KineticAssayof /3-Hydroxybutyratein Plasmawitha COBAS-BlO

An enzymic rate method for measuring f3-hydroxybutyrate In plasma by use of f3-hy&oxybutyrate dehydrogenase (EC 1.1.1.30) was adapted to the Roche COBAS-BlO centrif-ugal analyzer. Optimum reagent composition and reaction conditions were determined, to provide increased sensi-tivity and accuracy. Use of magnesium ions increased sensitivity. Comparison of results with those of a manual enzymic endpoint method involving perchioric acid pro-tein-free filtrates of whole blood showed excellent cor-relation (r = 0.996). The method has good within-run and day-to-day precision. Linearity of the standard curve ex-tends to 5000 ftmol of /3-hydroxybutyrate per liter. The assay can be completed in less than 5 mm and requires 15.tL of plasma and minimal reagent volumes. Addftlonal Keyphrases: enzymic methods. use of plasm