I am a little confused. So you said you smoked 8yrs ago. Does this mean you haven't smoked in 8years!? If so, then you shouldn't have a problem passing.
If you have smoked recently, your best bet is probably to find a head shop close by and see if they have some of the stuff that helps mask it for a few hrs. That stuff usually tastes like *** though.
I had to have a piss test last year and when I found out I had 5days to get clean or mask it. I was told by a family member to get this stuff called fruit pectin "sure gel" that they use for canning jelly's and stuff. You can find it at super walmart or any grocery store. He had worked on the railroad for 30+yrs and swore by the stuff.
I drank a shit ton of water for a few days and then got two packs of that stuff. I drank one the night before my test with a few glasses of water and then drank the second pack with only a couple glasses of water. This stuff tastes like lemonade with no sugar. Not real easy to get down.
I passed the test but I do not know if it was the fruit pectin, all the water, or the fact that I only weigh about 140 and have a really fast metabolism. Probably a mix of all.
GL