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In this work, microwave-induced plasma optical emission spectrometry was applied for multielement determination in South American wine samples. The analytes were determined after acid digestion of 47 samples of Brazilian and Argentinian wines. Then, logistic regression, support vector machine, and decision tree for exploratory analysis and comparison of these algorithms in differentiating red wine samples by region of origin were carried out. All wine samples were classified according to their geographical origin. The quantification limits (mg L -1 ) were P: 0.06, B: 0.08, K: 0.17, Mn: 0.002, Cr: 0.002, and Al: 0.02. The accuracy of the method was evaluated by analyzing the wine samples by ICP OES for results' comparison. The concentrations in mg L -1 found for each element in wine samples were as follows: Al (< 0.02-1.82), Cr (0.15-0.50), Mn (< 0.002-0.8), P (97-277), B (1.7-11.6), Pb (< 0.06-0.3), Na (8.84-41.57), and K (604-1701), in mg L -1 ., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

[Display omitted] • Ultrasonic degradation was performed for a metals determination in wine by MIP OES. • Application of Doehlert design for optimization ultrasound assisted procedure. • The Procedure is simple, robust and enabled the determination of multi-elements in wine samples by MIP OES. • In the optimization of multiple analytical responses, the desirability function was used for this objective. 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 São 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. [ABSTRACT FROM AUTHOR]

• Ultrasound-dispersive liquid–liquid microextraction for the extraction of melatonin in wine samples. • Aplication of Doehlert matrix for the optimization of analytical method. • The method was applicate in the determination of melatonin in Brazilian and Argentinevwine salmple. • The method proposed presented lows limits of detection and quantification, good precision and accurate. In the present work, a method based on the Ultrasound-dispersive liquid–liquid microextraction (US-DLLME) for the preconcentration of melatonin in Brazilian and Argentinian wine samples prior to the determination by reverse phase high performance liquid chromatography with diode array detector HPLC-DAD was developed. Sample prep optimization was carried out in two stages. First, a full factorial design was executed to evaluate the variables significance. The second step consisted of significant variables optimization (pH, extraction volume, sonication time, centrifugation time) using a Doehlert matrix to determine the critical values. Optimal US-DLLME extraction conditions were as follows: pH of 4.5, sonication time of 6.8 min, centrifugation time of 2.5 min, extractor volume of 250 µL and 5.0 mL of sample. The organic phase was retrieved with a microsyringe to a glass tube, dried and diluted with the mobile phase prior injection. The method presented a limit of detection (LOD) of 0.23 μg L−1 and a limit of quantification (LOQ) of 0.70 μg L−1. The precision expressed as relative standard deviation (R.S.D.) was 0.8% and 1.9% at 10.0 and 1.0 μg L−1, respectively. Accuracy was confirmed by comparison of the results found by the proposed methods with an alternative method, and spike tests with recuperations ranging from 92 to 103%. The analyzed samples showed concentrations varying from 2.2 to 5.0 μg L−1. [ABSTRACT FROM AUTHOR]