My friend had a lot to drink for 5 or six days straight, but quit drinking at about 10 on Sunday night, and is taking the 80 hour test on Thursday at 3 pm. That's 90 hours; what's the chance of her being positive.

Are "we" clear? Do you have the same situation?

What is "a lot" to drink?

It varies but, yes, 90 hours without a drink, yes, your friend should pass.

Judy is probably right, with emphasis on "varies" and "should pass".

The closest study relating to heavy alcohol consumption, Borucki 2005 (http://www.ncbi.nlm.nih.gov/pubmed/15897723?dopt=Abstract), would put your chances at 82% based on 90 hours.

But, the time doesn't begin at last drink. Rather, when you reach 0-BAC. So the important factor in determining clearance time for EtG is BAC at time of last drink. You then estimate alcohol clearance and subtract that from the 90 hours.

Given the drinking pattern you describe, alcohol metabolism is probably comparatively rapid. If metabolism didn't take longer than 12 hours then you should fall within the 82%. (That is only an average based on a small group)

In summary, the time of EtG elimination is dependent first on the amount of EtG present.

I would be very surprised if she doesn't pass, but if she has health issues (liver issues) she could test positive. As Judy wrote earlier, if you define "a lot", especially for the last day of drinking, a better answer may be available. Also, a 500 cutoff would almost assure her passing.