A DLLME method for extraction and preconcentration of Cd and Pb from soft drinks and further determination by GF AAS was developed. Important parameters of DLLME such as the type and volume of dispersive and extraction solvents, concentration of DDTC (complexing agent) and pH were evaluated. Better results were obtained using 500μL of acetone for Cd and 700μL of acetonitrile for Pb as dispersive solvents, 60μL of CCl as extraction solvent for both analytes and 500μL of 1.5% DDTC solution. Accuracy was evaluated by recovery assays and ranged from 91 to 113% for Cd and from 95 to 108% for Pb, with RSD below 10 and 7%, respectively. The LODs were 0.006 and 0.072ngL for Cd and Pb, respectively. The optimized method was applied for the determination of Cd and Pb in soft drinks with different brands and flavours.

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A method for determining low levels of As and Cd by dispersive liquid-liquid microextraction (DLLME) and inductively coupled plasma mass spectrometry (ICP-MS) was proposed. The following parameters that affect extraction efficiency were investigated: type and volume of extraction solvent (1000 µL acetone), type and volume of dispersive solvent (75 µL carbon tetrachloride), amount of ammonium pyrrolidinedithiocarbamate and sodium diethyldithiocarbamate as chelating agents, sample mass (0.5 g in 10 mL ultrapure water), pH of sample solution (2.0) and number of washing steps (one). Accuracy was evaluated by analytes determination in sugar samples by ICP-MS after digestion by microwave-induced combustion (MIC). No significant difference was observed between results of the proposed DLLME method and MIC in the case of both analytes. Instrument calibration was performed by the standard addition method and good linearity was achieved. Limits of quantification (LOQs) were 0.7 and 0.2 ng g -1 for As and Cd, respectively. The main advantages of this method are relatively high sample mass, low dilution, suitable preconcentration factors and significantly low LOQs (ng g -1 range). When the proposed method was used for determining As and Cd in four sugar samples, their concentrations ranged from 1.13 to 2.95 ng g -1 and from 0.31 to 0.43 ng g -1 , respectively.Keywords: dispersive liquid-liquid microextraction, sugar, arsenic, cadmium, inductively coupled plasma mass spectrometry IntroductionSugar has been widely consumed around the world by people of all ages, since it is an important ingredient found in several products, such as sweets, softdrinks and bread. 1,2 Similarly to other food, it is prone to contamination by toxic elements throughout its production and manufacturing processes.3 Some elements can be classified into essential or toxic, depending on the role they play in the metabolism of living organisms. Ca, Cu and Zn are essential for life whereas As, Cd and others do not have any known biological function and may be toxic, depending on their concentrations, thus posing potential risks to human health. [4][5][6][7] Arsenic may cause several health problems with mutagenic, carcinogenic and teratogenic effects. In humans, it can affect neurological, cardiovascular and respiratory systems, besides causing hypertension. [7][8][9] Cadmium is the most toxic element to humans, since it leads to renal failure, hypertension, emphysema and carcinogenic hazards, mainly in the kidney and prostate. 8,9 Therefore, As and Cd must be considered toxic even at low concentrations and must be monitored in the environment, food and beverages.Several techniques have been developed for simultaneous element determination at ultratrace levels in food samples. Inductively coupled plasma optical emission spectrometry (ICP-OES) 10 and inductively coupled plasma mass spectrometry (ICP-MS) 11 are the most successful examples. Regarding these techniques, the latter, which is the most sensitive, versatile and suitable one for routine applicati...

The present work evaluated the effect on charge transfer in functionalized TiO 2 nanostructured systems using different binders. We highlight the conditions required to form self-assembled systems by varying the number of layers, as well as by substituting them for an organic binder, cysteine. Additionally, we study the pH effect of the precursor solution (HAuCl 4 ) on gold nanoparticles (AuNPs) formation. The morphological characterization allowed us to determine the percentage of Au atoms on the surface of the synthesized nanoparticles. Inductively coupled plasma mass spectrometry (ICP-MS) analysis determined the amount of gold deposited on the TiO 2 surface, which ranged from 4.56 to 253.00 ng mm -2 depending on the system used. Based on Fourier-transform infrared spectroscopy (FTIR) and Raman analysis, it was possible to propose a photolysis mechanism for AuNP formation in accordance with the change in the binders. The different systems were subjected to hydrogen photogeneration by a water splitting process, resulting in 2.02 μmol cm -2 of hydrogen production for cysteine binder [Cys+HAuCl 4 -2.7]. There proved to be an excellent synergy between the morphological aspects, crystallinity, and stability of this arrangement.