Masking (chemistry)
In chemistry, masking refers to the obscuring of one substance by a second substance. In order, for example, in qualitative inorganic analysis to prevent the detection of a certain ion from being interfered with by another ion, a masking agent is added which reacts with the interfering ion. This is often done by forming a stable complex with the interfering ion. For example, the detection of cobalt (II) with thiocyanate is disrupted by iron (III), since the latter with thiocyanate gives an intense red color which can mask the blue color of the cobalt thiocyanate. By adding fluoride , the iron ions are converted into the stable, colorless fluorido complex, which no longer reacts with thiocyanate.
The masking of interfering ions is also used in quantitative analysis. For example, in the complexometric titration of zinc ions in the presence of iron (III), the iron ions can be complexed with triethanolamine so that only zinc is detected; the iron-triethanolamine complex is too stable to react with the titrant EDTA .
Individual evidence
- ↑ Entry on masking. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
- ↑ Jander-Blasius, Textbook of analytical and preparative inorganic chemistry, 8th edition, S. Hirzel Verlag, 1969.
- ↑ Complexometric determination methods with Titriplex (R), E. Merck, Darmstadt, 1975.