Sample preconcentration by continuous flow extraction with a flow injection atomic absorption detection system

Abstract

The flow manifold described allows automatic extraction of metal ions in aqueous samples into 4-methyl-2-penthanone with ammonium pyrrolidinedithiocarbamate as an extracting agent. The organic extract is led into the loop of an injector situated in an integrated feed system of an atomic absorption spectrometer. No dispersion of the injected organic extract plug, 110 μl, occurs in the aqueous feed stream and the resulting signal from the spectrometer is a peak. An increase in sensitivity of 15–20 is achieved for copper, nickel, lead and zinc in comparison with direct aspiration of the aqueous samples. The sampling frequency is 40 h −1 and the consumption of 4-methyl-2-pentanone is typically 0.3 ml min −1. The detection limit for copper is about 1 μ l −1.