Masking effects for Mo, Re, Pd and Ru by S and N-donor reagents through MIDOA and NTAamide extraction

Sasaki, Yuji  ; Morita, Keisuke ; Shimazaki, Shoma*; Tsubata, Yasuhiro   ; Ozawa, Masaki*

We examined the masking effects of 16 water-miscible reagents, on the extraction of Mo, Re, Ru, and Pd. The extractants, methylimino-dioctylacetamide (MIDOA) and hexaoctyl-nitrilotriacetamide (NTAamide(C8)), show significantly high distribution ratios for these metals, were employed in this study. Masking effects were observed as a decrease of distribution ratio with an increase of masking agent concentration in these extraction systems. The results showed that Pd and Ru can be masked by similar reagents including N- or S- donor atoms, which suppressed the extraction into the organic phase. In contrast, distribution ratio of Mo was only slightly masked by the above mentioned reagents. The masking of Mo was achieved using complexing agents having a central N(CHC(P)=O) framework that is important for this purpose. A masking agent for Re was not found in this study.