Measurement of a psychoactive compound in kratom supplements

Kratom is a plant native to Southeast Asia that has a variety of effects, many due to the active compound Mitragynine that is present in varying amounts in the plant.  For this reason, you can find kratom in vitamin stores being sold as a supplement.  It is marketed as an energy booster, mood enhancer, pain reliever, and antidote for opioid withdrawal, but there are many concerns about the safety of its use.  The goal here is not to inform on or debate the use of kratom, but rather to demonstrate a method for the analysis of the main active ingredient, Mitragynine, in kratom supplements.

In this study we analyze 4 different samples of kratom in the Lucidity LC-UV and use a Mitragynine standard to develop a calibration curve which can be used to quantitate the amount of Mitragynine in the 3 kratom samples.

We started with a 1 mg/mL standard of Mitragynine from Cayman Chemical, which we used to create 3 standards of 0.010 mg/mL, 0.020 mg/mL, and 0.035 mg/mL in Methanol.

We then ran these samples on the Lucidity LC-UV using the following method, where Solvent A is 90:10% 10mM Ammonium Acetate in H2O:MeOH and Solvent B is 10:90% 10mM Ammonium Acetate in H2O:MeOH.

The standards produced the following cgrams:

0.010 mg/mL Mitragynine standard

0.020 mg/mL Mitragynine standard

0.035 mg/mL Mitragynine standard

Overlay of all 3 standards

These 3 samples produced a nice calibration curve with an R squared of 0.9988.

We then prepared the kratom samples, all of which were in capsule form by putting them in the SimplePrep using Methanol as the solvent.  The SimplePrep added Methanol, agitated, and heated the samples, leaving the capsules fully dissolved in Methanol.  We then diluted the samples in Methanol to get the concentrations (based on label claims) into the range of our calibration curve. We then ran 4 samples using the calibration curve to determine the amount of Mitragynine present in the samples.

Sample A

Sample B

Sample C

Sample D

For each of the 4 samples the software gives us a value for amount of Mitragynine in mg/mL based on the calibration curve.  This concentration can then be converted to mg of Mitrogynine per capsule based on knowing the amount of Methanol the capsule was dissolved and diluted in.  This amount of Mitragynine in mg per capsule is what is show in column 3 in the table below and used to calculate the percent of label claim shown in column 4, which is the amount of Mitragynine measured in a capsule versus the amount of Mitragynine claimed on the label in a capsule of the sample.

Summary of recoveries

The recoveries range from 106.5% to 115.1%, which is a little bit high, but this could be due to a number of different factors, since we don’t know how these samples were tested.