Enzymatic determination of free carnitine in milk and infant formulas

A simple spectrophotometric assay for free carnitine in milk and supplemented infant formulas has been developed. After acid extraction, carnitine is measured enzymatically through its reaction with carnitine acetyltransferase coupled with acetyl coenzyme A and dithiobenzoate (DTNB). The manually performed method is rapid, accurate, and convenient for routine quality-control analysis of infant formulas. The chemistry is also suitable for automation, for greatly enhanced throughput.