Liquid chromatography with fluorescence detection of lasalocid sodium in feeds and premixes

Lasalocid sodium is extracted directly from feeds and premixes with the mobile phase solution, an aliquot is chromatographed, and the concentration (peak height) of lasalocid sodium is measured by high pressure liquid chromatography with fluorescence detection. Chromatography and detection are completed in about 7 min. The results agree well with those found by the official AOAC fluorometric method, 42.A08--42.A13. The method offers an alternative to the AOAC method and has the capability of processing almost twice as many samples. The average recovery of 4 levels (0.0008, 0.0040, 0.0080, and 0.0120%) of lasalocid sodium from feeds is 100%. Replicate assays of typical poultry mashes and pellets containing about 0.0080% lasalocid sodium yielded coefficients of variation of 2.68--3.35%.