Microbore hplc determination of polyether antibiotics using postcolumn derivatization with Benzaldehyde reagents

Monensin, narasin, and salinomycin have been separated by HPLC on microbore column packed with octadecyl-bonded silica gel and detected via postcolumn color reaction with derivative of benzaldehyde in packed-bed reactor. Various benzaldehyde reagents have been tested in batch and 4-dimethylaminobenzaldehyde (DMABA) and vanillin selected as most promising ones. Requirements and characteristics of postcolumn reaction with the two reagents have been investigated and optimized and DMABA has been shown as superior over currently used vanillin reagent. The applicability of postcolumn derivatization with DMABA has been demonstrated by monensin assay in premixes and feeds.