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tlc tests for home made analisys

Fi_Di_Bot

Fi_Di_Bot

Son Of Botany - Green Block Original Shrdana
Veteran
anyone use tlc (thin layer chromatography) tests at home? they work? i see some give out thc, cbd & cbn, others different cannabinoids (thcv, cbdn, ect ect) and i was interested in it but often in the ganja world they sell lot of useless stuff and, like all, i don't like to waste my money. tnx
 
mack 10

mack 10

Well-known member
Veteran
I'm lurking, intereseted in this too. Havent used any yet though. Cannalytics seems quiet straight forward.
mack.
 
purple_man

purple_man

Well-known member
Veteran
if i remember right, tlc can only give you a qualititive assasement (either yes or no for the different cannabinoids), but you can't assess the amount of each compound -> it's pretty useless for breeding/growing...

blessss
 
O

olekingkole

Active member
TLC is a lot simpler than GLC but there is still a learning curve. It took me about 2 months to learn adequate lab technique before I could get consistent results. The size of the spot on the glass plate is proportional to the amount of cannabinoid in the sample. You
create your own standard and run it with the sample and then compare the size of the spots. Good luck!
 
Fi_Di_Bot

Fi_Di_Bot

Son Of Botany - Green Block Original Shrdana
Veteran
purple_man said:
it's pretty useless for breeding/growing...
blessss
Click to expand...

yeah purple_bro we can live surely without but for breeding ...
1) it can help when you got many strains that you'd like to bring to a competition. all tasty, yumm!... just do the test and choose the strongest two (in the italian cup you can have only 2 entries for category)

2) it can help to choose a true stallion! both in TY and in DolceVita magazines, there was an article from Shantibaba where he say that is possible to found males that put out resin (on the stem, leaves, etc), more thc produce a male and more % to get the same result on his progenie.
so i belive few test can help to choos ethe best male (maybe you got all or the best few male plants with the same, size, vigour, number of internodes, the aspect.. they could be different in % of resin and its cannabinoids).

olekingkole: tnx for the infos. the montanabiotech tests had an extra software that help you to read the spot's size.

let's see if i get more info :D
 
gurnt

gurnt

Member
Slow down I looked in to this a few years back . you can find the things you need on e bay for <$20 you need to buy some weed that been tested as your control( where you got it from had it tested for % of thc) to see what side spot you get
 
RulaTone

RulaTone

Well-known member
Veteran
I find it stupid to ask a 10x5cm plate how good a ganja is.
Smoke it and you will know.
Its like wines......
a good and trained mouth will be 10 times more useful in describing an effect.

I have a question Fi_Di:
you said you would find tlc useful to enstablish wich is the best weed to carry at a competition.
Would you carry the ganja with the highest value on the plate, or the one you and others find "better" smokin it?

In a competition judges smokes and tell which is the better...
they dont give a fudge on how much thc is there.
The one that makes you higher is the better in my opinion.
And not always is the one with more thc.

TLC would be useful to compare among different weeds, or as others said when if you have a secure standard to compare. But having such a standard is not an easy task, especially in our country. And even then comparation is still an "eye-thing" without any firm numbers, and it can lead to confusion.
Tlc can be useful if you are searchin CBD only genetics
 
Fi_Di_Bot

Fi_Di_Bot

Son Of Botany - Green Block Original Shrdana
Veteran
RulaTone said:
you said you would find tlc useful to enstablish wich is the best weed to carry at a competition.
Would you carry the ganja with the highest value on the plate, or the one you and others find "better" smokin it?
Click to expand...
Hi Rula! i will bring the best tasting and/or most powerfull.. but what is strong for me sometimes isn't so strong or so tasting for my homies and viceversa
In a competition judges smokes and tell which is the better...
they dont give a fudge on how much thc is there.
The one that makes you higher is the better in my opinion.
And not always is the one with more thc.

TLC would be useful to compare among different weeds, or as others said when if you have a secure standard to compare. But having such a standard is not an easy task, especially in our country.
Click to expand...
ok
And even then comparation is still an "eye-thing" without any firm numbers, and it can lead to confusion.
Click to expand...
few have developed a software that allow you to turn into numbers the eye reading, a bit too much expensive
Tlc can be useful if you are searchin CBD only genetics
Click to expand...

tnx all for your opinions! for the mo no intention to buy any tlc test.
have a nice time
 
RulaTone

RulaTone

Well-known member
Veteran
You're welcome Fi.Di! Just my two eurocents
I'm not an expert and never done any single test, so lets wait someone with a deeper insight.
Have a nice weekend man.
 
O

omera1

Member
gurnt said:
Slow down I looked in to this a few years back . you can find the things you need on e bay for <$20 you need to buy some weed that been tested as your control( where you got it from had it tested for % of thc) to see what side spot you get
Click to expand...

can you list the needed chemicals ?
 
N

NotaProfessor

Active member
olekingkole said:
TLC is a lot simpler than GLC but there is still a learning curve. It took me about 2 months to learn adequate lab technique before I could get consistent results. The size of the spot on the glass plate is proportional to the amount of cannabinoid in the sample. You create your own standard and run it with the sample and then compare the size of the spots. Good luck!
Click to expand...
[Emphasis mine -NAP]
This is a big assumption that depends upon a lot of other things being perfect for it to work out. In practice that perfection is usually out-of-reach.

One of the most important variables (and one of the hardest to control) is thickness of the silica layer on the plate. It has to be extremely consistent across the plate and that is not an easy task. Another variable is the amount of tested material deposited on the plate - a drop is not the same every time. Microliter pipets are expensive. Also, spot diameters are not linear with actual concentration (they vary with the square root of the diameter of the spot), so multiple standard concentrations would need to be spotted on each TLC plate to set up a calibration curve. Even then it's at best a guess.

