Looking on the internet deeply has found these results:

Interested in it is the most popular phrase on the web.

Interested on it 1354,000 results on the web	Interested in it 136,800,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	I just remember that your father, he was very interested in it. And more importantly, why would Laila be so interested in it? Mr President, ladies and gentlemen, the people of Europe ask, when foreign policy is being debated, why they should be interested in it. Perhaps a few of you ladies might be interested in it. I'm glad you're interested in it. So why is Bryan interested in it? You think people would be interested in it? Actually, no, but the A.D.A. is interested in it.

Interested on it

1354,000 results on the web

Interested in it

136,800,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

I just remember that your father, he was very interested in it.
And more importantly, why would Laila be so interested in it?
Mr President, ladies and gentlemen, the people of Europe ask, when foreign policy is being debated, why they should be interested in it.
Perhaps a few of you ladies might be interested in it.
I'm glad you're interested in it.
So why is Bryan interested in it?
You think people would be interested in it?
Actually, no, but the A.D.A. is interested in it.