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Purity Testing GCMS HPLC etc Question

- Tue, 28 Feb 2017 08:07:46 EST LObRvGV/ No.78584
File: 1488287266677.jpg -(11486B / 11.22KB, 439x373) Thumbnail displayed, click image for full size. Purity Testing GCMS HPLC etc Question
This is an email I sent out, but feel free to take a whack at it.

From the given information on the FAQ:
>Then we perform a qualitative analysis on each component identified where possible,
>comparing each substance with a pure reference standard.
>Our results directly provide the result of the salt of the substance, as we’re
>using a salt as a reference standard. The quantitative results are provided using
>a calibration curve from a reference standard.

as well as the techniques listed here https://energycontrol-international.org/drug-testing-service
It seems that almost all of those techniques can be used to generate a quantitative purity result, e.g. GCMS, LCMS, HPLC, UV/Vis.

So can you try to fill in the blanks here for me?

Generate pure quantitative result based on reference standard.
Calibration curves
Obtain substance % percentage.

How are these calibration curves created and how exactly are the curves used to determine the % percentage? Is it done by hand? Done via software?

The reason I ask is so I can understand and explain how people have reported widely varying purity results returned from the EC lab. In one case, someone sent to EC two samples of 4-MMC from the same batch with no obvious signs of cut, yet "the same shards came back with one 85% result and one 45% result." Why is this?

It is not the first error I've heard of, and I'd like to know, please ask your lab techs how perfect your quantitative test method is, and how much error tolerance is acceptable? Do you ever test twice to verify? For instance, testing heroin with HPLC and LCMS to compare both machine's quantitative data?
Lydia Craffingsune - Sat, 04 Mar 2017 20:09:43 EST WRu+rVKy No.78586 Reply
>"the same shards came back with one 85% result and one 45% result."
Sounds like they might have not been mixed all the way. The pure 4-MMC powder must have been cut with a filler or a stabilizer or something, and when you got the mixture it wasn't homogeneous. Improper mixing can result in 'hot' and 'cold' spots where there might be a lot of a little of the active ingredient compared to the average. That, or the business could just suck. I suppose that's also an option.
breakabond - Sun, 05 Mar 2017 01:52:45 EST LObRvGV/ No.78587 Reply
So you think it's unlikely for human error (from the lab techs) to be the cause of the imprecision?
William Cundershaw - Sun, 05 Mar 2017 11:17:59 EST ltcKYWSL No.78590 Reply
> The pure 4-MMC powder must have been cut with a filler or a stabilizer or something
OP said crystals, though.

I think it's possible. Then again, it's also possible that the crystals have varying purity, because who knows what procedures are followed in the labs making it (maybe they mix the good and bad batches together).

Do they give a report, or just a single number?
breakabond - Sun, 05 Mar 2017 13:10:32 EST LObRvGV/ No.78591 Reply
1488737432787.jpg -(135970B / 132.78KB, 1164x657) Thumbnail displayed, click image for full size.
Its energycontrol, they charge 60 for % then $80 for pdf report (like wtf man9
trypto - Mon, 06 Mar 2017 00:52:16 EST ltcKYWSL No.78592 Reply
That sucks. So it's drugs made from a lab that's not trustworthy, and totally opaque... tested by a lab that a bit trustworthy and a bit translucent... Inconsistency is inevitable.

Vehk !7HYGxe5v5c - Wed, 15 Mar 2017 22:49:59 EST l5Akm3J6 No.78601 Reply

The compound in the bottom right is incorrectly labelled. The compound pictured is methadone, while it is labelled as methedrone, which is a methcathinone and related to mephedrone.

Step up, fam.
Walter Goodwater - Thu, 16 Mar 2017 21:31:37 EST ZUVcy1Vx No.78607 Reply
1489714297151.jpg -(4617B / 4.51KB, 259x194) Thumbnail displayed, click image for full size.

A reference standard is a documented, authentic sample of the chemical you are looking to analyse for.

You dilute the reference standard in solvent at a range of concentrations, generally 5 different conc. are used for a good calibration curve.

You set up the instrument (GC/MS/HPLC/UV ect.) and inject each of those 5 standards you prepared.

The plot of detector response (peak area) as a function of each standard concentration should be roughly linear, fit a least squares line and use the equation of that line to calculate the amount of analyte in your test sample based on the peak area it gives.
Walter Goodwater - Thu, 16 Mar 2017 21:34:39 EST ZUVcy1Vx No.78608 Reply

this process is not nearly as simple as it sounds.

if you really want to test the lab's accuracy weight out a decent sized sample of a compound (~500 mg) and grind it well, then submit two samples of the same grind. They should be within 10% or so of each other

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Please be descriptive with report notes,
this helps staff resolve issues quicker.