A micro-flow injection sorbent extraction preconcentration system was combi
ned with a graphite furnace atomic absorption spectrometer. The combination
results in an integrated system for the determination of trace amounts of
heavy metals. Silica bonded with octadecyl functional groups (C-18) was use
d as a sorbent in a 15-mu L conical microcolumn. The metals to be determine
d were preconcentrated as diethyl dithiocarbamate chelates onto the column
for 60 s and then rinsed with deionized water and eluted with 40 mu L of et
hanol. Compared with direct injection of 40 mu L of aqueous sample solution
, enrichment factors of 30, 32, and 29 and detection limits (3 sigma) of 7.
8, 12.8, and 3.9 ng/L for cobalt, nickel, and lead, respectively, were obta
ined with 60-s sample loading at 3.0 mL/min for sorbent extraction, 40 mu L
of eluate injection, and peak area measurement. The results obtained for t
race amounts of cobalt, nickel, and lead in reference materials showed that
there were no significant differences between the certified and determined
values. (C) 1999 Academic Press.