Efficiency of two digestion methods in determining the presence of metals (Cd, Cu, Cr, Pb and Zn) in geopropolis produced by Melipona scutellaris

Josemário Santana Bonsucesso,Andreia Santos Do Nascimento,Antônio Leandro Da Silva Conceição,Carlos Alfredo Lopes De Carvalho,Fabio De Souza Dias

doi:10.15446/rev.colomb.quim.v50n2.90293

Josemário Santana Bonsucesso, Andreia Santos Do Nascimento + Show 3 more

Open Access

https://doi.org/10.15446/rev.colomb.quim.v50n2.90293

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Abstract

This study evaluates the efficiency of acid extraction and total digestion to determine the presence of metals in geopropolis produced by the stingless bee Melipona scutellaris. Geopropolis samples were collected at five meliponaries in the city and in the metropolitan region of Salvador, Bahia State, Brazil. The sample treatment methods comprised acid extraction and total digestion. The Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) technique was used to quantify Cd, Cu, Cr, Pb, and Zn. Geopropolis samples submitted to both digestion methods showed statistical differences. For both methods, Cr and Zn showed the highest concentrations, while those of Cd were the lowest. The Cr concentration for determination by total digestion was 37.53 mg/kg, while for acid extraction it was 32.90 mg/kg. For Zn, the concentration was 17.65 mg/kg and 8.85 mg/kg for total digestion and acid extraction, respectively. The total digestion method showed the highest concentrations of the metals evaluated; however, acid extraction (USEPA 3050b) is a more straightforward procedure for metal evaluation in geopropolis samples and presented values that support the use of geopropolis as a bioindicator. The acid extraction method USEPA 3050b, in combination with detection using ICP OES, showed efficiency in analyses carried out to determine metals in geopropolis.

Highlights

Sample digestion is usually necessary to determine total metal concentrations in a material, since the application of different acid digestion methods can release different amounts of analytes in the digested solution [1,2,3]
This study evaluates the efficiency of acid extraction and total digestion to determine the presence of metals in geopropolis produced by the stingless bee Melipona scutellaris
The authors used a microwave-assisted acid digestion, indicating the precision of the acid extraction and total digestion methods used in the present study, stressing that the advantage in using acid extraction in the preparation of the sample is greater simplicity in relation to total digestion

Summary

Introduction

Sample digestion is usually necessary to determine total metal concentrations in a material, since the application of different acid digestion methods can release different amounts of analytes in the digested solution [1,2,3]. The total digestion of samples containing silicates generally includes mixtures of nitric, hydrochloric and hydrofluoric acids (HNO3, HCl, and HF respectively). This procedure is used to release analytes from the adsorbed, exchangeable, oxidizable, reduced and residual fractions of the sample matrix [6,7]. This study assesses the efficiency of acid extraction and total digestion to determine metals adsorbed in geopropolis produced by Melipona scutellaris

Material and methods

Procedures for sample digestion

Results and Discussion

Digestion Method

Conclusions