Dibromocarboxyarsenazo (DBCA) was used to complex Fe and Cu ions at pH 6.22, and complexes Cu(DBCA) and Fe(DBCA) were formed. Fe ion replaced Cu competitively from its dinuclear complex Cu(DBCA)Cu to form the heterodinuclear complex, Cu(DBCA)Fe. The light-absorption ratio variation approach has been applied to the direct determination of Fe ions with a high selectivity and good sensitivity using heterodinuclear replacement complexation. The limit of detection of Fe is only 2.5 ng/mL. The results from the analyses of five Huangpu River (Shanghai) cross-section samples indicate that Fe ions are from 5.0 to 39.2 μg/L with the recovery rates between 85.5 and 111.5%.
- Determination of iron ions
- Heterodinuclear replacement complexation
- Light-absorption ratio variation approach
- Spectral correction technique
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