ANALYSIS OF ORGANIC-COMPOUNDS BY PARTICLE-BEAM HOLLOW-CATHODE ATOMIC-EMISSION SPECTROSCOPY - DETERMINATIONS OF CARBON AND HYDROGEN IN AMINO-ACIDS

A detailed evaluation of the analytical characteristics of a particle beam/hollow cathode glow discharge atomic emission spectroscopy (PB/HC -AES) system is described for applications in the area of organic samp le analysis, The optimization of sample introduction, nebulization par ameters, and glow discharge conditions was performed for the elemental analysis (focusing on C and H) of a group of amino acids, By use of a high-efficiency thermoconcentric nebulizer, analyte particles are int roduced into a heated hollow cathode glow discharge source, in either now injection or continuous-now mode, for subsequent vaporization/atom ization and excitation. Nebulization temperature, solvent composition, and liquid now rate were studied to elucidate their roles in the ulti mate analyte emission characteristics for organic compound analysis. T he hollow cathode operating discharge current and gas pressure were op timized, with the general responses found to be similar to those for t he case of metal analysis. Background interferences from solvent and a dditive media on carbon and hydrogen determinations were studied and s ubstantially reduced, The analytical response curves for carbon and hy drogen present in amino acids were obtained using 200 mu L injection v olumes, showing less than 10% RSD for replicate injections over a conc entration range of 10-250 ppm, with detection limits of 3 and 1 ppm, r espectively, for C (I) and H (I) emission, Subsequent studies of the r esponse of carbon and hydrogen emission signal intensities to differen ces in amino acid stoichiometries suggest a capability of the PB/HC-AE S system for the determination of empirical formulas based on H (I)/C (I) intensity ratios.