DETERMINATION OF PLATINUM IN BIOTIC AND ENVIRONMENTAL-SAMPLES BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY AFTER ITS ELECTRODEPOSITION INTO A GRAPHITE TUBE PACKED WITH RETICULATED VITREOUS CARBON

Summary. Tobacco, beans, slag and dust samples were digested with nitric and hydrochloric acids in high-pressure PTFE bombs. Pt in the sample solutions was electrochemically deposited at -0.9 to -1.2 V in a flow system incorporating a 3-electrode flow-through cell with a graphite counter and Ag/AgCl reference electrodes. A pyrolytically coated graphite tube packed with reticulated vitreous carbon (RVC) served as the working electrode with the RVC filling axially bored to let the light beam pass through the tube during the AAS measurements. This opening was plugged with a glass rod during the preconcentration step. After the electrodeposition the tube was placed into the graphite furnace and an atomization temperature of 2700-degrees-C was applied. The geometry of the cell, flow rate for electrodeposition, deposition potential and electrolyte composition were optimized. The absolute detection limit was found to be about 0.3 ng Pt.