title: Determination of virginiamycin in combination with chlortetracycline in feeds by anion-exchange chromatography.
abstract: Standard additions experiments for chlortetracycline hydrochloride and virginiamycin at a ratio of 16:1 showed a positive bias for both the plate and turbidimetric methods. The bias was eliminated by anion-exchange chromatography in both the presence and absence of feed components. When chlortetracycline and virginiamycin pre-mixes were used for fortification of laboratory-prepared feeds at chlortetracycline to virginiamycin ratios of 8 or 16:1, the recovery of virginiamycin, without treatment, was 93-100% using the plate assay and 181-236% with the turbidimetric method. The corresponding values obtained using anion-exchange chromatography were 89-99 and 85-91%, respectively. The anion-exchange technique is necessary if the turbidimetric method is used for the assay.
authors.forename: H S
authors.initials: HS
authors.lastname: Ragheb
authors.forename: S
authors.initials: S
authors.lastname: Ridge
authors.forename: A
authors.initials: A
authors.lastname: Din
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D002751:Chlortetracycline / Q000032:analysis*; D002852:Chromatography, Ion Exchange; D014769:Virginiamycin / Q000032:analysis*
chemical_list: D014769:Virginiamycin; D002751:Chlortetracycline