SUPERCRITICAL CARBON-DIOXIDE AS A CARRIER FOR SAMPLE INTRODUCTION IN ATOMIC-ABSORPTION SPECTROMETRY

The use of a supercritical carbon dioxide carrier to transport organic solutions of metal complexes to a heated restrictor is demonstrated as a means of aerosol or vapour generation for sample introduction in flame atomic absorption spectrometry. Calibrations obtained using conventional pneumatic nebulisation of continuously aspirated solutions or using flow injection into a water carrier are compared with those obtained using the carbon dioxide carrier. Injection of solutions of copper pyrrolidinedithiocarbamate in 4-methyl pentan-2-one into a carbon dioxide carrier at 1000 p.s.i. was shown to be 1.2 times more sensitive than injection of the same solutions into a water carrier with conventional nebulisation. The sensitivity of continuous nebulisation of the solutions, however, was not achieved. Dissolution of solid copper acetyl acetonate in supercritical carbon dioxide is demonstrated and subsequent vaporisation followed by atomisation in a heated quartz furnace is shown to occur.