A simplified resin treatment for removal from urine of substances which inhibit the glucose oxidase peroxidase system of analysis of glucose is described. The original technic designed for AutoAnalyzer use has been modified for a manual procedure. The cost of enzyme reagents and resin has been minimized by use of micro proportions.
The enzymatic principle for determination of glucose in blood, serum and plasma is well established. Application of the glucose oxidase procedure to urine has been more limited, mainly due to the necessity of removing inhibitory substances from urine. Removal of these substances by adsorption, using a mixture of activated charcoal and Lloyd's reagent (hydrated aluminum silicate), has been found more satisfactory than the use of either component singly. The ingredients must be carefully adjusted because it is known that charcoal itself adsorbs glucose. Treatment of urine with resin has been described by Salomon and Johnson, and has been simplified for use with the enzymatic procedure on the AutoAnalyzer in our laboratory. Although automated procedures are becoming more widespread in use, there is still, and undoubtedly always will be, a need for simplified manual methods. Consequently the technic for the removal of inhibitory substances by means of a mixed bed resin has been investigated for adaptation to a manual glucose oxidase method. In this investigation we have found that the proportion of specimen to enzyme reagent may be adjusted so that ultramicro quantities of specimen may be assayed efficiently and conveniently. Precalibrated capillary tubes, 20 lambda volume, were extremely convenient to use and gave reproducible results. An economical amount of enzyme reagent (1 ml.) gave satisfactory photometric sensitivity. This simplification of the enzymatic procedure should help to make more practicable a method specific for urinary glucose.