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chromatographI was driving with the car and was involved in a minor traffic violation and I was submitted to a drug saliva test. The sample was analysed in the laboratory using liquid chromatography with tandem mass spectrometry (LC–MS/MS) and found to be positive for Δ9-THC at the rate of 12.5 ng/ml.

The only problem is I do not smoke or eat cannabis, at least not in the last 20 years. Somewhere something in the analysis went wrong. I have much more documentation to share regarding this case.

I will have to defend my case in court. At this moment I have already made two appearances in court and every time managed to convince the judge that something is not right and I was allowed more time to prepare my case. I am convinced that with the right knowledge I can defeat this claim against me (and at least as important to me possibly many other people that before me suffered this same fate).


I was exposed to a cannabis product via a neighbour of mine prior to the test. He is a stoner, which means that his life revolves around the cannabis culture. Before I got tested I talked to him for maybe 10 minutes. He was not smoking cannabis at that moment, but he told me about his shopping trip he had to Amsterdam the day before and where he bought fresh flowers of the cannabis plant. It is the green dried flowers of the cannabis plant that have a very specific smell to it. He bought I think 3 or 4 different varieties of this.

So what I did is out of curiosity and interest I smelled to each bag. So that is the source of the contamination I had. The only problem is that in reality this could not have led to a positive THC test to the amount of 12.5 ng/ml (this is actually even the corrected value, because the detected value was 17.9 ng/ml).

The standards that the forensic lab commits to are very robust and are international standards. From what I understand is that these standards account for passive smoking which should not lead to a positive test. So my judgement is that somewhere in the analytical process the values got to be exaggerated, but I do not know in which direction my focus should be. I have gathered quite a bit information regarding liquid chromatography and am hoping to have an answer to this question with the right help.


In the coming few days i am hoping to receive more analytical data from the lab that did the analysis and i will share it here on there forum if that is ok.


Does anyone knows the relevance of sample volume on the final detected values? I am thinking in this direction because I gave a really large volume of saliva to be tested.

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    $\begingroup$ Could you be exposed to the smoke as a passive smoker? Or using any cannabis related product? The analysis might not be off, just pointing to wrong conclusion. $\endgroup$
    – Poutnik
    Commented Apr 19 at 4:56
  • $\begingroup$ I'd try to obtain the analytical report and check how the lab validated the method and especially how they run quality control samples (QCs) and how they account for carryover. Possibly your sample has been injected after either a high-level calibrant or after some junkie's saliva, and the remaining THC has been carried over to the analytical run for yours. And find the layer who is familiar with regulatory documents for DOA tests in your country. $\endgroup$
    – andselisk
    Commented Apr 19 at 5:32
  • $\begingroup$ Thanks for the reply andselisk, i am trying to get all the documentation from the lab concerning my case. They really are not willing to openly share the information with me which i find very frustrating. I have used this argument successfully in court 2 time saying that without it i cannot properly defend my case. The judge ordered the lab 2 time to share the requested information. So the info is coming to me bit by bit and on my specific request and judges orders. Which means i need to know what to ask for and where to look out for possible mistakes. Kind regards. $\endgroup$
    – centrino
    Commented Apr 19 at 5:46
  • $\begingroup$ I'm afraid your reply to Poutnik kind of leads you away from the plane of analytical chemistry into the field of jurisprudence. I would assume the analytical results are likely accurate, and now the question is how the court will react to your wish to smell cannabis and having a stoner as a friend. Shall you have new details, please feel free to edit your question, just in case the analysis came out to be biased. I would also advise not to ignore the rules of the English language (I is the only pronoun form that is always capitalized in English), especially if you submit docs for the judge. $\endgroup$
    – andselisk
    Commented Apr 19 at 5:57
  • $\begingroup$ No Andelisk it is not true, i have reviewed many studies regarding this issue and all agree that the standards set forth agree that even secondary cannabis smoke is accounted for in the tolerance level which is 10.0 ng/ml Seeing that i did not even had a contamination with secondary smoke but only the "air" of fresh cannabis this could realistically never lead to a positive outcome. I am sure that somehow the measurements were exaggerated which led to this level of detection, i need to find out where and how. Thanks. $\endgroup$
    – centrino
    Commented Apr 19 at 6:03

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