Natural radionuclides as dirt tracers in sugar cane consignments

Soil is usually carried to the mills, as an impurity in sugar cane, leading to economic drawbacks for the industry. The quantification of this dirt is important to identify its causes and for routine quality control. Several methods have been used for this purpose, however, no single one has been pointed out as an industrial standard. The use of a gamma-ray emitting radionuclide of natural occurence was investigated and, after several soil and cane radioactivity analyses, Pb-212 was chosen as the best tracer. Calibration curves developed with the addition of soil in clean cane, from 0 to 10% (dry mass), demonstrated the linearity of the method. Analyses of eleven samples taken from consignments showed that the procedure was consistent and reliable when compared to the traditional ash method.