SEPARATION AND PRECONCENTRATION BY FLOW-INJECTION COUPLED TO TUNGSTENCOIL ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A flow injection system coupled to a tungsten coil electrothermal atom izer has been developed for on-line separation and preconcentration, u sing lead as a model element. The system utilizes three-way solenoid v alves for sampling, buffering, washing and reconditioning solution man agement, and the resin column is inserted in the tip of the autosample r arm of a Varian GTA-96. The solenoid valves and tungsten coil power supply were controlled by a computer program written in Visual Basic, interfaced with the built-in Varian software. The system performance w as tested by loading the resin column with the sample flowing at 3 ml min(-1) for 60 s. Elution was performed automatically by sampling 20 m u l of the eluent from a sample cup of the autosampler, and this aliqu ot was delivered into a 150 W tungsten coil. With Chelex-100 resin, th e separation of concomitants was tested with lead in the presence of a s much as 1000 mg l(-1) of Ca, Mg, Na or K. The model system presented an enrichment factor of 64 at a sampling rate of 30 samples per hour.