What are interfering radicals?

Hint: There are mainly two types of radicals, neutral radicals and charged radicals. In charged radicals, there is one cation radical with positive charge and one is anion radical with negative charge. Interfering radicals are also known as anion radicals.

Complete answer: Interfering radicals are those radicals which interfere in qualitative tests of salt analysis. Interfering radicals are also known as anion radicals.
Interfering radicals include tartrate, fluoride, oxalate, silicate, phosphate and borate. As the name suggests they interfere in the qualitative analysis of salts, thus they are unwanted.
They form complex compounds with third group reagents like ammonium chloride, due to this the precipitation of the third group remains incomplete. Thus they have to be removed before the reaction starts.
One or more interfering radicals might be present in the solution, they have to be removed in a particular order to dismiss the possibility of any change in the solution.
First, oxalate and tartrate are removed, then borate and fluoride are removed, after that silica is removed and at the last, phosphate is removed. This process has to be done in an order and not randomly to avoid any unwanted change in the solution.

Note:
These interfering radicals are also known as anion radicals which are also called acidic radicals. It has been given such a name as that radicals are particularly obtained from an acid. It is confusing because in this concept an acid is something which accepts electrons and is a cation. But, as this cation at the end will be derived from a base, it will be called a cation radical.