Flow injection semi-online sorbent extraction preconcentration for graphite furnace atomic absorption spectrometry

A micro-flow injection sorbent extraction preconcentration system was combined 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 used as a sorbent in a 15-mu L conical microcolumn. The metals to be determined 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 ethanol. 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 obtained 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 trace 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.