An Smri-cts Comparison of near Infrared (nir) Polarimetry

Leaded pol analyses are used in sugar factories as an estimation of sucrose for factory control purposes and for cane payment. Health and environmental concerns associated with the use of lead for sample clarification has put pressure on the use of this method. Near infrared (NIR) polarimetry has been investigated as an alternative worldwide and the South African sugar industry has decided to replace the leaded pol analysis with NIR polarimetry for factory control purposes. The new method uses a NIR light source which does not require the test solution to be of low colour. Lead clarification can therefore be replaced by a simple filtration step to remove solution turbidity. Suitability of the use of NIR polarimetry by the Cane Testing Service (CTS) was established using a number of comparisons between CTS centres and the SMRI during the 2004/05 season. Previous comparisons were done only at the SMRI. Results are presented and discussed together with the change in method, equipment and other considerations.