New masking procedure for selective complexometric determination of copper(II)

Area of Science:

• Analytical Chemistry
• Inorganic Chemistry

Background:

• Complexometric titrations are widely used for metal ion quantification.
• Accurate determination of copper(II) can be challenging due to interference from other metal ions.

Purpose of the Study:

• To develop a highly selective masking procedure for the complexometric determination of copper(II).
• To investigate the efficacy of ternary masking mixtures for copper(II) analysis.

Main Methods:

• A new masking procedure based on the decomposition of the copper-EDTA complex at pH 5-6.
• Utilized ternary masking mixtures containing thiourea, ascorbic acid, and thiosemicarbazide (or phenanthroline/dipyridyl).
• Employed back-titration of excess EDTA with lead or zinc nitrate using Xylenol Orange indicator.

Main Results:

• The developed masking procedure demonstrated high selectivity for copper(II).
• The method effectively masked interfering cations including Ag(+), Hg(2+), Pb(2+), Ni(2+), Bi(3+), As(3+), Al(3+), Sb(3+), Sn(4+), Cd(2+), Co(2+), Cr(3+), Fe(3+), and Mn(2+).
• Consecutive determination of Hg(2+) and Cu(2+) was successfully achieved in the presence of other cations.

Conclusions:

• The new masking procedure offers a reliable and selective method for copper(II) determination.
• This technique simplifies the analysis of copper in complex matrices.
• The ability to perform consecutive determinations of Hg(2+) and Cu(2+) is a significant advancement.