Determination of Cu, Zn, Mn, and Pb by microcolumn packed with multiwalled carbon nanotubes on-line coupled with flame atomic absorption spectrometry

Modified multiwalled carbon nanotubes (MWCNTs) were used as a packing material for flow injection on-line microcolumn preconcentration of trace amounts of the metal ions of Cu, Zn, Mn and Pb, and subsequent flame atomic absorption spectrometry (FAAS) in one run after desorbing the ions with hydrochloric acid and injecting them into the nebulizer of an FAAS. Parameters such as loading time, flow rate, pH, eluent concentration, and flow rate were optimized. Enrichment factors are 20.3, 14.2, 20.6 and 15.4 respectively, and the sample throughput is 25 h(-1). The limits of detection (three times the standard deviation of the blank) are 0.59, 0.62, 0.28 and 1.00 A mu g L-1, respectively, and standard deviations range from 2.6 to 4.6% (n = 7). The method was applied to the analysis of these ions in vegetables, and accuracy assessed via recovery experiments.