Electrothermal graphite furnace atomic absorption signal for gold in organic matrices

The electrothermal atomic absorption signal for gold deposited after pyrolysis of organic matrices was investigated. The signal shape was altered by pyrolysis of a volatile organic matrix (methanol, propan-1-ol and pentane-1,5-diol) and also a nonvolatile matrix (ascorbic acid, glucose and sucrose), with a low-temperature shift of signal and the formation of a shoulder (peak) on the tail. Pyrolysis of the organic matrix produced two types of carbon residue (active carbon and a thermally stable carbon residue). The early shift occurred as a result of the formation of smaller microdroplets of Au by adsorption of the analyte on the active carbon. The latter shift resulted from the formation of larger sized microdroplets by admission, diffusion or transport of the analyte into the inside of the thermally stable carbon residue. These mechanisms were supported by kinetic investigations.