elastic net ( linear model expert)

The data set is currenlty divided into lipids, cmpds(compounds) and proteins.Protein data gathering I am doing and will provide once done.These are all compounds found in our blood. So basically we want to predict their true concentration from LCMS machine.Right now if you see problem discussed we are in Step 4. We have included chemical variation and instrument variation(see ppt for more clarity). For lipids and cmpds(compounds)I am getting R square 75% and 69% and MAE 0.4 and 0.8 . I want to improve these metrics so as to increase accuracy by using best linear model. Can you help me in that? I have attached dataset and model I created