I have use just the heating pad the last two times I used qf and it worked fine. Both times I left the interview hired and with the drug test papers and drove a block away and put the heat pad on the bottle and tucked it away in my fruit of the looms then drove toward the testing site and about a block away I would pull over and check the temp and all was fine. About 45 minutes total. I did have 24 hours to take the test but I'm a little impatient and would want to get it over with. It wouldn't hurt to nuke it if you can. Good luck...:thumbsup: