Sugars ferricyanide methods

The reasons for allowing such high glucose values to persist requires explanation. The blood sugar values were estimated in the routine laboratory on microsamples using the automated ferricyanide method. Unless specimens are diluted, this method becomes inaccurate at sugar values above 250 mg per 100 ml. Specimens giving this result were reported as such and not repeated on diluted samples. Also,... 

A number of important methods are based on the oxidation of sugars by ferricyanide ion in alkaline solution. The method is open to the same objections as the copper reduction methods, namely, the lack of a stoichiometric reaction and the dependence of the method on arbitrarily chosen conditions. The ferricyanide may be used to titrate the sugar solution directly by the use of picric acid or of methylene blue as an indicator. Or, the reduced ferrocyanide may be precipitated as the zinc salt, and the excess ferricyanide determined iodometrically. The Hagedom-Jensen method and the Hanes modification utilize the latter procedure. In the Folin-Malmros micro method, Prussian blue is formed and determined colorimetrically. Extensive application of the ferricyanide method has been made in the determination of the diastatic power of amylase preparations and in blood analysis. 

It is difficult to correlate reducing sugar units based on different analytical methods. Hahn (63) determined the reducing values for enzymic digests of hyaluronic acid by the Somogyi, the Hagedorn-Jensen, and the hypoiodite methods (108). The results obtained with the copper sulfate and hypoiodite methods were 60 and 36% lower, respectively, than those obtained with the ferricyanide method. 

Since L-sorbose is a reducing sugar a number of methods for its determination, based on this property, have been reported. Titration with the ceric sulfate, potassium ferricyanide reagent showed a fructose to sorbose ratio of 1.1,86 Cupric citrate87 as well as cupric tartrate87 reagents appear to be equally useful. 

Reducing power of sugars is the basis of a number of classical analytical methods. Iodine, alkaline ferricyanide and other reagents have been used for analytical purposes. 

This method for determining reducing sugars (7) is based on the reduction of ferricyanide ions in alkaline solution by a reducing sugar. The ferrocyanide produced can then react with a second mole of ferricyanide producing the ferric-ferrocyanide (Prussian blue) complex. Potassium... 

A method of blood sugar estimation based on the ability of glucose to reduce ferricyanide to ferrocyanide. The ferricyanide remaining is determined iodometrically. 

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