THE DETERMINATION OF ICUMSA SUGAR SOLUTION COLOUR AT pH 6.4: RECENT DEVELOPMENT IN THE ICUMSA

摘要

It was brought to the notice of ICUMSA (Brazil, 2006) that sugars in their purest form ionize or dissociate and thus have their own pH values by definition. It was developed reasoning for the pH = 6.4 quite well and put forth the same as reference pH for ICUMSA color determinations for global sugar trade. To establish the method, it has been tested collaboratively as per "TUPAC-1987 protocol" using MES, MOPS and MOPSO buffers. Color analysis using aforesaid buffers at the proposed pH = 6.4 were founds statistically and economically equivalent. Furthermore, better chemical stability and improved solubility over MES and MOPS, makes MOPSO more suitable buffer at pH 6.4 from practical point of view. However, under the present circumstances, MOPS buffer at pH = 6.4 seem more acceptable. The detailed results were presented before ICUMSA (Florida, 2008) and ICUMSA has recommended an International collaborative study on the method proposed at pH = 6.4 with MOPS buffer along with existing color method GS9/1/2/3-8 with white sugar, plantation white sugar and other types of sugars with wide color range. The method format has been given as Appendix 1.