Determination of Glucose and Fructose

Dissolve 11.2g triethanolamine. HCI and 0.2 g MgS04 7H20 in 150 ml of distilled water, adjust to pH 7.6 with approximately 4 ml 5 M NaOH, then make up to 200 ml with distilled water. Bring buffer to 20-25 °C before use. (The buffer is stable for 4 weeks when stored at +4°C). 

Nicotinamade-adenine dinucleotide phosphate solution (NADP). 

Dissolve 50 mg NADP-Na2 in 5 ml of distilled water. (Stable for 4 weeks when stored at +4°C). 

5 ml of hexokinase solution (2mg/ml) with 0.5 ml of glucose-6-phosphodehydrogenase solution (Img/ml). (Stable for 1 year when stored at +4°C) 

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Anon (1985) Determination of glucose and fructose enzymatic No. 55, in International Federation of Fruit Juice Producers (IFU) Handbook of Analytical Methods, Swiss Fruit Juice Union, Zug, Switzerland. 

Simultaneous determination of glucose and fructose after HPLC... 

S. Campuzano, O.A. Loaiza, M. Pedrero, F.J. Manuel de Villena and J.M. Pingarron, An integrated bienzyme glucose oxidase-fructose de-hydrogenase-tetrathiafulvalene-3-mercaptopropionic acid-gold electrode for the simultaneous determination of glucose and fructose, Bioelectrochemistry, 63(1-2) (2004) 199-206. 

J.M.T. Carneiro, A.C.B. Dias, E.A.G. Zagatto, J.L.M. Santos, J.L.F.C. Lima, An improved sampling approach in multi-pumping flow systems applied to the spectrophotometric determination of glucose and fructose in syrups, Anal. Chim. Acta 531 (2005) 279. 

Linares, P., Luque de Castro, M. D., Valcarcel, M., Sequential Determination of Glucose and Fructose in Foods by Flow-Injection Analysis with Immobilized Enzymes , Anal Chim. Acta 202 (1987) 199-205. 

Category III (approved alternative methods) A category III method meets all the criteria specified by the Sub-Committee on Methods of Analysis and is used for monitoring, inspection, and regulatory purposes (e.g., enzymatic determinations of glucose and fructose). 

The OrV compendium describes enzymatic individual methods for the determination of glucose and fructose. These methods are based on the conversion... 

Carbohydrates I04 Enthalpimetric determination of glucose and fructose using a reaction cell fitted with a thermistor... 

A trinitrobenzene sulphonate ion-selective electrode has been used for the kinetic determination of glucose and fructose during the reaction of an excess of these sugars with trinitrobenzenesulphonic acid in alkaline solution at 4S-60°C. ... 

The kinetics of oxidation of D-fructose and D-glucose in aqueous alkaline medium with nine sodium salts of mono- and di-substituted A-chloroarylsulfonamides have been determined. The Hammett reaction constants, p, for the oxidation of glucose and fructose are 0.28 and 0.54, respectively. The results have been explained by a plausible mechanism, and the related rate laws have been deduced.108... 

For a determination of a, plot the absorbance measured for runs A2 and B1 to B5 versus the value of (n + /%)/2, where n[ and n are the numbers of moles of glucose and fructose added to the assay tube in the standardization runs. Since the GFS solution is made... 

This method enables the concentrations of glucose and fructose to be determined separately or the sum of their concentrations to be determined in wines and musts. Phosphorylation of glucose and fructose. 

U.S. 6,649,754 (to Merck) describes a process for making mannitol by hydrogenation of a mixture of glucose and fructose. U.S. 3,632,656 (to Atlas Chemical) describes recovery of mannitol from a mixture with sorbitol by crystallization from aqueous solution. U.S. 4,456,774 (to Union Carbide) describes an adsorptive separation of mannitol from sorbitol. U.S. 6,235,947 (to Takeda Chemical Industries) describes a process for recrystallizing mannitol to improve the crystal morphology and hence make a more compressible product that can be used in making tablets. Estimate the cost of production of Mannitol by the Merck route and determine which separation is most economical. What is the additional cost of making the recrystallized product via the Takeda route ... 

Sucrose is a nonreducing sugar. It can be estimated by acid hydrolysis followed by determination of glucose and/or fructose. It may also be determined in a like manner and with greater specificity following the action of the enzyme saccharase. The methods employed for fructose can be used for sucrose. Raybin s reagent is specific for sucrose, but it is not very sensitive (R2). 

Figure 6 Determination of titratable acid at pH 7 (left) and ratio of glucose and fructose (ri t) by regression analyses. For a test set, the predicted values by regression (y-axis) are compared with the reference values (x-axis).

Bemal et al. (1996) also determined seven monosaccharides present in instant coffee. A C-18 SPE step was again used before analysis to protect the chromatography system. Two of the coffees used in this study were adulterated. This was easily detectable because the levels of glucose and fructose were elevated compared to the... 

Studies on the action of acids on phosphoric esters are important in the determination of structures and for analytical purposes. Measurements of the rate of acid hydrolysis were carried out by Lohmann in studies of glucose and fructose phosphates and by Levene in his investigations on nucleotides. Since then they have been used routinely. 

The elegant enzymatic procedure of Drawert and Kupper (59) permits determination of glucose, fructose, and (when necessary) sucrose. Glucose reacts with adenosintriphosphate (ATP) in the presence of hexokinase (HK) to produce glucose-6-phosphate. 

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