Carbon and Nitrogen Isotope Ratios of Food and Beverage in Brazil.

Several previous studies on targeted food items using carbon and nitrogen stable isotope ratios in Brazil have revealed that many of the items investigated are adulterated; mislabeled or even fraud. Here, we present the first Brazilian isotopic baseline assessment that can be used not only in future forensic cases involving food authenticity, but also in human forensic anthropology studies. The δ13C and δ15N were determined in 1245 food items and 374 beverages; most of them made in Brazil. The average δ13C and δ15N of C3 plants were -26.7 ± 1.5‱, and 3.9 ± 3.9‱, respectively, while the average δ13C and δ15N of C4 plants were -11.5 ± 0.8‱ and 4.6 ± 2.6‱, respectively. The δ13C and δ15N of plant-based processed foods were -21.8 ± 4.8‱ and 3.9 ± 2.7‱, respectively. The average δ13C and δ15N of meat, including beef, poultry, pork and lamb were -16.6 ± 4.7‱, and 5.2 ± 2.6‱, respectively, while the δ13C and δ15N of animal-based processed foods were -17.9 ± 3.3‱ and 3.3 ± 3.5‱, respectively. The average δ13C of beverages, including beer and wine was -22.5 ± 3.1‱. We verified that C-C4 constitutes a large proportion of fresh meat, dairy products, as well as animal and plant-based processed foods. The reasons behind this high proportion will be addressed in this study.

A multi-purpose flow manifold for the spectrophotometric determination of sulphide, sulphite and ethanol involving gas diffusion: application to wine and molasses analysis.

A simple and rugged flow set up was designed for spectrophotometric determination of sulphide, sulphite and ethanol aiming at quality assessment of wines, control of industrial fermentation, and selection of yeast strain. The different assays involved gas diffusion through a Teflon planar membrane and were carried out after minor modifications in the manifold, namely reagent composition and total flow rate. Main figures of merit: linear analytical curves=0.50-6.0 mg L(-1)S(2-), 2.5-20.0 mg L(-1) SO3(-) and 5.0-25.0% (v/v) of ethanol; detection limits (3σ)=0.035 mg L(-1)S(2-), 0.2 mg L(-1) SO3(-) and 0.18% (v/v) of ethanol; peak height r.s.d.=2.18% for 4.03 mg L(-1)S(2-) spiked molasses, 2.21% for a 9.82 mg L(-1) SO3(-) wine and 2.07% for a typical wine (12.53% v/v of ethanol), sampling rate=15, 57 and 29 h(-1), reagent consumptions=1.9 µmol of N,N-dimethyl-p-phenylenediamine, 1.68 µg of Malachite green and 0.68 mmol Cr(VI) per determination, respectively.

Banana peel as an adsorbent for removing atrazine and ametryne from waters.

The feasibility of using banana peel for removal of the pesticides atrazine and ametryne from river and treated waters has been demonstrated, allowing the design of an efficient, fast, and low-cost strategy for remediation of polluted waters. The conditions for removal of these pesticides in a laboratory scale were optimized as sample volume = 50 mL, banana mass = 3.0 g, stirring time = 40 min, and no pH adjustment necessary. KF(sor) values for atrazine and ametryne were evaluated as 35.8 and 54.1 µg g(-1) (µL mL(-1)) by using liquid scintillation spectrometry. Adsorption was also evaluated by LC-ESI-MS/MS. As quantification limits were 0.10 and 0.14 µg L(-1) for both pesticides, sample preconcentration was not needed. Linear analytical curves (up to 10 µg L(-1)), precise results (RSD < 4.5%), good recoveries (82.9-106.6%), and a > 90% removal efficiency were attained for both pesticides. Water samples collected near an intensively cultivated area were adequately remedied.

A flow system with zone merging and zone trapping in the main reactor applied to spectrophotometric catalytic determination of cobalt in grasses.

A flow system with zone merging and zone trapping in the main reactor was proposed. The sample and reagent inserted aliquots merge together and the resulting zone is directed towards a displaceable reactor inside which its most concentrated portion is trapped. After the pre-set TRAP period, the handled sample is released towards detection. A comparison with an analogous flow system exploiting zone stopping revealed the superior characteristics of sampling rate and system operation; moreover, the sample inserted volume plays little influence on sampling rate. The system was applied to the spectrophotometric determination of cobalt in pastures, and enhanced figures of merit (sampling rate=18 h(-1); peak height r.s.d.=0.7%, detection limit=0.046 µg L(-1) Co; reagent consumption=330 µg of Tiron per measurement; 98%

Zone trapping/merging zones in flow analysis: a novel approach for rapid assays involving relatively slow chemical reactions.

A novel strategy for accomplishing zone trapping in flow analysis is proposed. The sample and the reagent solutions are simultaneously inserted into convergent carrier streams and the established zones merge together before reaching the detector, where the most concentrated portion of the entire sample zone is trapped. The main characteristics, potentialities and limitations of the strategy were critically evaluated in relation to an analogous flow system with zone stopping. When applied to the spectrophotometric determination of nitrite in river waters, the main figures of merit were maintained, exception made for the sampling frequency which was calculated as 189 h(-1), about 32% higher relatively to the analogous system with zone stopping. The sample inserted volume can be increased up to 1.0 mL without affecting sampling frequency and no problems with pump heating or malfunctions were noted after 8-h operation of the system. In contrast to zone stopping, only a small portion of the sample zone is halted with zone trapping, leading to these beneficial effects.