatographed on kieselguhr G using Solvent System A, I and IV migrated at nearly the same rates with R, values of 0.53 and 0.47, respectively. In the present study with acid-washed silica gel plates and Solvent System A, I and IV were not resolved into separate radioactive peaks.…”

“…Thin-Layer Plates-Kieselguhr G1 and kieselguhr N2 TLC plates were prepared as described by Gyanchandani d. (6). Acidwashed silica gel3 and silica gel' plates were pretreated by sodking for 1 hr.…”

Separation and Quantitative Determination of Impurities in Tetracycline

“…Van den Bulcke (14) studied the influence of the binder and polyalcohols in the stationary phase and of the solvent systems both on the separation of tetracyclines and the detection of their impurities. Microcrystalline cellulose was used to separate I and other impurities from IV (15)(16)(17)(18).Gyanchandani et al (19) first impregnated the plates with the solvent system, a process that conditioned them so that they could be stored for several weeks. Finally, van Hoeck et al (20) separated I, 11, and I11 from IV on a solvent-impregnated plate and determined IV by direct fluorometry.…”

“…Finally, van Hoeck et al (20) separated I, 11, and I11 from IV on a solvent-impregnated plate and determined IV by direct fluorometry. The methods described in 19, and 20 seem to be the most reliable, although they are subject to important criticism.The use of acid-washed kieselguhr is undesirable (14) because the washing process is lengthy and does not result in reproducible separations. Microcrystalline cellulose is also unsatisfactory because the support, as described by , is difficult to prepare and does not allow a good separation while the use of citrate and/or phosphate buffers may markedly increase the epimerization of the tetracyTable I-TLC of I-V Con c e n -R f x 100 Comtration, pound P!dPl Ia I1 fJ I11 c I 0.025 98 86 95 V 0.025 21 32 72 I1 0.025 1 6 27 30 IV 5.0 1 0 20 50 I11 0.025 4 1 0 28 aWith 10% VI plates.…”

“…bWith 3.7% VI plates used immediately after impregnation. C With 3.7% VI plates used 24 hr after impregnation.clines (19,21,22). For the same reason, the temperature should be controlled during the development (21).…”