Quantification of the Rubidium in Beverage Products Micro Samples by Platinum-wire Loop in Flame Atomization Atomic Emission Spectrometry

The rubidium content in 3 μL of some beverage products (beer, wine, vegetable and fruit juices) atomized from a Pt-wire in the methane-air flame has been determined by atomic emission spectrometry. The flame atomization conditions of rubidium were optimized, they are: λ = 780.0 nm, the height of 8 mm over the burner head, gas flow rates of 300 L h -1 air and 34 L h -1 methane. The effect of Na, K, Cs, Sr and acetone on the emission of rubidium was studied too. The limit of quantification (6σ) obtained is of 4.3±1.8 pg in the presence of 50 mg L -1 K and 5% v/v acetone (P = 0.05). The rubidium content of the samples has been determined with continuous nebulization and by atomization from the Pt-wire, using the standard calibration curve and the standard addition method. The results of the two procedures agree within the determination errors.