Systematic evaluation of sample preparation method for simultaneous voltammetric determination of Zn, Cd, Pb, and Cu in macroalgae

Abstract

In this paper, four mineralization procedures of macroalgae were evaluated. Two methods used a closed system microwave) and two an open system (strong acid and ultraviolet radiation). Zn, Cd, Pb, and Cu were determined by square-wave anodic stripping voltammetry (SWASV) and graphite furnace atomic absorption spectrometry (GF AAS) was used as comparative method. Determinations of total, inorganic, and organic carbon, as well as the study of matrix effect, were performed. It could be observed that, although mineralizations accomplished with open systems presented lower levels of total carbon and lower matrix effect, the determinations of compounds from standard reference material (SRM) did not show acceptable recoveries. However, the mineralization using microwave (closed system—methods A and B) showed recovery within the acceptable range to all compounds (78 to 115 %), and after statistical analysis, it can be concluded that the method A is more accurate than the method B; therefore, most suitable for macroalgae mineralization and simultaneous determination of Zn, Cd, Pb, and Cu by voltammetry.