How do I make sure the sample I submit for testing is truly representative of the batch?

A) Plant Material for Testing

There can be quite a bit of variability in plant samples, even from the same plant. Buds near the top can be different from those near the bottom, etc. To properly collect plant samples for testing, please follow these guidelines:

Always try to collect many small samples from different areas of the batch unit to be tested (bag, plant, strain, grow, etc.).  Just grabbing one big bud might result in getting results that are not representative of the whole sample. Make sure the sample submitted has all of the same qualities as the batch as a whole. For example, if the batch is two thirds big buds and one third smaller buds, then make sure the sample submitted has about two thirds samplings from big buds and one third samplings from small buds. If the buds are so large that even just one bud is larger than the required submission size, it is better to cut small pieces off of many buds than just submit one big bud. Take pieces from many buds, some from bud tops, some from bud bottoms, some from interior, some from exterior. Try to take a "representative sample," which means the totality of what is submitted for testing should have about the same overall composition as the entire batch.

When collecting the sample, try not to crush or otherwise disturb the bud or part of a bud during the process.  A small scissors often works better than trying to tear off little pieces. Clean the scissors frequently with ethanol (>75%, 150 Proof) or isopropanol to remove any resin buildup and clean all tools particularly well between batches to avoid cross contamination by microbes or toxins that may be present in one batch but not another. Make sure the tool is clean and that all solvent is evaporated before using the tool, especially if residual solvent testing will be performed. Also, make sure to wear gloves and safety glasses and work in a well ventilated space away from open flame or spark source when using flammable solvents.

Don’t handle the bud too much and don’t put it in a shirt pocket.  Dirt, oils and bacteria from your hands can contaminate the sample. Small fibers from your shirt will stick to the plant.  Best to use a tweezers or clean gloves, if possible, and put it directly into a bag or other clean container.  Transport the sample in such a way that it doesn’t get crushed.

B) Concentrates

Concentrates (extract, essential oil, resin, BHO, CO2, waxes, shatters, budders, etc.) are almost always viscous liquids or even solids. Residual solvents get trapped or dissolved in the concentrate during the manufacturing process when the solvent is present in large amounts. Different cannabinoids and terpenes are present at high concentrations. Solids and viscous liquids with many components, such as cannabis extracts, are inherently heterogeneous because the different components can segregate differently at different temperatures and pressures and the rate of diffusion or mixing is very low. Even a process whereby the extract is heated to make it less viscous (flows faster) and stirring vigorously does not guarantee homogeneity. Among other reasons, when the extract is cooled back down, things may separate differently in different parts of the sample. That means sampling from different parts of the batch can give different results. To ensure that the test results are representative of a batch, it is important to submit samplings from many different regions of the batch - top, bottom, left, right, middle, etc. If only one test is desired, the client should mix those different samplings well in the container to be submitted and our techs will do their best to make sure the material submitted is stirred and sampled appropriately in the lab. Ideally, heterogeneous samples such as these should undergo multiple tests (client submits at least three different samplings of the same batch) to allow estimation of the variability within the batch.

C) Edibles

In order to check for consistency of results, multiple tests using different exemplars from the same batch to check for intra-batch consistency. Also, we advise that you conduct multiple tests using different exemplars from different batches to check for inter-batch consistency. 

Performing shelf life tests which involves multiple testing of your end-product over time to see how the results may change.


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    Jon Degallier

    How much edible sample is adequate? The brownie dosages (called hash bites) fluctuate from 30 to 40 grams each.
    Would 4 dosages be enough?

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