Division 4.2 Analysis

Adjust the water circulation system (3.3) to operate at the required temperature (between 15 and 25 °C) and set it in operation so that the prisms of the refractometer (3.1 or 3.2) reach the same temperature, which must be kept constant to within 0,5 °C during the analysis.

Bring the test solution (4.1) to a temperature similar to that to be used in the analysis. Place a small quantity of the test solution (two or three drops are sufficient) on the fixed prism of the refractometer (3.1 or 3.2) and immediately adjust the movable prism. The field of vision must be suitably illuminated. A sodium vapour lamp may be used to obtain more precise results (particularly if the products are coloured or dark).

Move the dividing-line between the light and dark areas of the field of vision so that it coincides with the intersection between the cross-hairs on the scale and read off the value of the refractive index on the percentage by mass of sucrose according to the type of apparatus used (3.1 or 3.2).