Determination of alanine, lactate, pyruvate, beta-hydroxybutyrate, and acetoacetate by flow injection analysis (FIA)

The flow infection analysis (FIA) described by Ruzicka and Hansen was adjusted for lactic acid determination by Rydevik et al. We were able to elaborate some other NAD or NADH-dependent enzyme reactions with the FIA system. The reliability of the alanine assay corresponds to that of the lactate FIA method. The coefficient of variation was on an average 2.8%; th sample rate was 60/h with consistent duplicates. The beta-OHB assay had almost the same validity. Pyruvate, however, was less reliable with higher coefficients of variation. ACAC FIA assay, which was suitable for the determination in acid solution after neutralization, could not yet be employed for the determination in serum. In comparison to the manual enzyme methods, the FIA assays described here indicated a higher sampling rate, a lower reagent consumption, a lower coefficient of variation, a better reproducibility, and a greater consistency of duplicates.