SOLID-PHASE DETERMINATION OF GLUCOSE IN WHOLE-BLOOD

A solid-phase determination of glucose in whole blood has been developed that employs an immobilized substrate and aqueous enzymes. A phenol, 3-hydroxyphenylacetic acid, was covalently bonded to micron-size porous glass beads, and the derivatized beads were reacted with the oxidized form of horseradish peroxidase and 4-aminoantipyrine to give a surface-bound, red quinoneimine dye. The surface color was quantitatively determined by diffuse reflectance spectrophotometry. Hydrogen peroxide, which oxidizes the enzyme, was determined with a linear range of 10 to 200 mu M and a standard deviation of +/-10 mu M. Samples containing glucose were treated with glucose oxidase to convert the glucose to hydrogen peroxide. Glucose standards showed a linear range of 50 to 200 mg/dL and a standard deviation of +/-9 mg/dL. Results for control sera were in good agreement with values obtained by the usual aqueous method. After correcting for the blood hematocrit, glucose concentrations found for paired plasma and whole blood samples were in good agreement.