Glucose oxidase method

Drugs can also Interfere with laboratory results by negating certain nonspecific oxidation and reduction reactions essential for the chemical assay. Penicillin, streptomycin and ascorbic acid are known to react with cupric Ion thus, false positive results for glucose may occur If a copper reduction method Is used. If the specific enzymatic glucose-oxidase method Is employed, ascorbic acid can cause a false negative result by preventing the oxidation of a specific chromogen In the reaction. 

Salicylates in moderate to large (anti-inflammatory) doses cause false-negative readings for urine glucose by the glucose oxidase method and false-positive readings by the copper reduction method. 

Glucose was analyzed by the glucose oxidase method (8-10) by using reagents obtained from Sigma. Unknowns were quantified by comparing absorbances at 500 nm with those of standards prepared at the same time. 

Table II (104) shows the results of an experiment to learn the proportion of a-D-glucosyl fluoride that is hydrolyzed vs. that used for saccharide synthesis by the different crystalline a-amylases and by diluted saliva. The substrate was again 0.2 M and the enzymes at one-tenth to one-one hundredth the concentrations of the preceding experiment. These digests were analyzed directly for amounts of fluoride (104, 107) and D-glucose (glucose oxidase method) liberated during 2 hours at 30°C.

The numerical values of the time constants summarized in Table 1 confirm that there is no particular time for significant mutarotation to take place in rapid on-line analyses. If glucose uptake is anomerically specific, as has been shown by Benthin et al. [23], analytical results obtained with a glucose oxidase method must be corrected accordingly. The same holds true for analyses of rapid biological transients and for any spiking method (if the spiking solution happens to be freshly prepared). 

The glucose oxidase method (used in the dipsticks and by many automated analyzers) can show a false positive result in some species (e.g, dog, mouse) with high urinary ascorbate levels or in urine contaminated with hypochlorite (bleach) used as a disinfectant (Finco 1997 Loeb and Quimby 1999). 

Compounds 5 and 7 were tested at SO, 10 and 1 mg/Kg po in genetically diabetic mice glycosuria was determined by an enzymatic glucose oxidase method. Tolbutamide was used as control at a dose of 500 mg/Kg. 

The activity of 5 and 7 was tested in normoglycemic rats at dose of 0.1,1, 10 mg/Kg administered orally 30 min before starting the test. Blood glucose level was monitored every 30 min for 2 hours with an enzymatic glucose oxidase method. 

Lott JA, Turner K. Evaluation of Trinder s glucose oxidase method for measuring glucose in serum and urine. Chn Chem 1975 21 1754-60. 

Glucose oxidase method monitored into microtiter plates initial rates were analyzed by Michaelis-Menten equation 45 °C, 50 mM acetate buffer, pH 4.5, from [65]... 

There are a number of possible inhibitors in the glucose determination. Most of them, however, occur in tlie second enzymatic reaction. The glucose oxidase method would be more specific, then, if the hydrogen peroxide were measured directly without the need for a second enzyme. For example, added iodide ion, in the presence of a molybdenum(VI) catalyst, is rapidly oxidized to iodine. The iodine concentration can be followed amperometrically (Chapter 15). An alternative is to measure the depletion of oxygen amperometrically. 

Fig. 2. Urinary glucose excretion in partially depancreatized rats with or without poly(ADP-ribose) synthetase inhibitor injection. 1, 2, and 3 months after the 90% pancreatectomy, the urine of each rat was collected for 24 h. Urinary glucose levels were measured by the glucose oxidase method. O Control rats nicotinamide-injected rats 3-aminobenzamide-injected rats. Statistical significance of differences between rats treated with and without poly(ADP-ribose) synthetase inhibitors was analyzed using Student s t test. Each point is the mean for five different rats vertical bars show SD when larger than the symbol indicating the mean value., and = p<0.10, p<0.05, and p<0.025 vs control rats. The time after the partial pancreatectomy is shown on the abscissa...

Various techniques Glucose was assayed by glucose oxidase method according to Boehringer Carbohydrate metabolism was examined by means of the iv-tolbutamide test calculation was performed according to Lange and Quick (lO) Protein was determined by the biuret method according to Sols (11) ... 

Glucose oxidase methods. This enzyme catalyzes the rea tion... 

Enzymes can be used to give both qualitative and quantitative determinations, depending on the types of analyses made. Quantitative data can be obtained by the measurement of the increase in reducing values with time of hydrolysis and/or the determination of a specific product, such as glucose, using the glucose oxidase method of analysis (see section 3.5 in Chapter 3). Other specific products can be determined using qualitative and quantitative TLC or HPLC. 

Permeability and Diffusion Studies Tubules of different composition were filled with sterile glucose (40mg/mL) and insulin (40mg/mL) solutions in phospate buffered saline, pH 7.4 (PBS). The tubules were sealed and then incubated with shaking at 37° C in 5 mL of PBS. Aliquots were removed at different time intervals and the concentration of glucose determined colorimetrically by the glucose oxidase method 21) and insulin by the protein dye binding assay 22). 

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