Group speciation of metal dithiocarbamates by sorption on C60 fullerene

A simple flow injection system for the on-line preconcentration of metal dithiocarbamates (fungicides) by sorption on a C-60 fullerene column was developed. Neither the acid hydrolysis needed by the conventional method to release CS2 nor derivatization is required as the fungicides are directly retained on the sorbent column and subsequently eluted from it with dilute HNO3. The eluted fraction is directly fed into a flame atomic absorption spectrometer. Group speciation can be done according to the metals present in the dithiocarbamate (viz., dithiocarbamates of Zn2+, Mn2+, or Fe3+) but no within-group discrimination is possible (ziram, zineb and propineb provide a global response). The analytical figures of merit of the proposed method are as follows: limits of detection (3 sigma) from 1 to 5 ng ml(-1); precision (RSD) ca. 2.5%; and preconcentration factor 45 (using 10 ml of sample). No interference from metals such as Zn, Mn or Fe, as inorganic salts, was observed. The method was applied to the resolution of synthetic mixtures as well as to the speciation/determination of ziram, maneb and ferbam in spiked grain samples, all with acceptable recoveries.