IDENTIFICATION OF RESIDUAL TETRACYCLINES IN HONEY BY TLC FABMS/

In order to reliably identify residual tetracycline antibiotics (TCs), oxytetracycline, tetracycline, chlortetracycline, and doxycycline, in honey, a confirmation method using thin-layer chromatography/mass spe ctrometry (TLC/FABMS) with the following characteristics has been esta blished. Use of thioglycerol as a matrix enabled us to measure the FAB mass spectra of TCs without interfering ions due to the matrix and ho ney. Reversed-phase Cg TLC conditions gave reliable separation with go od reproducibility, and the location of TCs extracted from honey could be readily estimated on the basis of the location of neighboring visu alized spots of TCs. The condensation technique improved the detection limits 50-fold with good reproducibility. The clean-up procedure usin g a combination of C-18 and COOH (weak cation exchange) cartridges pro ved to be effective for the identification of residual TCs by TLC/FABM S. The method can reliably identify TCs fortified at concentrations of 0.1 ppm in honey, and has been successfully applied to the identifica tion of residual chlortetracycline in a commercial honey previously fo und positive by high performance liquid chromatography.