Determination of Sulphonamides and Tetracyclines in Animal Feed with AMD

Sulphonamides are administered to animals in the form of feed supplements. Their safe identification and quantification in such supplements is a task for regulatory and surveillance laboratories. Since such feed supplements often contain complex extraneous substances which are extracted simultaneously with the drugs, reliable chromatographic separation from matrix compounds is required as well as secure identification by in-situ spectra comparison.
Samples containing drugs are extracted, then lipids remove3d with n-hexane. The concentrated samples separated by AMD (automated multiple development). The active substances are quantified by multiwavelength scanning, identification is ensured by computer assisted spectra comparison.
The AMD method achieves an improved resolution compared with conventional TLC procedures. For instance, the molecular difference between sulfadimidine and sulfamerazine is only one methyl group. The shallow polarity gradient used in this AMD procedure, allows the safe separation of these substances.