Flame-heated tubes are widespread in flame-AAS, mainly for the determination of hydride-forming elements. Instead of the introduction
of gaseous compounds liquids can also be introduced continuously in such an absorption cell. With the aid of an HPLC pump
the liquid is forced through a very fine nozzle, generating an aerosol beam less than 0.5 mm in diameter. This beam travels
a distance of 10 cm as a “free-flying aerosol jet” into the sample introduction hole of a metal tube furnace placed in the
flame. Both introduction of the entire sample and the long residence time lead to a considerable improvement in power of detection.
The detection limit for 100 μL samples amounts to 7 μg/L (Pb) and to 0. 2 μg/L (Cd), which means an increase in power of detection
of between one and two orders of magnitude compared to conventional flame-AAS. The relative standard deviation (100 μL sample
volume, N = 10) was found to be 1.3% (signal area) for 600 μg/L Pb and to be 1.5% (signal-area) for 15 μg/L Cd. RSD values
from measurements in peak-height amounted to 2.2% (Pb) and to 1.7% (Cd).
Received: 21 June 2000 / Revised: 4 August 2000 / Accepted: 5 August 2000