This year, we developed an analytical method for lasalocid sodium, a polyether antibiotic. In a previous report, we introduced a simultaneous analysis of polyether-based antibiotics using a post-column HPLC method. These compounds are considered difficult to analyze by post-column methods. However, unlike other polyether antibiotics, lasalocid is a compound with native fluorescent that can be readily measured using a fluorescence detector. In this report, we analyzed the results according to the method described in the "Feed Analysis Standards" to obtain excellent results.