High-performance liquid chromatographic procedures for the quantitative analysis of 15 tetracycline derivatives in small blood samples.

Published high-performance liquid chromatographic (HPLC) methods for the determination of tetracyclines are modified to determine low levels of each of 15 tetracycline derivatives in small blood samples. The rapid and accurate methods are applicable to pharmacokinetic studies in small experimental animals. The chromatographic procedures allow run times ranging from 2.1-7.3 min using different reversed-phase materials as supports and eluents based on acetonitrile or isopropanol-diethanolamine-EDTA. Detection limits are estimated at 10-500 ng/mL according to the derivative analyzed. The extraction from plasma is based on acidic precipitation of the plasma proteins using trifluoroacetic acid (TFA). The recovery of 13 derivatives from spiked plasma samples (100 micrograms/mL) reached 85-94% (n = 5). The precision data, expressed as coefficient of variation, ranged between 2.1 to 9.1% within run (n = 10) and 4.3 to 11.0% between day (n = 8) respectively.