Multicommutation flow system for spectrophotometric L(+)lactate determination in silage material using an enzymatic reaction

A multicommutated flow system for the spectrophotometric determination of L(+)lactate in silage material employing an enzymatic reaction is proposed. The spectrophotometric method was based on L(+)lactate conversion to pyruvate plus hydrogen peroxide by the lactate oxidase enzyme, followed by reaction with the peroxidase enzyme and condensation between 4-chlorophenol and 4-aminoantipyrine. Crude extract of the zucchini (Cucurbita pepo) was used as a natural source of peroxidase enzyme. To achieve a long reaction time and low reagent consumption, the flow set-up was assembled to implement the multicommutation and monosegmented approaches. Using 0.0071IU of lactate oxidase enzyme allowed sample determination within a concentration range of 10.0-100.0mgl-1 L(+)lactate. Other profitable features such as a relative standard deviation of 2% (n=15) for a typical sample containing 75.0mgl-1 L(+)lactate, an analytical throughput of 16 determinations per hour, and a reagent consumption of 16ng of 4-chlorophenol and 2ng of 4-aminoantipyrine per determination were also achieved.