Rapid Determination of Trace Elements in Macedonian Grape Brandies for Their Characterization and Safety Evaluation

Abstract

A graphite furnace atomic absorption spectrometry (GFAAS) was used for determination of trace elements (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in “rakija” samples, a grape brandy traditionally produced in Republic of Macedonia by distillation of grape pomace or wine, for characterization and safety evaluation. Cd, Pb, Cr, and Ni were determined directly, while Cu, Fe, Mn, and Zn were quantified after appropriate dilution. The calibration curves of all elements were linear with correlation coefficients (R 2) ranging from 0.9995 to 0.9998. The accuracy of the method was checked with a standard addition method showing good repeatability and reproducibility (relative standard deviation (RSD) <10 %). Relationship between several metal concentrations (Cu, Fe, Mn, Zn) in brandies and distillation system (homemade/industrial) on one side and aging mode (oak barrels/oak chips) on the other side were demonstrated. Two homemade brandies showed Cu, Fe, and Zn concentrations higher than industrial distillates and thus were found to be not safe for consumption because of Cu and Zn over the maximum allowed values. For the industrially produced brandies, Mn was identified to be a suitable marker related to aging with oak chips regardless variety, while Cu a marker for the influence of oak chip type. Principal component analysis applied on the content of elements clearly showed a good separation in terms of distillation and aging method.