Multielemental determination in sugarcane products from the southern region of Brazil by microwave induced plasma optical emission spectrometry after acid decomposition with a reflux system

Abstract

Microwave induced plasma optical emission spectrometry (MIP OES) was employed to determine the concentrations of macro and micronutrients (Ba, Ca, Cu, Fe, K, Mg, Mn and Na) in products derived from sugarcane: sugars (refined, crystal, demerara and brown) and derived products (molasses and brown sugar candy) produced in the southern region of Brazil. The sample preparation was performed by acid decomposition with a reflux system under optimized conditions: 1000 mg of sample and 5.0 mL of concentrated nitric acid for 4 hours at 150 °C and addition of 1.0 mL of hydrogen peroxide. At the end we obtained a procedure that provides analytical solutions in accordance with the established parameters of acidity and dissolved solids as per the MIP OES spectrometer manufacturer's recommendations. The accuracy was evaluated by the analyte addition tests (80 to 119%). The limits of detection, in mg kg⁻¹, were 0.03 (Ba); 0.03 (Ca); 0.04 (Cu); 0.08 (Fe); 0.18 (K); 0.03 (Mg); 0.02 (Mn) and 0.26 (Na). The concentrations of the analytes in the different samples varied according to the degree of processing, since higher values appeared for the less processed samples, i.e. brown sugar, molasses and brown sugar candy.