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Clinical Chemistry, Vol 21, 741-745, Copyright © 1975 by the American Association for Clinical Chemistry
1 Department of Chemistry, The Pennsylvania State University,
152 Davey Laboratory, University Park, Pa. 16802.
Glucose can be determined by phosphorylatlon in the presence of hexokinase (EC 2.7.1.1) by using Mg2+/ (ATP)2- as the phosphorylating agent. A novel instrumental quantitation method is described, direct injection enthalpimetry, whereby the heat of the enzymatically catalyzed reaction was measured. The reaction was allowed to proceed to virtual completion (99.5+%) in an adiabatic Dewar vessel at 25.00 ± 0.01 °C (range). Samples were sequentially injected into a reaction mixture consisting of hexokinase, ATP, Mg2+, and a tris(hydroxymethyl)aminomethane buffer (pH 8). Single analyses required <2 min for 0-3 g/liter samples. The linear dynamic range was 0.3-10 g/liter, with zero intercept and a precision and accuracy of 2%. Electrical calibration in situ obviated the need for chemical standards, and because protein and color do not interfere, no sample pretreatment was necessary before analysis.
Submitted on December 23, 1974
Accepted on March 3, 1975
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