Rapid method for determination of 2-hydroxy-4-(methylthio)butanoic acid in poultry feeds by capillary...

Capillary isotachophoresis, which involves the separation of charged species under an electric field, has been applied to the rapid determination of 2-hydroxy-4-(methylthio)butanoic acid at 0.04-0.50% concentration levels in corn/soy-based poultry feeds, using conductivity detection. The procedure merely involves a 15 min cold water extraction of the sample and a 15 min analysis after injection of the filtrate into the instrument. Since only charged species migrate and non-ionic species stay virtually at the front of the column, extraordinary selectivity can be achieved. The isotachophoresis method is an order of magnitude faster than the gas chromatographic method reported recently and also provides information on HMB-monomer/dimer ratio in the same run. The sample recoveries exceeded 90% in all concentration ranges studied with coefficients of variation less than +/- 10%.