Chromatography Forum

I'm a defense attorney and need to know more about GC/MS and meth. I'm getting the McMaster's book (I think) from the local college but don't have it yet.

I believe I understand the chromatograph and mass spectrum graphs, but still have a couple questions/issues...

1. I have two chromos, one for a client substance and another for what I believe was government meth. Both have a peak at about 5.36 minutes and the spectrum on each indicates meth. Is meth always going to peak at 5.36 or so, or is that going to depend on the specific attributes of the GC that is used? Like the carrier gas and all that other stuff that I don't quite understand yet.

2. Anyone volunteer to look at a chromo for me through e-mail? It's from several years back and the case is closed. There's an early peak that is DSM3 or something, then a meth peak, then a crazy goofy mountain peak - not a spike - around 9 to 10 minutes. I don't have a spectrum for that but I need to know why the peak showed up like that.

3. From what I understand, meth's spectrum is focused on masses 58 and 91. Is that dependent upon the machinery used? If it is not, what are the main masses for ephedrine and pseudoephedrine? I'm under the impression they are similar and an expert can explain how they are different. However, I can't find a sample spectrum for either substance.

4. How much of a substance is actually needed for testing? Clients seem to think that the state needs two tests to get into evidence and if they get popped with a small amount they think the state can't test it twice. First, the state doesn't need two tests. Second, I'm under the impression only a very, very small amount is needed to test with GC/MS. However, the preliminary tests may consume more of the substance.

Thank you for any responses.

Erik O'Daniel

I am not really an expert on illegal drug analysis but I can reply some of your questions:

1) Meth is not always going to peak at 5.36 min, it will depend on the chromatographic conditions (column, carrier gas, temperature gradient) and if meth has been previously being derivatized (chemically modified) or not. But normally analytical chemists inject the pure compound first to make sure that the retention time and mass spectrum are eluting where they should, followed by a blank followed by your sample. If a lab has come back telling you that your client substance was meth, probably he can proove it.

2) The "crazy goofy mountain peak" may not mean anything. This might also depend on the chromatographic conditions used, once the compound of interest is eluted from the column, the analytical chemist might ramp up the temperature of the column in order to elute all other compounds out of the column that are not meth (i.e. impurities etc), re-equilibrate and proceed to the next analysis. This can lead to a co-elution of several compounds and give you that potato peak. What is important is that these compounds do not co-elute with your compound and a clean mass spectra along with the retention time might be able to proove so.

3) This will depend on whether meth was derivatized or not before the analysis (I would just guess that in this case it is not) and the operational conditions (i.e. you can brake the molecule more or less depending on the energy you provide to the molecule). But again the analytical chemist should have used before pure meth to demonstrate that these are the masses obtained at the operating conditions. Ephedrine and pseudoephedrine are optical isomers (R, S) so they have exactly the same mass and most likely they will give exactly the same fragmentation pattern (i.e. same mass spectrum). They can be resolved only through chiral analysis (you need either a chiral column -cyclodextrin type- or special type of derivatization)...

4) Are you talking about blood test or powder testing? In terms of powder I am sure they do not need much, in terms of blood it will depend. Probably the law defines what concentrations of meth or it's metabolites are considered unlawful if detected in your blood (i.e. they are not going to sample two liters of your blood, concentrate and analyze it in order to get the meth peak).

I do no know what you are trying to prove in this case, but if ever you are trying to invalidate certified lab results, that would be very difficult. You will probably need an expert opinion who will go through the fine details (i.e. was a blank was run before the analysis of the sample etc...). And if they have more sample left they can always go back and redo the analysis... But who knows, maybe you will have an Anne Marie Gordon case luck (I think that was the name)

That was VERY helpful. One problem we have is that we don't know the state lab's protocols and the prosecutors aren't very helpful in assisting us. I've heard about running blanks and such and the comparison run. The background info helps a bunch.

1. Heard about derivitizing or whatever, but haven't learned much on that.

2. Makes sense. The private lab test also had a slow peak at the end, but it wasn't as high.

3. This info is beyond my knowledge, but I printed it and it's going in the file.

4. Not blood.

The case involved a defendant who possessed Vita-Blend, a niacin powder used as a diet supplement. Also used to cut meth so people weren't using straight meth. It was in a baggie that had previously been used to hold meth, so the state lab test came back positive. Private testing showed that the substance in the bag wasn't a controlled substance.

Basically, state lab stops their action when they get a positive for meth, even if there is 100 grams of other substance there and the defendant is claiming no knowledge of the meth.

Again, thank you very much for the reply.

Erik

Most analytical chemists with some reading will be able to tell you exactly what method was used from the state lab. Most likely they used published methods or recommended protocols like the ones found in the link below:

http://www.unodc.org/pdf/scientific/stnar34.pdf

The method of the state lab is probably quantitative and not only qualitative so there should be able to tell exactly how much meth was contained in the bag. Maybe you should do the same. If the amount is really as small as you claim, it will be close to traces and you might be able to support your statement... Traces might mean 1/100 of a normal dose.

In this case it would be useful information to know the exact amount that the state lab started, if they used any preconcentration methods etc...

Good luck...

For a suspected drug substance most drug labs do what is called a dilute and shoot, dissolve some of the substance in an organic solvent and shoot it onto a GC, GCMS, or other instrument to see if it matches up with a controlled substance that they are looking for. In terms of amount required to test, a few milligrams is a lot for this type of testing.

Kostas gave very good answers, especially to how to invalidate results. You need an expert in the technique if you are trying to invalidate the results of a drug laboratory, they have very well validated and established protocols, and they spend a lot of time and effort to make sure the results will hold up in court.

If you want to cast doubt on the results find a good testing lab, which may not be easy, test the powder, then test the baggie separately. Just as a side note, if the defendent knew the bag had been used for meth and put in a substance used to cut meth, he has a definite perception problem going to court.

The state lab was going to stop as soon as they found meth, they were looking for controlled substances, they found evidence of a controlled substance, and to them it doesn't matter what the balance of the substance was.