Photometric determination of copper with N-(dithiocarboxy)sarcosine after preconcentration with amberlite xad-2 resin.
The copper(II) chelate of N-(dithiocarboxy)sarcosine (DTCS) is sorbed on a column of Amberlite XAD-2 resin from a pH-7 phosphate solution (0.1M) and stripped with a pH-9.0 ammonia solution (0.2M) in 60% methanol. The absorbance of the eluted chelate is measured at 432 nm against water. Sodium nitrilotriacetate, sodium tripolyphosphate, and EDTA can be used to mask interfering metal ions other than mercury(II), the resulting complexes not being sorbed on the resin. The mercury(II) chelate of DTCS is also sorbed on and stripped from the column along with the copper chelate, but does not interfere in the photometric determination of copper, because it is colourless. The recovery of copper(II) is quantitative from test solutions (50-500 ml) of any salinity up to that of sea-water. Concentration factors of up to about 20 are obtained. The method is highly selective for copper and can be applied to its determination in sea-water.
Sakai
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Faculty of Education, Miyazaki University, Funatsuka 1-1, Miyazaki-shi, Miyazaki, 880 Japan.