Spectrophotometric Determination Of Glucose Research Articles

Spectrophotometric determination of glucose in human serum samples using para‐phenylenediamine and alpha‐naphthol as a chromogenic reagent

AbstractThe global surge in chronic hyperglycemia, the autoimmune disease resulting from diabetes mellitus, has attracted worldwide scientists to develop novel methods for assaying blood glucose levels in the human body. In this work, we reported a new sensitive chromogenic reagent‐based single beam spectrophotometric assay of glucose. This method is based on the catalytic oxidation of D‐glucose to D‐gluconolactone and H2O2 by glucose oxidase (GOD), later by the oxidative coupling of quinone with imine radical to give purple‐colored quinone‐imine chromogenic species with λmax = 540 nm. The linearity of glucose lies in the range of 57.81–1850.2 and 14.45–925.1 µmol L–1 by rate and fixed time method. The Michaelis–Menten constant attained by the Lineweaver–Burk plot at the optimal concentration of the reagents was 526.31 µM with Vmax of 0.2659 EU min–1 and catalytic constant of 1.3295 min–1. Intra‐ and inter‐day precision ranged between 0.73%–1.4% and 1.76%–2.4%, respectively. The standard addition method for the recovery of glucose fluctuated between 97.78% and 104.35%, registering minimal common interference species present in the blood samples. The results showed a good accuracy level (90%–102%), and the calculated limit of detection (LOD) and limit of quantification (LOQ) were as low as 2.17 and 8.56 µM. The proposed work has a good correlation with the standard enzyme kit method. Hence, the proposed system can be convenient for the determination of glucose in biological samples.

Spectrophotometric Determination of Glucose in Pure Form and in Human Embryos' Culture Medium Using Selective Reagent via Studying Their Reaction product

Spectrophotometric Determination of Glucose in Pure Form and in Human Embryos' Culture Medium Using Selective Reagent via Studying Their Reaction product

Enzymatic, Spectrophotometric Determination of Glucose, Fructose, Sucrose, and Inulin/Oligofructose in Foods

A fast, simple, and accurate method, using only standard laboratory equipment, was developed for the quantification of glucose, fructose, sucrose, and inulin/oligofructose in different food matrixes. Samples were extracted using boiling water and hydrolyzed with sucrase and fructanase. Sugars were determined in the initial extract and in both hydrolysates using an enzymatic, spectrophotometric kit for glucose and fructose determination with hexokinase, glucose-6-phosphate dehydrogenase, and phosphoglucose isomerase. Calculations of sucrose and inulin/oligofructose were based only on fructose measurement. Glucose results of the hydrolysates were not used for inulin/oligofructose calculations because of possible interference. Released glucose by the hydrolysis of maltose or by possible partial hydrolysis of other compounds like maltodextrines, starch, lactose, or maltitol could interfere in the measurement of the sucrase and the fructanase hydrolysates. To validate the method, a wide range of different food matrixes and different amounts of inulin/oligofructose (1-54%) were analyzed. Mean recovery +/- relative standard deviation (RSD) for inulin or oligofructose was 96.0 +/- 5.3%. The RSDr for inulin/oligofructose measured on 35 food samples, analyzed in duplicate, was 5.9%. Accuracy and precision of the method were less for samples with large concentrations of sucrose, maltose, maltodextrines, or starch (ratio to inulin/oligofructose >4 to 1). Precision and accuracy were comparable with those of the ion exchange chromatographic method AOAC 997.08 and the enzymatic, spectrophotometric method AOAC 999.03. In contrast to 999.03, this method allows the accurate quantification of both GFn and Fn forms.

Spectrophotometric determination of glucose in foods by flow injection analysis with an immobilized glucose oxidase reactor

A stopped-flow injection analysis system for the determination of glucose is described, based on the iodometric measurement of hydrogen peroxide generated in a glucose oxidase reactor. The detection of the iodine–starch complex was carried out spectrophotometrically. The calibration curve was linear up to 2 mmol l-1 glucose, with a correlation coefficient, r, of 0.9996. The relative standard deviation was 1.6% (n=5) for 1.0 mmol l-1 glucose. A sample frequency of 25 samples h-1 was achieved. This method was applied to the determination of glucose in fruit products and the results obtained using this method were in good agreement with those of a routine enzymatic method. A high dilution of the sample avoided interference from ascorbic acid. The enzyme reactor was stable for 1 month after 200 measurements with no loss of activity.

Spectrophotometric determination of glucose and fructose in injections using tetracynoethylene reagent

A sensitive spectrophotometric method for the determination of glucose and fructose based on formation and solvent extraction of their osazones and subsequent reaction with tetracynoethylene in chloroform medium is described. The proposed method, which compared favorably with an accepted method, was applied to determine the test compounds in injections.

Studies on the spectrophotometric determination of glucose with picric acid

Studies on the spectrophotometric determination of glucose with picric acid