Just to give you an idea of the power of Palo azul. I brewed one bag of probably a palmful or two of the herb into 1 gal of water and let remain at room temp to be absorbed by the body quicker after boiling. Strain out the herb, you're making a tea basically. Boil fairly rapidly for 15 min.
I smoked less than 12 hours to a drug test. I drank the whole gallon the morning of starting about 5 hours prior to the test. I drank it all the way up until leaving to the testing center.
I was frankly pretty surprised I passed, but I did. They also did a test because my pee was so clear. It passed the test checking to see if the sample was altered or the person flushed their system with water before.
I believe all the nutrients replace chemicals that should be in your pee so it doesbt appear as if you just did a flush or mask, but I could be wrong. Just a guess.
You can buy it online and its pretty cheap. Just search buy Palo azul on Google, that's what I did.
It might be too late that I'm responding to you, but hopefully others will come across this and pass their test. Just try to buy the herb two weeks prior to a test to make sure it arrives in time. I always just keep a couple extra bags on hand for randoms, that way I'm always prepared.
P.s. - some say the herb can be saved and used for future teas but I'm certain this degrades the potency of the drink. I would avoid doing this and playing it on the safe side, especially for the price. $10 extra is definitely better than failing a test in most cases.
Good luck, and be safe!