As far as I understand:
- In is a preposition;
- La is an article;
- Nella is an articulated preposition, which is formed by the combination of in and la.
That being said, as I was writing a text, I was unsure of whether I should use
È necessario prenderlo in mano in cancelleria?
È necessario prenderlo in mano nella cancelleria?
The second example seems more suitable to me, as I am further specifying the object (in this case, chancellery) with the use of a definite article. Nevertheless, I am not sure about it.
Is in or nella more usual in this context? Or can I use either?