Ahh yes, the ole substitute a clean sample trick. My favorite. Substitution guidelines are linked to in my signature. Human urine should ALWAYS be kept in an air tight, leak proof container. It will keep at room/body temp for up to 8 hours, refrigerated up to 30 days and frozen up to 1 year. Personally, my clean pee goes directly into the freezer. Thaw and warm it with warm water to the 100-105 range, crotch it and your ready for the piss nazi's. Crotched properly, it will maintain a temp of 96 all day, but you need to practice this at home with a 2oz bottle of water. After you are comphy keeping the temp in the acceptable range, 90-100, with your practice bottle, your ready to go with your 2oz of clean urine for the test. Best of all, you don't have to quit smoking. Believe me, it's really pretty simple. I've done it dozens of times.
Hope that helps.
:!)
N2