Nelis H J, Vandenbranden J, De Kruif A, Belpaire F, De Leenheer A P
Laboratoria voor Medische Biochemie en voor Klinische Analyse, Ghent, Belgium.
J Pharm Sci. 1992 Dec;81(12):1216-8. doi: 10.1002/jps.2600811218.
A liquid chromatographic method for the determination of oxytetracycline in bovine plasma was developed. Contrary to most current tetracycline assays involving solid-phase extraction, oxytetracycline and the internal standard tetracycline were isolated from buffered plasma by double-phase extraction with ethyl acetate-isopropyl alcohol. The latter component was found to be essential to ensure reproducible partitioning of both tetracyclines into the organic layer. Chromatography was conducted on a Lichrosorb RP8 column, compounds were eluted with 0.01 M oxalic acid-methanol-acetonitrile, and detection was at 357 nm. Linearity was observed over the 0-8.5-micrograms/mL range, and the detection limit approximated 5 ng/mL. The extraction yield was 80.4 +/- 3.4% (n = 12), and the coefficients of variation for repetitive within-run and between-run analyses at two concentration levels (0.25 and 2 micrograms/mL) were 1.0-4.3 and 2.4-7.2%, respectively. The method was applied to a pharmacokinetic study of oxytetracycline in three nonlactating cows after a single intramuscular administration of a long-acting preparation.
建立了一种测定牛血浆中土霉素的液相色谱方法。与目前大多数涉及固相萃取的四环素检测方法不同，土霉素和内标四环素通过乙酸乙酯 - 异丙醇双相萃取从缓冲血浆中分离出来。发现后一种成分对于确保两种四环素可重复地分配到有机层中至关重要。在Lichrosorb RP8柱上进行色谱分析，化合物用0.01 M草酸 - 甲醇 - 乙腈洗脱，并在357 nm处检测。在0 - 8.5微克/毫升范围内观察到线性，检测限约为5纳克/毫升。提取率为80.4±3.4%（n = 12），在两个浓度水平（0.25和2微克/毫升）下，重复批内和批间分析的变异系数分别为1.0 - 4.3%和2.4 - 7.2%。该方法应用于三只非泌乳奶牛单次肌内注射长效制剂后土霉素的药代动力学研究。
