FLOW SYSTEM FOR LIQUID SAMPLE INTRODUCTION IN ARC SPARK EXCITATION SOURCES/

A flow system based on the monosegmented flow analysis (MSFA) approach is described for delivery of liquid samples to arc/spark excitation s ources commonly used in spectrographs. A Carl Zeiss PGS-2 spectrograph , previously-automated in the laboratory by replacing its photographic plate detection system with a photodiode array, was employed, The sam ple is introduced via an injection port into the path to the excitatio n source, where the liquid sample plug (typically 50 mu l) is passed t hrough a hole drilled in a conventional graphite electrode, The arc/sp ark is applied to excite the sample for a computer-controlled time int erval and the light emitted is integrated, After sample measurement, t he electrode is cleaned by applying the arc/spark while the mater stre am, that follow the sample plug, is being pumped, About 25 samples can be analysed per hour, The flow system was evaluated for determination of aluminium (3-50 mg l(-1)), lead (5-160 mg l(-1)) and mixtures of h afnium (60-120 mg l(-1)) and zirconium (600-1300 mg l(-1)).