Direct Method for Determination of Al, Cd, Cu, and Pb in Beers In Situ Digested by GF AAS Using Permanent Modifiers

The object of the present study was to development of safe, reliable fast, and efficient methodologies for the direct determination of Al, Pb, Cu, and Cd in non-digested beer samples of widely consumed brand name beers sold in Brazil, using graphite furnace absorption spectrometry (GF AAS). Pyrolysis and atomization temperature curves of selected chemical modifiers (iridium, rhodium, ruthenium, zirconium, and non-modifier use) were used to stabilize each metal and sensitivity in a beer sample was diluted to 1:1 with 0.2 % v/v nitric acid after degasification. The best modifier for aluminum was permanent zirconium, with a characteristic mass of 4.2 pg (recommended is 10 pg), demonstrating a symmetrical peak with a corrected background using a deuterium arc lamp. For cadmium and copper, the best modifier was permanent ruthenium with characteristic masses of 0.3 and 7 pg (recommended are 0.35 and 4 pg, respectively, for Cd and Cu), respectively. The best condition for lead was using a non-modifier, with a characteristic mass of 6.9 pg (recommended is 10 pg). The limits of detection and mean recoveries, done over three consecutive days for aluminum, copper, lead, and cadmium, were 1.9, 2.9, 0.8, and 0.6 pg and 105, 104, 101, and 102 %, respectively. From the observed results, we may conclude that some metals, such as Al, Cd, Cu, and Pb, can be determined easily with graphite furnace atomic absorption spectrometry without sample digestion using a dilute nitric acid solution.