ENZYMATIC FLOW-INJECTION DETERMINATION OF FREE L-CARNITINE IN INFANT FORMULAS

Infant formula samples mere analysed to determine their free L-carniti ne content by using flow injection (FI) with an incorporated immobilis ed carnitine acetyltransferase bioreactor. The methodology was based o n the spectrophotometric determination through its reaction with carni tine acetyltransferase coupled with acetyl coenzyme A (acetyl-CoA) and dithiobenzoate. The merging zones technique was used to minimise acet yl CoA consumption. Linearity was observed over the concentration rang e 10-80 mg l(-1) with L-carnitine as standard (r = 0.9998) and the rat e of analysis was 50 h(-1) infant formula samples. The enzymic FI meth od afforded a low RSD (2.2%). Comparisons were made with other methods of known accuracy. The enzymic reactors were stable for 3 months when used daily at the optimum pH.