A method is given for the determination of lasalocid sodium in poultry
feeds and premixes. The lasalocid is extracted from the feed material
into methanol which has been acidified with hydrochloric acid, by agi
tation in an ultrasonic bath at 40 degrees C. The solution is allowed
to stand until the suspended material settles out and a portion is fil
tered through a 0.45 mu m filter. Lasalocid is then determined in the
filtrate by reversed-phase HPLC on a C-18 octadecylsilane column using
a mixture of methanol and a phosphate buffer as mobile phase.