A FIA-enzymatic method for the determination of L(+) lactate: application in parenteral solution analysis

A flow injection system for the determination of L(+)lactate in parenteral solutions was developed. The system is based on the amperometric detection of hydrogen peroxide, produced when lactate is converted to pyruvate by the enzyme lactate oxidase over a platinum electrode. The flow injection manif old contains a dialysis unit to maintain the enzyme in a closed re-circulat ion loop. Determinations are made without the need to pre-treat the sample. Under optimal conditions of pH, temperature and hydrodynamic and geometric variables obtained by means of a L-9(3(4)) Taguchi parameter design, a line ar response was achieved for lactate concentrations within the range 2 to 3 0 mM, working at 37 degreesC. Reproducibility was good (RSD < 5%, n = 20) a t a sampling rate of 25 determinations/hour. The results obtained were in c lose agreement with those of a reference method (European Pharmacopeia).