Electro thermal atomic absorption (ETAAS; GFAAS) the technique involves introducing a small amount of sample and then resistively heating a tube of graphite, which becomes the atom cell. Due to the nature of the heating mechanism the accuracy of the results are inherently increased. The tube temperature is controlled by computer input and can have a consistent temperature profile from sample to sample and from standard to sample. This element of control increases the repeatability of the method. Samples are generally entered as dilute aqueous solutions in 20-50 uL quantities.

The use of chemical modification shoud be considered if an analyte is highly volatile or if analyte and matrix volatilize at similar temperatures. The modification will allow ashing at higher (or atomization at lower) furnace temperatures, getting rid of the matrix without loosing a relatively volatile analyte (or atomizing the analyte without the matrix). Several compounds are known in the literature for this application, the most common ones are magnesium and palladium solutions. You can choose your matrix and analyte modifier from C.P.A. catalogue as well as Quality Control standard solutions for GFAAS and AAS-VGA.