Multicommutation flow system for spectrophotometric l(+)lactate determination in silage material using an enzymatic reaction Original Research Article

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 0.0071 IU of lactate oxidase enzyme allowed sample determination within a concentration range of 10.0–100.0 mg l−1 l(+)lactate. Other profitable features such as a relative standard deviation of 2% (n=15) for a typical sample containing 75.0 mg l−1 l(+)lactate, an analytical throughput of 16 determinations per hour, and a reagent consumption of 16 ng of 4-chlorophenol and 2 ng of 4-aminoantipyrine per determination were also achieved.