Sugars solubility determination

Matrix Components The term matrix component refers to the constituents in the material aside from those being determined, which are denoted as analyte. Clearly, what is a matrix component to one analyst may be an analyte to another. Thus, in one hand for the case of analyses for elemental content, components such as dietary fibre, ash, protein, fat, and carbohydrate are classified as matrix components and are used to define the nature of the material. On the other hand, reference values are required to monitor the quality of determinations of these nutritionally significant matrix components. Hence, there is a challenging immediate need for certified values for dietary fibre, ash, protein, fat, and carbohydrate. Concomitantly, these values must be accompanied by scientifically sound definitions (e.g. total soluble dietary fibre, total sulpha-ted ash, total unsaturated fat, polyunsaturated fat, individual lipids, simple sugars, and complex carbohydrates). 

Values from Refs. (272,646) are derived from measurements of the solubility of calcium sulfate in solutions of the respective sugars (at 298K, 0.2stability constants from solubility measurements has been reviewed - see Ref. (225). 

Temperature. In most cases, the solubility of the material which is being extracted will increase with temperature to give a higher rate of extraction. Further, the diffusion coefficient will be expected to increase with rise in temperature and this will also improve the rate of extraction. In some cases, the upper limit of temperature is determined by secondary considerations, such as, for example, the necessity to avoid enzyme action during the extraction of sugar. 

Applications of the Karl Fischer method are numerous food stuffs (butter, margarine, powdered milk, sugar, cheese, processed meats, etc.), solvents, paper, gas, petroleum, etc. Before the determination can be made, solid components that are not soluble must either be ground into powders, extracted with anhydrous solvents, eliminated as azeotropes or heated to eliminate water. Problems are encountered with very acidic or basic media that denature reactants and transform ketones and aldehydes into acetals that interfere with the titration. Special reagents must be used in these instances. 

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