My opinion as an analytical chemist is that you are restricted to getting order-of-magnitude values from TLC. You could get quantitative numbers from TLC if you went and extracted the actual substance from the silica gel and weighed it. However, the equipment and technique for microgram extraction and measurement is beyond the usual grower's expertise and pocketbook.
 
O

OG_TGR

Member
olekingkole said:
You create your own standard
Click to expand...
Wait....what!? That is awesome!! I assume you need a known THC content strain, though? I have hovered over GC units "Purchase" button so many times, only to be discouraged by the fact that I thought I could never get a standard where I live.
Can anyone possibly elaborate on this, creating a THC standard for GC?
 
N

NotaProfessor

Active member
OG_TGR said:
Wait....what!? That is awesome!! I assume you need a known THC content strain, though? I have hovered over GC units "Purchase" button so many times, only to be discouraged by the fact that I thought I could never get a standard where I live.
Can anyone possibly elaborate on this, creating a THC standard for GC?
Click to expand...
One way is to buy some weed that has been tested by a lab already and use that as a reference. Process the "standard" the same way you do your sample.

I have to digress to express some caution here wrt significant figures. Just because a lab reports, say, 25.43% THC, doesn't mean that the "standard" has that level of precision (i.e. 4 significant figures). Just because the instrument produces numbers with that many digits doesn't mean that each digit is significant. In any analysis the significance of the result is determined by the precision of each measurement leading up to that result. Weighing of the sample, amount of solvent added during extraction, sample size injected into the GC/MS, and finally the sensitivity of the detector all are measurements that have varying levels of precision.

To arrive at what the significant figures are for an assay you look at those measurements and find the one with the least number of significant figures and that is the limit of the significant figures in the result. For example, weighing a sample with a milligram scale results in 3 significant figures; measuring the amount of solvent is 2 or 3 figures (depending upon the device used to measure the solvent); the sample size injected into the GC is usually two to three sig figs; the sensitivity of the detector varies from 2 to 4 sig figs. What was the least number in that list? 2, so the final number is only good to 2 significant figures, or for the example, 25%. Anything after the 5 is useless.

Another issue that impinges upon the significance of the result is repeatability. If the lab ran multiple shots of the same sample, how would the result vary? Chances are that you will find the results vary enough that only 2 significant figures can be reported. Getting the sample analyzed at multiple labs (ideally, multiple times through blind submissions) would increase the reliability of the third significant figure through averaging.

Combine the difficulties of attaining highly significant measurements (even in a commercial lab) with the other issues I noted previously in this thread, you are likely to end up with only a single digit of precision (i.e 20% or 30%) in the results of TLC quantification.

So yeah, you can make your own standard but it will be limited by the precision of the analyses that determine the level of THC in your standard. And even if that was good, the variability in TLC analysis degrades your results to an almost illegible value.
 
O

OG_TGR

Member
NotaProfessor said:
One way is to buy some weed that has been tested by a lab already and use that as a reference. Process the "standard" the same way you do your sample.

I have to digress to express some caution here wrt significant figures. Just because a lab reports, say, 25.43% THC, doesn't mean that the "standard" has that level of precision (i.e. 4 significant figures). Just because the instrument produces numbers with that many digits doesn't mean that each digit is significant. In any analysis the significance of the result is determined by the precision of each measurement leading up to that result. Weighing of the sample, amount of solvent added during extraction, sample size injected into the GC/MS, and finally the sensitivity of the detector all are measurements that have varying levels of precision.

To arrive at what the significant figures are for an assay you look at those measurements and find the one with the least number of significant figures and that is the limit of the significant figures in the result. For example, weighing a sample with a milligram scale results in 3 significant figures; measuring the amount of solvent is 2 or 3 figures (depending upon the device used to measure the solvent); the sample size injected into the GC is usually two to three sig figs; the sensitivity of the detector varies from 2 to 4 sig figs. What was the least number in that list? 2, so the final number is only good to 2 significant figures, or for the example, 25%. Anything after the 5 is useless.

Another issue that impinges upon the significance of the result is repeatability. If the lab ran multiple shots of the same sample, how would the result vary? Chances are that you will find the results vary enough that only 2 significant figures can be reported. Getting the sample analyzed at multiple labs (ideally, multiple times through blind submissions) would increase the reliability of the third significant figure through averaging.

Combine the difficulties of attaining highly significant measurements (even in a commercial lab) with the other issues I noted previously in this thread, you are likely to end up with only a single digit of precision (i.e 20% or 30%) in the results of TLC quantification.

So yeah, you can make your own standard but it will be limited by the precision of the analyses that determine the level of THC in your standard. And even if that was good, the variability in TLC analysis degrades your results to an almost illegible value.
Click to expand...

Very informative, gives me a lot to think about. Thank you very much for taking the time to pen a thorough reply!
 
purple_man

purple_man

Well-known member
Veteran
exactly what notaprof wrote, even if you base your sample on sampled buds, who know how accurate their standards have been, which part of the plant been sampled, how was the sample stored and handled before preparation, etc... and every successive measurement will be scewed by the predecessing one, hence rather utopical, unless meant for marketing purposes (as in: i got that 50% thc, tlc tested kush cookies or such) :/

blessss
 
O

OG_TGR

Member
So, I believe someone commented earlier on this thread or one similar to the extent of, how do the testing labs acquire standards in the US if they are all Federally controlled? Is there any way of creating a standard, within "controlled territory", that could produce a reliable baseline? I suppose you could run several tests from the same sample and then average? Still, you are only able to be as accurate as your own inconsistencies, then the margin of error grows exponentially.... :/
 
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