Refractometric dry substance content – The mass fraction of dissolved solids of a sugar-containing solution in g/100 g, determined using a refractometer.
Measurement of the refractive index of sugar solutions is used as a rapid method for the approximate* determination of the mass fraction of dissolved solids in g/100 g, i.e., their dry substance content.
*NOTE 1: For pure sucrose solutions the exact dry substance content of the solution is calculated from the refractive index measurement using the algorithm given in ICUMSA SPS-3.
For technical sucrose solutions which have additions of unknown non-sugars, the refractive index measurement gives the dry substance content in a relatively good approximation, depending on the purity of the solution.
*NOTE 2: In case of pure and technical solutions of glucose, fructose, invert sugar and invert sugar/sucrose blends, the refractive index measurement gives the dry substance content of the solution using the respective algorithm given in ICUMSA SPS-3 (for technical solutions in relatively good approximation).
NOTE 3: Results of the measurement using a refractometer should include the term “refractometric”, i.e., refractometric dry substance content (wDS,ref).