Abstract
A new method of dynamic three-phase microextraction (LLLME) combined with multi-element graphite furnance atomic absorption spectrometer (GFAAS) was proposed for the determination of trace Pb, Cu, and Zn in sea water. In a extraction step, three elements in 40 ml of sea water adjusted to basic condition (donor phase) were extracted into a organic film containing a chelating agent (dithizone) in o-xylene and then back-extracted into 10 μl of nitric acid solution (acceptor phase) for determination by GFAAS. Because the organic and acceptor phase were repeatedly moved in and out of the hollow fiber channel, the organic film is renewable, and the relative movement between the acceptor phase and the organic phase would enhance the enrichment factor. Under the optimized conditions, the detection limits were 9.0*10-3μg/l，1.9*10-1μg/l，4.8*10-2μg/l for lead, copper and zinc. The relative standard deviations (RSDs) were in the range of 10.1~19.5%. Two standard reference materials (CASS-4, NASS-5) were used to confirm the accuracy of the technique, however, the found values for most elements were not within 85~115% of certified values.