Polarization of raw sugar without basic lead acetate: International collaborative test

With the determination of the 100 degree point and the rotatory dispersion of quartz at near infrared (NIR) wavelengths reported at ICUMSA's 22nd Sess ion at Berlin in 1998, it became possible to properly specify an alternativ e polarization method for raw sugar that uses NTTC wavelengths and does not require the use of a basic lead acetate clarifying agent. On instructions from ICUMSA's Referee for Raw Sugar, Mr Ross Urquhart, Cent ral Laboratory drafted an ICUMSA Method for polarization using as a basis t he method already in use by the US sugar industry. This draft method was th en subjected to a collaborative test conducted among ten participating labo ratories drawn from seven countries according to internationally accepted I UPAC protocols. The r and R values of 0.16 degreesZ and 0.27 degreesZ compa re reasonably with those for the "wet lead" method whose r and R values of 0.10 degreesZ and 0.25 degreesZ were established in a comparable test.