Effect of modifiers for As, Cu and Pb determinations in sugar-cane spirits by GF AAS

A fast, low-cost, sensitive, selective, and non-laborious method based on functionalized magnetic nanoparticles, magnetic solid-phase extraction, and fluorescent carbon dots for the fluorimetric determination of copper in wines without prior sample treatment

A new fluorimetric method for copper(II) determination in wines was developed combining functionalized magnetic nanoparticles (FMNP) and fluorescent carbon dots (FCD). To produce FMNP, Fe₃O₄ was coated with Al₂O₃ forming Fe₃O₄@Al₂O₃ core-shell magnetic nanoparticles and functionalized with PAN and SDS. FCD was synthesized from pineapple juice through hydrothermal carbonization. For copper determination, aliquots of wine, the FMNP dispersion, and Britton-Robinson buffer (pH = 4.0) were mixed under stirring to allow the adsorption of copper by FMNP. Cu-FMNP complex was attracted by a niobium magnet and, after discarding the non-magnetic material, the copper(II) ions were eluted with an FCD dispersion before fluorescence quenching measurements. The proposed method presented a linear range from 0.020 to 0.100 mg L^-1 (r² = 0.9953), RSD (intraday) < 3.0%, and recovery rates from 96 to 105 %. FMNP and FCD properties permitted extraction/preconcentration/determination of copper within 1 min with an enrichment factor of nine and without prior sample treatment.

Lead contamination in food consumed and produced in Brazil: Systematic review and meta-analysis

This systematic review (SR) evaluated evidence of lead (Pb) levels in foods consumed or produced in Brazil. Seventy-seven publications were included in this review, corresponding to a total of 8466 food samples that were grouped into 12 food categories with similar characteristics (infant food; sugar; beverages; meat and meat products; nuts, cocoa and products; fruits and fruit products; grains, cereals and products; milk and milk products; eggs; oil and fat spreads; vegetables and vegetable products and other foods). The random model was used to establish levels of Pb in food categories. We used the software R® to perform the meta-analysis. The overall occurrence of Pb was estimated at 0.0541 mg/kg, and ranged from 0.0004 mg/kg to 0.4842 mg/kg. The SR and meta-analysis presented relevant results about Pb contamination on foods, despite the high heterogeneity. They were understood as a viable strategy to answer questions regarding prevalence of Pb which is necessary for the risk assessment of Pb intake in foods.

Evaluation of raw soapstone (steatite) as adsorbent of trace elements present in Brazilian spirits

The impact of soapstone (steatite) upon inorganic element contaminant concentrations in alcoholic beverages was investigated. Concentrations of As, Cd, Cu, Ni and Pb levels in 8 Brazilian spirits plus an alcoholic simulant were initially measured, and then measured following each 24h cycle of exposure to raw soapstone cups, for a total of 4 cycles/sample. The results were compared to the levels established by Brazilian and German regulations. The contact between the spirits and the soapstone reduced the Cu content by up to 50.4% and increased the Ni content by up to 622.2%, especially in the first contact cycle. The exposure of spirits to the soapstone exhibits a linear reduction in the Pb content (18.3-54.5%) while As and Cd levels remained unaltered throughout the experiments. In conclusion, crude soapstone in contact with alcoholic solutions acts as an adsorbent of trace elements (Cu and Pb) while releasing Ni.

A new and sensitive method for the determination of trace arsenic using differential pulse polarography

A new and simple differential pulse polarographic method has been developed for the trace determination of arsenic. When selenite was added into solutions of some ions such as copper, lead, cadmium, zinc, and chromium, their differential pulse polarographic peak decreased. A new reduction peak appeared at a more positive potential than the ion present and it was always higher than the corresponding reduction peak of the ion. Thus, we made use of this interference for the trace determination of As(III). By the addition of selenite onto As(III), a new As−Se intermetallic compound peak was formed at about −0.35 V (pH at about 1.0–2.0). The trace arsenic concentration could be determined simply from this peak by the addition of standard arsenic into a polarographic cell. In the presence of large amounts of selenite, 2 × 10−7 mol/L As(III) could be determined from this peak precisely. With the newly established method, the limit of detection was 1 × 10−8 mol/L (S/N = 3). Among the most common cations and anions, only Cd−Se and Pb−Se intermetallic compound peaks had an overlap with the As−Se peak. This interference could be eliminated simply by the addition of EDTA. This method was applied successfully for the determination of arsenic in a digested beer sample.

Application of zirconium-iridium permanent modifier for the simultaneous determination of lead, cadmium, arsenic, and nickel in atmospheric particulate matter by multi-element electrothermal atomic absorption spectrometry

A novel and robust method for the simultaneous determination of lead, cadmium, arsenic, and nickel in atmospheric particulate matter by multi-element electrothermal atomic absorption spectrometry was developed, using zirconium-iridium coating as permanent modifier (140 μg Zr and 4 μg Ir). After 300 atomization cycles, it was necessary to add 2 μg of Ir. Due to the varying concentrations of Pb in atmospheric particulate matter, lead was monitored at two wavelengths, at the less sensitive line of 261.4 nm for high concentration samples (>20 μg L(-1)) or at 283.3 nm for the low concentration samples. Matrix-matched calibration had to be performed for quantitative recoveries (96-102 %). Following this approach, the four elements were determined in atmospheric particulate matter samples from an industrial area near the city of Athens in two different time periods (cold-warm) with limits of detection of 5.5 ng m(-3) for Pb at 261.4 nm and 0.29 ng m(-3) at 283.3 nm, 0.019 ng m(-3) for Cd, 0.14 ng m(-3) for As, and 0.22 ng m(-3) for Ni. Lead, Cd, and As levels were very low, whereas Ni content was at comparable levels with other areas worldwide.