AEROSOL DESOLVATION STUDIES WITH A THERMOSPRAY NEBULIZER COUPLED TO INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

TWO desolvation systems commonly used in ICP-AES have been evaluated w hen coupled to a thermospray nebulizer, The desolvation systems are: ( i) a thermostated spray chamber (TSC) and, (ii) a two-unit desolvation system (TUDS) in which the first unit is a heated single-pass spray c hamber and the second one is a Liebig condenser. Both systems were eva luated with aqueous and organic solutions. The temperature of the cham ber in the TSC (-5 to 20 degrees C) and the temperatures of the heated spray chamber (60 to 140 degrees C) and the condenser (-5 to 20 degre es C) in the TUDS were taken as variables. To e evaluate the effect of these variables on the performance of the desolvation systems, drop s ize distribution of the tertiary aerosol, solvent and analyte transpor t rates and emission signal have been measured. Under optimal desolvat ion conditions, the values of the solvent transport efficiencies were similar for both systems, ranging from 2.3 to 9.5%. Analyte transport efficiency values ranged from 36 to 77% and from 5 to 8% for TUDS and TSC, respectively. TUDS gives rise to higher signals (6 to 7 fold high er) and lower LOD (2 to 11 times lower) than TSC, As regards the solve nt nature, the highest emission intensity and lower LOD are obtained w ith ethanol, followed by water and butan-1-ol, The LOD values obtained with the combination thermospray-TUDS are 2 to 26 times lower than th ose obtained with a conventional pneumatic nebulizer coupled to the sa me desolvation system.