GC-MS vs. standard testing

[sacchrone]

I have the chain of custody form for my drug test this Friday. Is there a way to tell what my prospective employer is paying for? The only things on the container seal sticker which I don't understand are "OTS-RTP 3000". This is a big bucks firm so my fears are GC-MS...

Thanks for any info.

[sacchrone]

and...is there any creedence to the idea that Ibuprofen in high doses (how high I wonder) can interfere with GC/MS results.

I can't help but think I am going to be tested GC/MS out of the gate...It's a contract gig at a major pharmaceutical company.

Thanks for any info or thoughts!

[sacchrone]

OTS = Occupational Testing Services
RTP - Research Triangle Park

[Burnt Toast]

and...is there any creedence to the idea that Ibuprofen in high doses (how high I wonder) can interfere with GC/MS results.
The GC/MS can distinguish between scripted/OTC meds and illicit substances.


I can't help but think I am going to be tested GC/MS out of the gate The GC/MS is only used to confirm any positives that occur on the initial assay screen. Any drug panels that tested negative on the initial assay screen will not undergo the confirmation GC/MS. It would be too costly to run the GC/MS on all of the drugs of a given panel.

This is a big bucks firm so my fears are GC-MS...If youre fearing the GC/MS because of its numerically lower cutoff threshold, then dont be. Read post #18 in this thread as to why: http://boards.cannabis.com/drug-testing/171645-have-you-failed-after-30-days-weed-free.html

[sacchrone]

Thanks so much for the info. Basically, what you are saying is, it's not worth the money for a company (even a fortune 500 pharmaceutical company like the one I am applying to) doing a pre-employment screening to spend the money out of the gate on a GC/MS, and if it is a positive result, then the GC/MS is a failsafe with an exact number associated with it to confirm, correct?

I have read the thread you referred to before (and many times since). I don't completely understand the science of what you are saying (and thus the subsequent logic behind it). If the two tests are somewhat "functionally equivalent" what is the use of GC/MS?
Sorry, I don't mean to be thick or waste your time, just don't understand completely.

I have been testing negative on the first void of the day for about a week now (while still strenuously exercising the night before with a no fat diet). Yes, I am being very neurotic/paranoid and trying to have all bases covered for my test on Friday. I plan on drinking a couple g*t*rades a few hours before the test with a couple cups of water, a few glasses of water an hour before, and moderate versions of the rest of the dilution sticky. Reasonable plan? I don't want to go overboard and get a dilution, but I don't trust the results I have been getting in the eleventh hour. Again, sorry, just a newbie with all this.... Will stop bothering you after this.

Thanks so much for your attention to this. You've been very patient.

[sacchrone]

Did I just answer the question in my second paragraph in my first? And this is why they are functionally equivalent? please confirm.

The other friendly advice requested in my last post would be greatly appreciated. Thanks!

[Burnt Toast]

Before you can understand how drug testing devices work, you have to understand how the human body processes THC.

In summary, THC enters the body in its ingested form, metabolized, and exits the body as 31 different metabolite concentrations. The most prevalent form of these metabolite concentrations is the 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (aka THC-COOH) metabolite concentration.

Immunoassays, being non-selective testing devices that they are, recognize all 31 metabolite concentrations combined, instead of the metabolite concentration that matters the most (being the THC-COOH metabolite concentration). Because of this, assays are calibrated at a fixed cutoff threshold of 50 ng/ml. They are a "go/no-go" endeavor and have no ability to yield a quantitative value.

On the other hand, the GC/MS, being selective and more accurate, only recognize the metabolite concentration that matters the most (the THC-COOH metabolite concentration). In order to test negative on the GC/MS, only the THC-COOH metabolite concentration must register below 15 ng. Because the GC/MS only recognizes the metabolite concentration that matters the most (THC-COOH), the cutoff threshold has to be set numerically lower in order to make the two types of tests functionally equivalent.


Basically, what you are saying is, it's not worth the money for a company (even a fortune 500 pharmaceutical company like the one I am applying to) doing a pre-employment screening to spend the money out of the gate on a GC/MSEven "Fortune 500" companies are bottom-line conscious (as with any line of business). To the corporate bean counters, the expense of using the GC/MS as the primary analysis on every Tom, Dick, & Harry on the company payroll is not justified. On a test involving multiple panels (drugs), it would run into the hundreds, if not thousands of dollars to run the GC/MS on all of the drugs on a given panel. The company, particularly one with a large payroll, would go belly-up and in short order.
The use of the Immunoassay as the primary analysis is much more pleasing to the bean counters because of its lower cost.


If the two tests are somewhat "functionally equivalent" what is the use of GC/MS?
The GC/MS is used as the confirmatory analysis because of its accuracy, and most importantly, its ability to provide quantitative values. A positive result should never be substantiated nor accepted devoid of a quantitative value.