Metals in geopropolis from beehive of Melipona scutellaris in urban environments.

Geopropolis, a different type of propolis, presents a mixture of resin and exudates, containing wax, silt, and sand particles. This product has been the subject of research interest for its physicochemical properties, economic importance, and likely for environmental monitoring. The determination of toxic metals in hive products has been reported as an efficient tool for environmental monitoring. As the honey production is now common in urban environments, this study aimed to determine the concentration of toxic metals in the Melipona scutellaris geopropolis of the Metropolitan Region of Salvador, Bahia. Geopropolis and soil samples were collected from seven important beehives between June 2015 and July 2016. After EPA 3050B acid digestion procedure, metals were determined by ICP OES. As the geopropolis is partially made from soil, the values of Cr and Fe were extremely more important than the values reported in propolis, wax, and honey found in other worldwide studies. It gives different characteristics to this product depending on the location of the hive and characterizes it as an efficient integrating indicator of soil pollution. Using the enrichment factor, we determined that the soils around the meliponary are not or only slightly polluted by Cu, Cr, Ni, Pb and Zn. However, there was a shift in the particle size of geopropolis, being loamier and less sandy than the surrounding soil. In such case, a higher metal content could be expected, though no metal enrichment in the geopropolis was found, even a decrease in zinc, possibly due to the exclusion of metals by bees, was noted. Nevertheless, the results on the proportions of lithogenic metal and anthropogenic metal indicate that some metals have an external origin (about 20% for Ni and Cu). Geopropolis can be considered as a good environmental indicator even in low contaminated areas.

Preconcentration and determination of copper in tobacco leaves samples by using a minicolumn of sisal fiber (Agave sisalana) loaded with Alizarin fluorine blue by FAAS.

In the present study, a minicolumn of sisal fiber loaded with alizarin fluorine blue is proposed as a preconcentration system for copper determination in tobacco leaf samples by flame atomic absorption spectrometry. During the optimization procedure, a two level full factorial design (2(4)) was used at the preliminary evaluation of four factors, involving the following variables: sampling flow rate, elution flow rate, buffer concentration and pH. Regarding the studied levels, this design has shown that buffer concentration and pH were significant factors. The experimental conditions established in the optimization step were: pH=4.75, buffer concentration of 0.005 mol L(-1) for elution with HCl 1.0 mol L(-1) this system allows the determination of copper content with a detection limit (LD) of 0.018 µg L(-1) and a quantification limit (LQ) of 0.061 µg L(-1) precision expressed as relative standard deviation (R.S.D.) of 4.65 and 5.07%, utilizing concentration of 10 and 2.0 µg L(-1), respectively, and a preconcentration factor of 75, for a sample volume of 50.0 mL. Accuracy was confirmed by copper determination in the standard reference material, NIST SRM 1570 a trace element units in Spinach Leaves and by spike tests with recovery levels ranging from 93 to 100%; the procedure was applied for copper determination in tobacco leaf samples collected in Cruz das Almas City, Bahia, Brazil. The achieved concentrations of the three samples analyzed varied from 0.15 to 0.52 µg g(-1).