Flow-injection thermospray sample deposition for electrothermal atomization-atomic absorption spectrometry

Abstract

A flow-injection system has been used successfully for thermospray sample deposition in electrothermal atomization-atomic absorption spectrometry (ETA-AAS). Under optimized conditions, i.e. for a sample flow-rate of 0.7 ml min , a thermospray vaporizer temperature of 300°C and a deposition temperature of the graphite furnace of 120°C, the sensitivity is equal to conventional ETA-AAS. At deposition temperatures higher than 120°C the sensitivity is slightly reduced, whereas above 170°C the sensitivity decreases rapidly. Tubes of graphite, pyrolytically coated graphite, totally pyrolytic graphite and glassy carbon behave similarly with respect to the temperature dependence of the thermospray sample deposition efficiency. Under the conditions stated a 10μl sample can be transferred in a few seconds, but much larger volumes (up to 500 μl in 2 mins) can also be introduced with a corresponding gain in sensitivity. The flow-injection thermospray deposition system can thus be used to cover a wide concentration range in ETA-AAS. With the thermospray vaporizer, sodium chloride concentrations up to 2% have been introduced into the furnace without clogging the fused silica capillary. Preliminary results indicate that thermospray deposition on a L'vov platform is feasible.