How to Prepare Flower and Oil Samples for HPLC Analysis

How to Prepare Flower and Oil Samples for HPLC Analysis

Ionization Labs - Flower & Oil Sample Preparation 

Purpose

This procedure details how to properly prepare HPLC samples from cannabis flower material and oil material.

Scope

This applies to all flower and oil samples prepared at the Ionization Labs Austin laboratory and any customer sites performing HPLC analysis of cannabis extracts or flowers.

Responsibility

It is the responsibility of the user to ensure that a calibrated pipette and balance are available, as well as a functioning sonicator and -20 °C freezer when preparing flower samples.

Materials and Equipment 

Materials:
  1. Flower/Bud
  2. Light Oil (~40%) Concentrate/Winterized Oil (~60%) Distillate/Isolate (+ 80%)
  3. Sample preparation kit

Equipment:

  1. 10-100 uL pipette
  2. Pipette tip tray with tips
  3. Electronic balance
  4. Mortar and pestle or coffee grinder Sonicator
  5. Vortexer
  6. Small spoon
  7. Large spoon
  8. 50 uL syringe
  9. 1 mL disposable syringe
  10. 0.25 um syringe tip filter

Safety Issues

Disposable gloves and safety glasses should be worn at all times when handling chemicals. Refer to Methanol MSDS in the event of skin or eye contact or inhalation.

Procedure

In this procedure, the operator will become familiar with two processes in sample preparation: 
Here is the suggested weight range according to the sample matrix:
  1. Flower/Bud: 250-450 mg
  2. Light Oil (~40%): 130-180 mg
  3. Concentrate/Winterized Oil (~60%): 100-150 mg
  4. Distillate/Isolate (+ 80%): 80-120 mg
Cannabinoid Sample Extraction - In this process, we are using methanol to extract the cannabinoids from the other organic parts of the sample. Methanol has the power to dissociate cannabinoids from the non-cannabinoid, organic sample they are bound to. Wether it's flower, crude oil, wax, isolate, or even most food-based cannabis products (except for gummies, that prep process can be found in the Knowledge base), the goal is to strip the oily, waxy, cannabinoids from whatever non-cannabinoid material they are attached to. This will be done by adding sample into an empty vial and then adding methanol to that vial to start the extraction. Vortexing the filled vial helps ensure the methanol is well mixed into the vial. Sonicating the vial after vortex helps bring out any last cannabinoids that may be hiding. Once sonication is complete, the 20mL extract vial is ready to be filtered through the 1mL syringe and micron filter.

Extraction Process

Flower Samples

  1. Grind the dry flower material with a coffee grinder until the particles are small and homogeneous. Pulse the material in 1 second intervals for 10 seconds.
    1. Optional: If the material is wet or sticky, freeze ~500 mg of flower material in the -20 °C freezer, for approximately 5 minutes, before grinding
    2. Remove the vial lid and place the empty 20 mL sample prep vial on the balance and tare the balance without the cap.
  2. Using the small spoon, add the suggested weight of ground flower material into the tared vial. After the addition is finished, promptly screw back on the cap to reduce solvent evaporation.
  3. If using an empty 20 mL sample prep vial and bottle top dispenser, add 4 mL of methanol to the vial and product.
  4. Record the strain, date of preparation, and exact mass in mg on the sample vial and in your notebook.
  5. Cap the 20 mL vial tightly, shake well or vortex, and then sonicate for 10 minutes at room temperature, ensuring that the water level in the sonicator reaches to at least half of the solvent height to dissolve the sample.
    1. Multiple sample vials of the same sample type can be sonicated at once.
    2. Be sure not to add too much water or the vial(s) will begin to float and fall over.
  6. After removing the sample from the sonicator, vortex the extract vial for 10 seconds.

Oil Samples

  1. Remove the lid of the 20 mL sample prep vial and tare the vial on the balance without the cap.
 
  1. Add the suggested weight of oil material to the tared 20 mL sample prep vial.
  2. After the addition is finished, promptly screw back on the cap to reduce solvent evaporation.
  3. Record the exact mass in mg on the sample vial.

  1. Using the 20 mL sample prep vial and bottle top dispenser, pump 4 mL of methanol to the vial and product.
 

  1. Vortex the vial for 5 seconds or until oil residue is no longer visible and no longer lodged on the vial walls.
  2. Place the 20 mL vial in the sonicator for 15 minutes at room temperature, ensuring that the water level in the sonicator reaches to at least half of the solvent height to dissolve the sample.
  3. After removing the sample from the sonicator, vortex and/or shake the extract vial.

Isolate Samples

  1. Remove the lid of the 20 mL sample prep vial and tare the solvent filled vial on the balance without the cap.

  2. If using an empty 20 mL sample prep vial and the bottle top dispenser: Remove the vial lid and place the empty 20 mL sample prep vial on the balance and tare the balance.

  3. Add the suggested weight of isolate material to the tared 20 mL sample prep vial. After the addition is finished, promptly screw back on the cap to reduce solvent evaporation. Record the strain, date of preparation and exact mass in mg on the sample vial and in your notebook.

  4. If using an empty 20 mL sample prep vial and bottle top dispenser, add 4 mL of methanol to the vial and product.

  5. Vortex the vial for 15 seconds or until there is the complete dissolution of the isolate into the MeOH solvent.

  6. Place the 20 mL vial in the sonicator for 10 minutes at ambient temperature, ensuring that the water level in the sonicator reaches to at least half of the solvent height to dissolve the sample.

  7. After removing the sample from the sonicator, vortex and/or shake the extract vial.


Serial Dilution Process - Applies to All Samples

  1. Place the small vials in the sample prep holding tray, from left to right starting with the green vial, followed by the yellow, and then blue. Label the vials with the strain, weight, and date they were prepared.

  2. Once sonication is complete, remove the sample prep vial from the sonicator and use the 1 mL syringe to draw up 1 mL of solution. Next, place a syringe filter on the syringe tip and dispense into the green cap vial.

  1. Dispense liquid in the syringe into the open green cap vial, discard the syringe and syringe filter, and put the green cap back on. Vortex the vial briefly.

  2. Discard the syringe and filter.

    IMPORTANT: DO NOT reuse the syringe and filter as this will contaminate your samples

  3. Set the micropipette to 40 uL and attach a clean tip.

  4. Unscrew the green cap and prepare the pipette tip for transfer.

    1.  Draw up 40 uL and dispense the green cap solution three times into the green cap vial.

      IMPORTANT: This is crucial for accuracy as methanol is not stable in a dry tip. 6.2. The pipette has two positions when moving the thumb downward.

    2. The first position is for drawing up liquid.

    3. The second, being all the way down, is for dispensing.

    4. IMPORTANT: If the sample is drawn to the 2nd position, the pipette will have the wrong amount.

  5. Transfer 40 uL from the green cap vial to the yellow cap vial. Ensure that all of the solution has been transferred by drawing up and dispensing the yellow cap vial solution three times. Cap both vials and shake or vortex the yellow vial well.

  6. Discard the used pipette tip and attach a new one. Repeat steps 6 and 7 using the yellow cap vial and solution and transfer 40 uL of the yellow vial solution to the blue cap vial. Once again, ensure complete transfer by drawing up and dispensing the blue cap vial solution three times. Cap both vials and shake or vortex the blue vial well.



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