I have been using Quick Fix for five years and have used Agent X once. Both have always been successful. I saw this post and figured I could help others searching for help by adding a few pointers.

If you are having the "swooshing bottle" problem as the post above, do not add water. Open the bottle and gently squeeze a little air out and tighten the cap. No air = No swooshing.

If you are using Quick Fix (2oz.), be aware that 2oz. is the exact amount needed by the lab. And the lab is also aware that Quick Fix is 2oz. The collector might be trained to ask for more than the line on the cup. This is a way to catch you. Or they can wait for you to come out, and say "Oh, two ounces exactly?" and dump it and ask for more. If you are in the position to afford TWO bottles of quick fix, I recommend it. Agent X is 3oz., which gives you a little more to use than quick fix.

The only time a collector has really thought twice was when I had the bottle TOO HOT. It was winter and I went too heavy on the car heater, and when I turned in the sample the strip was maxed out and he gave it a good long look before I awkwardly asked him if they were getting ready to close. Be sure your bottle is hot, but dont go overboard.

If you are going to use this product, relax. Buy from a trustworthy shop, make sure it is a recent batch ( and not expired), and as long as your temp is in range you will be fine.

And if anyone didn't know, this test only works on split specimen tests (2 tubes) and NOT on the cheaper test strips.

Smoke on.