Potency or strength of THC - exactly how is it measured?

Basic Growing Info
#1

Ive been Googling this and the answers Im finding seem somewhat contradictory and mostly vague or not defined precisely.

Potency seems to be based on “dry” weight, but does anyone know how “dry” that is when it comes to official potency measurements, and how its measured, or determined?

Do they base it on some ratio of fresh wet weight to some specific % of dryness, or is there some absolute measurement of moisture left in the sample?

In other words, do they take a 100gm wet sample and dry it until it only has 15% (or what ever) of the original moisture content and then do the analysis?

Or do they take that same sample and dry it out until it has zero moisture and use that weight?

Or do they use some specific amount of moisture left in the dry sample as a goal for measuring the THC/CBD etc?

Or is this like almost everything else in this hobby, and there are 37 “right answers” depending on who you ask? :slight_smile:

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#2

Something like that… Now that being said THC percentage is percent of the bud itself that is covered in trichomes and I don’t put alot of stock into thinking that because something has a high THC percentage that it will be super potent, I feel that comes more from the terpenes and how they react with each other

Didn’t really answer your questions and I’ll probs get corrected shortly lol but damn fine subject for a thread

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#3

Larry, typically they desicate the flower sample and then extract the THC from the flower with ethanol. That sample is then ran through a gas chromatography or mass spectrometer to determine the %of the solution is THC.

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#4

Ah thank you, but that still leaves me with a few questions.

The main one is do they use the desiccated weight of the sample to calculate the ratio or the weight of the oil they extract or the weight of the “green dragon” alcohol mixture?

Im trying to get at least a vague idea of how to estimate THC/CBD yields on my own, but I have no idea which numbers to use or which one the labs use.

Individual growers numbers are going to be all over the place depending on how “dry” they make their bud and how closely they trim, etc.

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#5

Good point. The word potent can be misleading here. Its the % of THC or CBD I was interested in - those numbers you see when you order seeds and read about the plants and al these new “high potency” plants having up to 30%.

My question is 30% of what exactly? :slight_smile:

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#6

I dont know the specifics, just the basics. I do know it is a specific weight of flower to a given volume of ethanol, but I dont know the details.

If you are wanting to do some at home testing of THC, look into TLC, Thin Layer Chromography. Something like this…

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#7

Darn. Im trying to figure out what the relationship is between those advertised “laboratory” THC/CBD % numbers and our home growing numbers.

When a lab says “desiccated” Im pretty sure that means zero moisture - which is a LOT dryer than we would normally do - especially smokers.

I know when I “dry” my bud prior to processing, the final dry weight has been anywhere from 24% to 28% of the original wet weight.

But those numbers dont tell you anything about the actual water content or how much the weight would go down if ALL the water was removed.

This isnt really that important a question I guess. Even if we knew exactly how a lab does it, I dont see any easy way to accurately translate that into how we do it at home.

Id love to play around with some of that stuff, but its outside my budget.

Im mainly just curious about how the labs get their numbers compared to how we do it at home :slight_smile:

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#8

not that i know how labs test, but unless a bud is fully dried out its water weight would contribute to the overall weight and would skew results unless it was taken into consideration.

… and maybe when in doubt smoke more?

and i used 22-24% from wet to my prefered dry, but buds donet even hit that now, just straight to resin…

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#9

Thats exactly my point in asking these questions - how dry is dry? :slight_smile:

You have been going a little drier than I ever did - except by accident when drying in the oven!

I dont smoke, so all I do is Green Dragon to RSO to capsules, but I like to dry my bud first. Its less water to drive out after removing the alcohol. For some reason I dont mind letting the bud dry for a week or two, but I hate spending an extra 1/2 hour at the stove driving off the water! :smiley:

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#10

well as of late ive been only drying 2-3days max then solvent extracting and the amount of water that gets pulled over seems very nil even though you wouldn’t think so with still spongy buds, but my guess is it relates to cells being decently deflated to a sense water wise vs say frozen buds, where that cell walls may of been burst from ice formation, and or say dry bud where your solvent can permeate or extract more from the cells due to its slightly to dedicated nature…

Just something ive been playing with.

But yeah dont know on what they determine as the weight, but id happen to guess all water removed and or accounted for and minused out of the total weight would be the most logical answer

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#11

Thats my thought as well.

#12

I’ve wondered the same thing - sort of. I knew a closet grower from about 15 years ago who had some dried bud that was in baggie. She said she grew it herself, but it looked quite a bit better than the plants she had in her little ebb and flow system. Anyways, the trichomes were massive and seemed to cover the entire buds in the baggie. There was a layer of trichomes in the bottom of the bag that looked like sugar. So we scooped up some of the triches and a little bud and ripped a big bowl before heading out to brunch. However - the smoke was only OK. I expected to be blown away, but was far from it. I had to break out my own bud to ensure we had a good buzz before sitting down to eat and drink for the next few hours.

Around that same time, I was growing Neville’s Haze, Serious AK-47 and White Widow. The AK and WW had some impressive trichomes, but the Neville’s Haze wasn’t nearly as impressive. But the Neville’s Haze would take less to get you completely stoned, and the effects would last much longer.

So my question would be: exactly how is the true potency of marijuana measured? It can’t be a simple THC ratio.

As for how marijuana is tested, here are a few techniques that I’m adjacently aware of:

Cannabinoid analysis / potency profiling: UPC2 (Ultra-Performance Convergence Chromatography)
Terpenes: GC-FID/MS (Gas Chromatography Flame-Ionization Detector Mass Spec)
Heavy Metal / Elemental Analysis: ICP-MS (Inductively-Coupled Plasma Mass Spec)
Pesticide Discovery / Analysis: UPLC/MS/MS (Ultra-Performance Liquid Chromatography Tandem Mass Spec)

Personally, I’m thinking the true potency is in the magic that happens within the convergence of the THC and terpenes. They are both measurable, but I believe it’s the combination that makes one strain “stronger” than another.

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#13

Not only the terpenes, but the other minor cannabinoids, there are hundreds of them. They make each high slightly different. :+1::seedling: pure THC (distillate) is actually quite boring.

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#14

it’s generally measured by THC + (THCa * 0.877) = total THC

this is because THCa is only 87.72% THC with the other 12.28% being CO2, which is lost during decarboxylation. THCa has 1 carbon and 2 oxygen atoms extra compared to THC. The same is true for CBD/CBDa, an extra CO2 molecule.

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#15

going to fully agree with @ ReikoX on this. pure thc at 84 % does not even buzz me, its a vape where thye removed everything except thc supposedly

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