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A simple and miniaturized protocol was developed for chloride extraction from Brazilian pre-salt crude oil for further salt determination by colorimetry. In this protocol, the colorimetric analysis of chloride using digital images was carried out in an aqueous phase obtained after a simple and miniaturized extraction carefully developed for this purpose. A portable device composed of a homemade 3D-printed chamber with a USB camera was used. The PhotoMetrix app converted the images into RGB histograms, and a partial least squares (PLS) model was obtained from chemometric treatment. The sample preparation was performed by extraction after defining the best conditions for the main parameters (e.g., extraction time, temperature, type and volume of solvent, and sample mass). The PLS model was evaluated considering the coefficient of determination (R2) and the root mean square errors (RMSEs)—calibration (RMSEC), cross-validation (RMSECV), and prediction (RMSEP). Under the optimized conditions, an extraction efficiency higher than 84% was achieved, and the limit of quantification was 1.6 mg g−1. The chloride content obtained in the pre-salt crude oils ranged from 3 to 15 mg g−1, and no differences (ANOVA, 95%) were observed between the results and the reference values by direct solid sampling elemental analysis (DSS-EA) or the ASTM D 6470 standard method. The easy-to-use colorimetric analysis combined with the extraction method's simplicity offered a high-throughput, low-cost, and environmentally friendly method, with the possibility of portability. Additionally, the decrease in energy consumption and waste generation, increasing the sample throughput and operators' safety, makes the proposed method a greener approach. Furthermore, the cost savings make this a suitable option for routine quality control, which can be attractive in the crude oil industry. [ABSTRACT FROM AUTHOR]

Mobile devices were used to quantify ethanol content—via colorimetry—in cachaça samples to great analytical precision. Ethanol from the spirits reacted with ceric ammonium nitrate (CAN) and nitric acid (NA) to form a red-colored complex. Images from the reaction were taken over time using a smartphone device and processed using software PhotoMetrix Pro® via partial least squares (PLS). A priori, Doehlert matrix was used for optimization of reagents concentration in the complexation reaction, with hierarchical cluster analysis (HCA) as estimation method and a flatbed scanner as measuring tool. When compared with the UV-VIS reference method, results from mobile device imaging presented a root mean square error of prediction (RMSEP) of 0.0677% (v/v). A t test showed there is no significant difference between methods (P < 0.05). [ABSTRACT FROM AUTHOR]

A method for the digestion of polymeric waste electrical and electronic equipment (WEEE) by microwave-assisted ultraviolet wet digestion (MAWD-UV) was proposed for the first time allowing us to obtain a single digest for the further determination of Br, Cd, Cr, Hg, Pb and Sb according to the Restriction of the Use of Certain Hazardous Substances (RoHS) directive. The determination of bromine and metals was carried out by inductively coupled plasma mass spectrometry (ICP-MS). The efficiency of MAWD-UV was compared with that obtained without the UV lamp, using 1 to 7 mol L−1 HNO3 and HNO3 plus HCl (5 + 1) mixtures. A wet acid digestion method combined with ICP-MS, as well as neutron activation analysis (NAA), was used to obtain reference values. Although the UV lamp improved the digestion, thus allowing for the use of diluted solutions, possible losses of bromine were observed using a 3 mol L−1 HNO3 solution. After a careful optimisation, a diluted solution containing 0.5 mol L−1 HNO3 + 0.5 mol L−1 HCl + 5.3 mol L−1 H2O2 provided results that were in agreement with the reference values for bromine and metals in the same digest solution. Spike recoveries ranged from 90 to 113% for all the analytes. The results were compared with the values of certified reference materials (ERM 680k and ERM 681k, low-density polyethylene) digested by MAWD-UV and no statistical difference was observed, except for Cr. Limits of quantification using ICP-MS ranged from 0.010 μg g−1 (Cd) to 4.5 μg g−1 (Br) that were suitable according to the RoHS directive. The MAWD-UV method allowed for the single digestion method using diluted acids and did not require different digestion solutions for bromine and metals, thus providing suitable digestion efficiency without bromine losses. [ABSTRACT FROM AUTHOR]