I had to do a 24 hour urine collection test this past week for one of my doctors. I ended up having to do it twice because the first time I used a regular tupperware food container since my doctor never gave/ didn't tell me I needed a special container. The container I used the second time had a special acid in it (at least that's what the technician who gave it to me said) to help preserve the urine. I don't know if urine used in a drug test needs to be preserved as I've never had one, but it might be something to look into. Wouldn't that suck to get caught using old urine.