Can i take the fitness supplement l glutamine as part of my gym diet without any contradiction to my 150mg dose of the antidepressant sertraline??

Yes: Glutamine is an amino acid, a building block of protein. Because of this, some believe it helps repair and build muscle, but there is little evidence it actually improves athletic performance. Glutamine interacts with some cancer chemotherapy and seizure medications but sertraline seems to be ok. I don't know that it would be of benefit for you to take, but I doubt it is harmful. Good wishes:)