New approach for direct analysis of opaque solutions with high content of suspended solids: Determination of calcium and phosphate in raw sugarcane juice.

This paper presents a new analytical approach for element concentration determination in samples containing significant concentrations of dissolved and suspended interferences. The proposed system enables to segregate of the complex matrix, species of interest from other interferences with a minimum requirement of reagents and energy. For this purpose, a new cleanup chamber design was implemented with cationic and anionic resins employed under membrane form and the tangential flow of the solution avoided the drawbacks commonly attributed to the packed and fluidized bed columns, such as the formation of preferred paths, increasing hydrodynamic pressure and clogging. The element concentration determination was colorimetrically performed with an automatic flow analysis system. The strategy was validated with the concentration determination of calcium and phosphorus in raw sugarcane juice. Quantification limit of 0.48 to calcium and 1.13 mg L-1 to phosphorus, linear range between 1 and 50 mg L-1, with RSD of 0.50 and 1.50% (n = 11) respectively.