(5,5'-Dicarboxy-biphenyl-2,2'-dicarboxyl-ato-κO,O)bis-(1,10-phenanthroline-κN,N')zinc(II) dihydrate.

In the title compound, [Zn(C(16)H(8)O(8))(C(12)H(8)N(2))(2)]·2H(2)O, the Zn(II) atom is located on a twofold rotation axis and is six-coordinated by two O atoms from a 5,5'-dicarboxy-biphenyl-2,2'-dicarboxyl-ate ligand and four N atoms from two 1,10-phenanthroline mol-ecules in a distorted octa-hedral geometry. The crystal structure involves O-H⋯O hydrogen bonds.

[Simultaneous determination of trace amounts of iron(II), copper(I) and cobalt(II) in aloe by second derivative peak area spectrophotometry].

A new method for simultaneous determination of iron(II), copper(I) and cobalt(II) was established by second derivative peak area spectrophotometry in chromogenic system of 1,10-phenanthroline. The method could avoid disturbing by some ions. The accuracy and sensitivity were improved. There is a linear relationship in the range of 0.0-8.5 microg x mL(-1) for Fe(II); of 0.0-7.3 microg x mL(-1) for Cu(I); and of 0.0-5.9 microg x mL(-1) for Co(II). The method has been applied to simultaneous determination of iron(II), copper(I) and cobalt(II) in aloe with satisfactory results. The average recovery is 98.6%-102% and the RSD is 0.1%-0.2%. There is no remarkable difference between these results and those of ICP-AES method.