Optimization of hydride generation methods for AAS

Every hydride generator can be characterized by outlet flows of hydride molecules and carrier gas which are reflected in the atomizer as an absorbance value. Expressions relating the two outlet flows for currently used hydride generation methods to generation parameters (apparatus dimensions, reagent concentrations, flows) are derived. A general assessment of hydride generation methods based on these expressions shows that pressure collection is inferior to the other generation methods in all respects. Both direct transfer methods (batch and continuous flow) are equal from the standpoint of sensitivity but continuous flow is more advantageous, mainly because of its independence of the kinetics of hydride evolution which results in a better accuracy. Cold trap collection methods are more labourious and more time consuming but they promise a superior sensitivity.