PARTICLE-BEAM AQUEOUS SAMPLE INTRODUCTION FOR HALLOW CATHODE ATOMIC-EMISSION SPECTROSCOPY

The design and preliminary operating characteristics of a particle bea m/hollow cathode atomic emission spectrometry (PB/HC-AES) device is de scribed. By use of a high-efficiency thermal-concentric nebulization s ystem coupled to a particle beam LC/MS interface, analyte particles or iginating in aqueous solution are introduced into a heated hollow cath ode glow discharge for subsequent vaporization and excitation. The The rmabeam (Extrel Corp.) interface permits liquid introduction in either flow injection or chromatographic mode. Helium and argon are evaluate d as discharge gases over a range of pressures and discharge currents, with He chosen as the most appropriate for subsequent analytical stud ies. Nebulization temperature, liquid (solvent) flow rate, and vaporiz ation temperature are evaluated in order to determine their effects on analyte emission characteristics. Optimized sample introduction and H e plasma operation conditions are employed to study the analytical cha racteristics of the PB/HC-AES system. Background equivalent concentrat ions (BECs) for Na and Cs (as nitrates) in aqueous solutions are 0.53 and 0.74 ppm, respectively. Subsequent studies of cesium at ppm levels in diluted (1000x) simulated nuclear waste solutions (5.0 M NaNO3 and 0.1 M KOH) indicated that the addition of excess chloride as a counte rion, rather than nitrate, greatly enhances detectability. BEC values for Cs in aqueous solution were lowered by a factor of similar to 10, while for the diluted simulant the values were lowered by >100X, with detection limits in the latter found to be similar to 8 ppb.