The right-back has been reported to be on the verge of agreeing a deal with Real Madrid.
As the defender is out of contract in the summer, he can talk to clubs outside England from January 1st.
On players agreeing such deals, Slot stated: “I think I have a lot of control over what they do if they are on the training pitch or if they are in a meeting with me, but talking about their private lives, I don't have control about them.
“That was the situation I had a year ago, it's been the situation for as long as I've been a manager, but I have control to a certain extent over them from what I expect from them on the pitch. I am really pleased to see what Virgil (van Dijk) brings, what Trent brings and what Mo brings.
“The positive thing for me is that for four or five months it was only Trent, Mo and Virgil you guys were talking about and I assume - don't let me down, please - that people now are going to talk about every player we are going to bring in in the upcoming month and which other players are going to leave, so I guess a lot of questions as well, not only about these three.”
On any incoming signings in January, he added: “There's nothing in the media yet about who we're going to bring in? And also not in my mind. I’m very happy with the squad we have. I said this six months ago and everybody said, 'Is this guy crazy?' but I think the players showed the confidence the club and me as well had in them was well deserved. If you look at Jarell Quansah today, (he) hasn't played a lot until now. A few appearances.
“The way he played today shows also that is (the case) - that we keep working with these players because we're going to need all of them at a certain moment. Today Jarell played a very good game for us.”