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NADH electrochemical sensor for the enzymatic determination of L ‐ and D ‐lactate and 3‐hydroxybutyrate using a flow injection analysis
Author(s) -
Marrazza G.,
Cagnini A.,
Mascini M.
Publication year - 1994
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140060308
Subject(s) - chemistry , ionic strength , diaphorase , glutaraldehyde , lactate dehydrogenase , chromatography , analyte , flow injection analysis , electrochemistry , immobilized enzyme , dehydrogenase , buffer solution , electrode , analytical chemistry (journal) , enzyme , detection limit , biochemistry , organic chemistry , aqueous solution
A NADH sensor in the submicromolar range, assembled in a wall‐jet cell using a flow injection analysis (FIA) procedure, was studied and coupled with enzyme reactors. Spectroscopic graphite was used as electrode material without any mediator. The measurements were performed at an applied potential of + 500 mV vs. Ag/AgCD. L ‐, D ‐lactate, and 3‐hydroxybutyrate dehydrogenase were immobilized on aminopropyl‐controlled pore glass beads using glutaraldehyde in a packed‐bed enzyme reactor, L ‐, D ‐lactate, and 3‐hydroxybutyrate were oxidized in the presence of NAD + , and an equivalent amount of NADH was produced and measured. By careful choice of pH, buffer, and NAD + concentration, the analytes could be measured in the range of 1 × 10 −6 to 1 × 10 −4 M in a few seconds. Large blank effects were evidenced with this procedure if the carrier and the sample differed in ionic strength of about 1 × 10 −3 M when the total ionic strength is 0.8 M. Therefore, the use of such a system for reach samples requires further investigation.