Applycation of the synergistic extraction to separation analysis

研究了单硫代酰三氟丙酮（STTA=HR）和1,10-菲罗啉（phen）协同萃取Mn（II）和Fe（II）的机理，发现氯仿相的萃取物为MnR_2（phen）和FeR_2(phen)_2。该萃取体系适用于Fe（II）和Mn（II）的定量分离。phen的加入加速了STTA对Ni（II）的萃取，形成了Ni(phen)_<2+>和Ni(phen)_2^<2+>这两种不稳定物质。相反，Ni(phen)_3^<2+>对STTA阴离子具有惰性。如果Co(phen)_3^<2+>是不稳定的，则Co（II）可以优先被萃取，而Ni(phen)_3^<2+>则保留在水相中。在上述原理的基础上，采用双硫腙-phen体系对Co（IIr）和Ni（II）进行了定量分离，其中在水相中预先加入phen以保证Ni(phen)_3^<2+>的定量生成。最后，将协同萃取系统应用于痕量金属离子的富集。结果表明，采用双硫腙-氧化三烷基膦萃取体系和原子吸收光谱法可以测定天然河流水样中的痕量Cd（II）。

Synergistic extraction mechanism of Mn(II) and Fe(II) with monothiothenoyltrifluoroacetone(STTA=HR) and 1,10-phenanthroline(phen) was studied, and it was found that the extraction species in chloroform phase were MnR_2(phen) and FeR_2(phen)_2. This extraction system was shown to be applicable to the quantitative separation of Fe(II) from Mn(II).The extraction of Ni(II) with STTA was accelerated by the addition of phen due to the formation of labile species, Ni(phen)_<2+> and Ni(phen)_2^<2+>. In contrast, Ni(phen)_3^<2+> was found to be inert toward STTA anion. If Co(phen)_3^<2+> is labile, it is expected that Co(II) can be extracted preferentially while Ni(phen)_3^<2+> remains in the aqueous phase. On the bases of the above principle, the quantitative separation of Co(IIr from Ni(II) was performed by using dithizone-phen system,in which phen was added preliminarily in the aqueous phase to ensure the quantitative formation of Ni(phen)_3^<2+>.Finally, a synergistic extraction system was also applied to a method for the preconcentration of trace metal ions. As a result, a trace amount of Cd(II) in natural river water samples could be determined by employing dithizone and tributylphosphine oxide extraction system and atomic absorption spectrometry.