Multiple response optimization of ultrasound-assisted procedure for multi-element determination in Brazilian wine samples by microwave-induced plasma optical emission spectrometry

In the present work, a method was developed, optimized, and validated for the determination of aluminum, manganese, lead, copper, cadmium, and zinc by microwave-induced plasma optical emission spectrometry of wine samples from the Sao Francisco Valley, northeastern Brazil. The samples were subjected to a sonochemical treatment aiming at the degradation of the sample matrix. To optimize the analytical procedure, initially, a two-level fractional factorial design was used to study five experimental variables and determine which ones significantly affected the analytical response. In a second step, the significant variables were optimized using the Doehlert matrix as the response surface methodology and the desirability function as a strategy to optimize multiple responses. The optimum conditions established were concentrations of nitric acid (2.3 mol L−1) and hydrogen peroxide (9%). The developed method is simple, fast, and precise, has a low operational cost and low limits of detection and quantification. The accuracy confirmed by spike tests with recoveries ranging from 104 to 118% and comparative analysis of the results obtained using the proposed method and digestion total procedure. The method was applied for multi-element determination in three wine samples.