I found this post and it was exactly what I was looking for so I figured I would copy and paste it. He never got a reply so I was looking to see if I could get some answers.

FYI: since I have to take supervised tests from time to time and many of my friends drink and toke, it's often hard to find someone to give me a clean specimen. I can catch some of them at the right time and I would like to get a friend to just give me a large amount to keep on freeze so that each time I need it, I won't have to go through the trouble of tracking one down.

if i have a friend urinate for me the evening before the test, do i have to freeze it right away or something?

also, i get randomly drug tested at school so until i'm clean i plan on using the substitution method in case i get tested. the only thing i have to worry about is whether or not the age of the urine can be detected, and the exact temperature i need to keep it at.

any help would be appreciated, thanks a ton