Determination of Cl, Br and I in granola: Development of an accurate analytical method using ICP-MS.

Microwave-induced combustion (MIC) system for further Cl, Br, and I determination in granola by inductively coupled plasma mass spectrometry (ICP-MS) was proposed. A high sample mass of granola was pressed as pellets and inserted into the proposed MIC system. Water and NH4OH were evaluated as absorbing solutions. The accuracy was estimated by the analysis of two certified reference materials and also by spike recoveries. Using the optimized conditions (zirconium ball milling, 1 g of granola and 6 mL of 50 mmol L-1NH4OH), the agreement with the certified values ranged from 94 to 98% and recoveries higher than 95% were obtained. Low carbon concentration in digests (<25 mg L-1) was achieved, minimizing interferences by ICP-MS. Blanks were negligible and only diluted solutions were required. The concentration in samples ranged from 322 to 896, 0.618 to 0.980 and < 0.002 to 0.181 µg g-1 for Cl, Br and I, respectively.

Multivariate optimization of ultrasound-assisted liquid-liquid microextraction based on two solvents for cadmium preconcentration prior to determination by flame atomic absorption spectrometry.

A method based on ultrasound-assisted emulsification liquid-liquid microextraction (USAEME) for cadmium determination by flame atomic absorption spectrometry (FAAS) was developed in this work. USAEME is based on the use of the mixture of 1,2-dichloroethane and trichloroethylene as an acceptor phase, 2-(2-bromo-5-pyridylazo)-5(diethylamino)phenol (Br-PADAP) as a chelating reagent, and ethanol as a dispersive solvent. The composition of the extraction and dispersive solvents, the volume of the extraction solvent, pH, and the sonication time were optimized using the multivariate strategy. The limits of detection and quantification calculated under optimum conditions were, respectively, 0.39 and 1.33 µg L-1, and the obtained enrichment factor was 21. The accuracy was tested by the analysis of certified reference materials. The method was applied to cadmium determination in bivalve mollusks, water, and urban wastewater from Pontal Bay, Bahia, Brazil. The proposed method is simple, fast, and efficient, and uses small amounts of organic solvents for the determination of cadmium.

Mixture Design and Doehlert Matrix for the Optimization of the Extraction of Phenolic Compounds from Spondias mombin L Apple Bagasse Agroindustrial Residues.

In this study, we have determined, using RSM (mixture design and Doehlert matrix), the optimum values of the independent variables to achieve the maximum response for the extraction of total phenolic compounds from Spondias mombin L bagasse agroindustrial residues in order to preserve their antioxidant activity. The extraction of phenolic compounds, as well as their antioxidant capacity and the capacity to scavenge ABTS, was determined by the modified DPPH method at different periods of time, temperature, velocity of rotation and solvents concentration. We observed that the optimum condition for the highest antioxidant yield was obtained using water (60.84%), acetone (30.31%), and ethanol (8.85%) at 30°C during 20 min at 50 rpm. We have also found that the maximum yield of total phenolics was 355.63 ± 9.77 (mg GAE/100 g), showing an EC50 of 3,962.24 ± 41.20 (g fruit/g of DPPH) and 8.36 ± 0.30 (µM trolox/g fruit), which were measured using DPPH and ABTS assays. These results suggest that RSM was successfully applied for optimizing the extraction of phenolics compounds thus preserving their antioxidant activity.