If you are being referred for a drug test, you may have been given a code that looks something like "640sn SAP 50-50/2000." This can actually be quite useful, because it reveals quite a few details about the drug test.
First some corrections
We should probably point out that you may have typed a couple of things wrong. If you didn't, please ignore this part. Firstly, the 640sn part should be 6405n (you mistook the "5" for an "S"). The first "50" should also be "5" (you'll see why later).
Breaking down the 640sn SAP 50-50/2000 code
Working on the correct code (6405n SAP 5-50/2000), we can break it down to reveal details about the test.
The "6405n" is simply a designation used by the lab to identify a particular test. In itself, this means nothing, but if you were to google it, you would no doubt be able to find the remaining details. The remaining parts are where it gets interesting.
The "SAP" is merely an acronym for "Substance Abuse Panel," so no big surprises there. This just means you'll be tested for a basket of different drugs. The number 5 provides the detail that there will be five panels on your drug test. This corresponds to the standard SAMHSA-5 drug test, which tests for weed, coke, opiates, amphetamines, and PCP.
Note that many similar compounds may also show up. For example, meth and ecstasy are highly likely to trigger a positive on the amphetamines panel. Note that some prescription medications may contain one of these chemicals, so check any meds that you're currently taking.
Finally, the "50/2000" refers to the cutoff levels for THC and opiates. This means a concentration of THC greater than 50ng/ml (2,000ng/ml for opiates) in your urine will result in a positive.
Is 640sn SAP 50-50/2000 a screening?
Yes, it is. You'll first be tested with a simple EMIT device. If you test positive for anything on this device, your urine will be further tested in the lab with a more accurate GC-MS process. Basically, if you pass the initial screening, you'll be safe. If you want to test yourself, you can buy similar home testing devices with the same panels and cutoffs.
How do you avoid failing?
If you've tested yourself and fail for something, or if you just know you might fail, don't worry. You can still pass the screening by consuming a detox drink on the day of your test. After using it an hour or two before your test, it quickly starts flushing your urinary system clean of toxins.
Even if you would normally fail a drug test, this process reduces the concentration of drug metabolites in your urine, so they will be under the cutoff level by the time you give your sample. Drug screenings are a simple positive/negative affair, so anything under the cutoff results in a pass.
This effect will wear off after a few hours, so make sure you get your timing right. Note that you can also get detox pills if you prefer.