Abstract: The sucrose content of raw sugar, white sugar and some speciality sugars is determined by polarimetry in the near infrared (NIR) wavelength range (here typically 800 nm to 900 nm) and expressed in °Z of the international polarimetric sugar scale.
The international polarimetric sugar scale is exactly valid only for solutions of pure sucrose in water.
Deviations from the true sucrose content depend on the amount and kind of impurities.
Measurement in the NIR-range is nearly independent of coloured impurities, optically active impurities, however, will cause deviations.
The method is Officially adopted and may form the basis of sugar purchasing contracts, results, however, should be reported accompanied by a statement that “polarimetric measurement has been carried out without wet lead clarification”.
The absolute difference between two results obtained under repeatability conditions should be not greater than 0.16 °Z.
The absolute difference between two results obtained under reproducibility conditions should be not greater than 0.27 °Z.
Precision data are determined and valid only for raw sugar in the range of 97.5 °Z to 99.9 °Z.
If a choice is available to the user for the determination of polarimetric sucrose content of raw sugar, then ICUMSA® recommends that Method GS1-1 is used preferentially.
Online Access to ICUMSA Method GS1-2 (2022)
Access to the online Version of ICUMSA Method GS1-2 (2022) can be obtained from the Sugar Industry Website, operated by Bartens. The online access for two years costs EUR30 (+ 19 % VAT for German and EU citizens without EU VAT No.).