GC/MS Drug Testing Question

[a1d123]

I am new to the site so I am not sure if this topic has been discussed yet but my question focuses on the GC/MS confirmatory test which is usually given after a positive preliminary immunoassay test.

My job requires that all of our employees succumb to random drug testing so I am very careful not to indulge too much in something, although, I do dable. I like to occasionally take mushrooms on the weekend with friends. I've read that it is very uncommon to get tested for psilocybin on drug tests especially since I know my workplace uses a lab to test with a 9 panel drug test which doesn't test for psilocybin. I take seroquel at night to help me sleep which I do have a prescription for but I have read that seroquel can cause a false positive for methadone.

I know methadone is on the 9 panel so my dilemma is that I am scared to test falsely for methadone and when the GC/MS confirmation test is given to confirm that it is my legal seroquel medication, that they will also see the psilocybin.

When the GC/MS is done for the methadone check, will they see the psilocybin or do they have to be specifically looking for it?

Does GC/MS show everything in you whether it's tested for or not?

If my company doesn't elect to test for psilocybin specifically, will the lab inform them if it comes up or will they not do so based on the fact that it is not on a list of substances to test for by the company?

I would hate to pass the test for something legal and fail for something they weren't looking for in the beginning.

Any insight would be greatly appreciated.

Reputation Comments on this post:

First post and all, but go read the rules - don't incriminate yourself!

[Ilsa]

if my cat remembers correctly, gc/ms tests for one specific compound in an unknown (swiy's ) sample against the known structure of the compund being tested for, in this case, methadone. to test for psilocybin, the sample would have to be tested against a known sample of psilocybin, ehich they wouldn't be looking for, so overall, swiy is probably inthe clear.


better to be on the safe side and refrain from indulging for a month before if possible, if not, then as long as possible. read up on whether it's a fat or water soluble compound as the former taked a long time to leave the body (think thc) while the latter takes much less time (think cocaine).

hope this helps

here's another thread, not quite the answer swiy might need, but informative: http://www.drugs-forum.com/forum/sho...hlight=gc%2Fms

[Burnt]

GC-MS can detect more then one compound at once. It really depends what they are looking for though. If they see a weird signal they may investigate it. If they only look for a select few signals like opiates cannabinoids or stimulants then they won't notice SWIM routinely uses GC-MS to ID upwards of 50 compounds at a time in mixtures in the real world. The methodology is very sophistifated these days.

However concerning psilocin its not in your blood long so as long as you have a few days between using and a test its not a big deal. About your other substance you take if you get a positive result just explain you are on medicine or tell them before they do the test so they know.

[Methclinic]

They are just going to use the Gas Chromotography Mass Spectomatry for a positive comformation.Meaning if you came up positive for something in the paliminary test.Then they will use the GCMS test to confirm it because we all know that the Gas test doesnt have any room for error.Also they only use the Gas test to confirm the chemical in question.Meaning if you tested positive for Methadone then thats what there gonna look for.It wouldnt be cost effective or even worth it financily to use the GCMS test everytime.Even though they are alot cheaper than what they used to be lets say 4 years ago(then they were $500 a TEST!)Thats why they use the strip testers first and then the Gas test if theres a urine sample that flags an early positive.SwiMC isnt trying to claim high ground but he gets alot of his 411 from his sister whom has been working in one of the bigger testing labs in the US for the last 8 years

[Ilsa]

thanks for the input, my cat is a bit fuzzy on the details of gc/ms

[electrolingus]

Just wanted to add that GC/MS can detect many metabolites down to the picogram with 99.9% accuracy. Most positives from EMIT II assay(the most common method of urine drug testing) are rechecked by GC/MS. Modern GC/MS false positives are often caused by contamination during the preparation of the sample before it is ran. This is rare, but it can happen. The days of false positives from non related compounds are long gone. The most common false positive via EMIT II assay is from DXM which will sometimes show as a phencyclidine positive. EMIT II assay has a 3-6% chance of giving a false positive. Diluting a urine sample will usually not work in increasing ones chances of a false negative because of specific gravity tests and for the simple fact that EMIT and especially GC/MS are very sensitive.