Can anybody explain what exactly is masking agent?

and if we add a masking agent in an unknown solution,how do we remove masked ion from the solution?Can anybody explain what exactly is masking agent?
Lancenigo di Villorba (TV), Italy





The question treating about ';Masking Agents'; belongs to Complex Themes.





COMPLEX


You have to remember that in a solution several ions, e.g. usually positive ions or cations derived from metals, may interact against several other chemicals.


These latters may result organized moleculae so their structures are able to fold themselves so they envelope around the metalic ions.


In this way, the organized moleculae may form stable ligands with the ion : a new object appears and it is a COMPLEX starting from its complicated feature.


Later their discoveries, complex shown different characteristics :


-) some complex involve metalic ions and solvent itself, so several metal's salts get hue to its own solutions (e.g. Cobalt(II), Nickel(II) or Copper(II) salts) ;


-) some complex are characterized by strong and recordable appearances, so they belong to Lab's Essays (e.g. Tetra-Amine-Copper(II) complex) ;


-) some complex given't any signs meanwhile they form strong bonds : surely you cannot involve it directly in analyte's detection (e.g. EDTA salts need for auxiliary chemicals).


So, Masking agents belong to latter type : e.g. Tartaric Acid may hide Copper(II) ions which precipitate not meanwhile you should add Sodium Carbonate.





MASKED ION BREAKING


To subtract the hidden ion from the ';Masking Agent';, you may treat it by means of hot solution of Sulphuric Acid, e.g. a strong acid. This suggestion starts from the nature of the Masking Agents which result usually Organic Weak Acids.


Sulphuric Acid should restore the undissociated Organic Acid so the hidden ion returns to detectable form.





I hope this helps you.