Determination of Cd and Pb at mu g/L levels by HHPN-beam injection flame furnace-AAs

Flame-heated tubes are widespread in flame-AAS, mainly for the determinatio n of hydride-forming elements. Instead of the introduction of gaseous compo unds 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 noz zle, generating an aerosol beam less than 0.5 mm in diameter. This beam tra vels a distance of 10 cm as a "free-flying aerosol jet" into the sample int roduction hole of a metal tube furnace placed in the flame. Both introducti on of the entire sample and the long residence time lead to a considerable improvement in power of detection. The detection limit for 100 muL samples amounts to 7 mug/L (Pb) and to 0.2 mug/L (Cd), which means an increase in p ower of detection of between one and two orders of magnitude compared to co nventional flame-AAS. The relative standard deviation (100 CLL sample volum e, N = 10) was found to be 1.3% (signal area) for 600 mug/L Pb and to be 1. 5% (signal-area) for 15 mug/L Cd. RSD values from measurements in peak-heig ht amounted to 2.2% (Pb) and to 1.7% (Cd).