DETERMINATION OF 3-HYDROXYBUTYRATE IN SERUM BY FLOW-INJECTION ANALYSIS USING A CO-IMMOBILIZED 3-HYDROXYBUTYRATE DEHYDROGENASE NADH OXIDASE REACTOR AND A CHEMILUMINOMETER

A flow-injection system with a co-immobilized enzyme reactor is descri bed for the determination of 3-hydroxybutyrate. 3Hydroxybutyrate dehyd rogenase and NADH oxidase were immobilized on aminated poly(vinyl alco hol) beads and packed into a stainless-steel column (5 cm X 4 mm i.d.) . Serum was diluted 10-fold with berate buffer (pH 9.4) and ultrafilte red. Filtrate (20 mu l) was injected into the carrier stream. The hydr ogen peroxide produced was detected chemiluminometrically via a lumino l-hexacyanoferrate(III) reaction. The calibration graph was linear for 2x10(-7) M-5 X 10(-4) M; the detection limit was 8 X 10(-8) M and the sample throughput was 30 h(-1) without carryover.